bluuebunny/crossref_metadata_2025 huggingface dataset:
The Noradrenergic Innervation of Identified Hypothalamic Magnocellular Somata and its Contribution to Lactation‐Induced Synaptic Plasticity
Authors: Michaloudi Helen C. , El Majdoubi Mohammed , Poulain Dominique A. , Papadopoulos Georgios C. , Theodosis Dionysia T.
Published: November 2003

Despite several studies showing that the rat supraoptic (SON) and paraventricular (PVN) nuclei are innervated by noradrenergic afferents, the respective contribution of these inputs to the oxytocinergic and vasopressinergic neuronal populations remains to be clearly defined. In the present study, we used the unbiased disector method to estimate the numerical density of noradrenergic varicosities on identified oxytocinergic and vasopressinergic somata in the rat SON and PVN. The analysis was carried out on semithin (1 μm) plastic sections cut from vibratome slices (50 μm) of the SON and PVN which had been double‐labelled for noradrenaline (NA) and oxytocin‐ or vasopressin‐related neurophysin. These preparations displayed many noradrenergic varicosities which electron microscopy showed to represent, in the main, synaptic boutons. Our quantitative analysis revealed that noradrenergic varicosities contacted oxytocinergic and vasopressinergic somata to a similar extent in male and female rats, under basal conditions of hormone secretion. The incidence of these axo‐somatic contacts was similar in the SON and PVN. In contrast, in lactating rats, in which oxytocin secretion is enhanced, there was a significant increase in the density of noradrenergic varicosities apposed to oxytocinergic somata, in both nuclei. Our observations indicate that, in male and female rats under normal conditions, noradrenergic afferents innervate each type of neurosecretory somata, in both magnocellular nuclei, in a similar fashion. They reveal, moreover, that noradrenergic afferents participate in lactation‐induced structural plasticity of synapses impinging on oxytocinergic somata.
Neuroendocrine and Behavioral Responses and Brain Pattern of c‐fos Induction Associated with Audiogenic Stress
Authors: Serge Campeau  , Watson Stanley J.
Published: November 2003

The present study determined simultaneously the behavioural, neuroendocrine and regional brain activity, using semi‐quantitative analysis of c‐fos mRNA induction, produced by 30 min of auditory stimulation at different white noise intensities (background 60 dB, 70, 80, 90 and 105 dBA), in rats. Only the highest noise intensities (90 and 105 dB) significantly increased corticosterone release after 30 min stimulation. Behaviourally, the 105 dB noise condition reliably reduced overall activity, and moderate noise intensities (70 and 80 dB) increased sleeping time. Three distinct patterns of c‐fos mRNA induction were observed. First, following exposure to the experimental cages, a wide pattern of brain activation was obtained in experimental animals irrespective of noise intensity presentation, compared to the naive rats. Second, a number of auditory structures (cochlear nuclei, superior olivary complex, nuclei of the lateral lemniscus, inferior colliculus and the medial division of the medial geniculate body) displayed a clear intensity‐dependent increase in c‐fos induction. Third, compared to all other conditions, the stressed rats (90 and 105 dB conditions) displayed significantly higher c‐fos induction in relatively few areas. Particularly intense c‐fos induction was observed in the bed nucleus of the stria terminalis, especially its anterior medial and ventral aspects, the septohypothalamic nucleus, the ventral lateral septum, the ventral portion of the dentate gyrus, a number of hypothalamic nuclei including the lateral preoptic area, the medial preoptic nucleus and the paraventricular nucleus, the median raphe and the pedunculopontine tegmental nucleus. The involvement of a number of these structures in a specific audiogenic stress responsive circuit is discussed.
Distribution of Fos Immunoreactivity in the Lamina Terminalis and Hypothalamus Induced by Centrally Administered Relaxin in Conscious Rats
Authors: McKinley M. J. , Burns P. , Colvill L. M. , Oldfield B. J. , Wade J. D. , Weisinger R. S. , Tregear G. W.
Published: November 2003

The effect of intracerebroventricular (ICV) injections of synthetic human or rat relaxin (25 or 250 ng) on the distribution of Fos detected immunohistochemically in the rat forebrain was investigated. Following ICV relaxin, many Fos‐positive neurons were observed in the periphery of the subfornical organ, dorsal part of the organum vasculosum of the lamina terminalis, throughout the median preoptic nucleus, supraoptic nucleus and hypothalamic paraventricular nucleus. Such effects did not occur following ICV injection of artificial cerebrospinal fluid or the separated A and B chains of relaxin, nor following the intravenous injection of 250 ng of relaxin. Both vasopressin and oxytocin containing neurons identified immunohistochemically in the supraoptic and paraventricular nuclei exhibited Fos following ICV relaxin, and many neurons in the medial parvocellular part of the paraventricular nucleus contained Fos. The results indicate that centrally administered relaxin may increase neuronal activity in regions of the hypothalamus and lamina terminalis which are associated with cardiovascular and body fluid regulation and oxytocin secretion.
Sex and Reproductive Status Related Brain Content of Mammalian and Chicken‐II GnRHs in Rana esculenta
Authors: Rastogi R. K. , King J. A. , Di Fiore M. M. , D’Aniello B. , Pinelli C.
Published: November 2003

Mammalian and chicken‐II forms of gonadotropin‐releasing hormone (mGnRH and cGnRH‐II, respectively) have been measured simultaneously in the brain, pituitary, and peripheral terminal nerves (nasal area tissue) of adult males and females of a representative amphibian, Rana esculenta, during the annual reproductive cycle. Whereas in the male, brain concentrations of both GnRH forms showed significant reproductive status‐related fluctuations, in the female brain only cGnRH‐II content showed significant changes. The highest GnRH levels were recorded just prior to breeding in both sexes. In the pituitary both GnRHs were present in all seasons. In the peripheral terminal nerves, instead, only mGnRH was detected in all seasons confirming our previous immunohistochemical data. In both sexes furthermore, the brain and pituitary mGnRH levels were consistently much higher than those of cGnRH‐II and there were no sex‐related differences in the brain and pituitary content of GnRHs. Seasonal changes in brain GnRH levels may correlate with plasma sex steroid levels reinforcing the postulate that sex steroids affect GnRH neuronal systems.
Facilitation or Inhibition of the Estradiol‐Induced Gonadotropin Surge in the Immature Rat by Progesterone: Regulation of GnRH and LH Messenger RNAs and Activation of GnRH Neurons
Authors: Attardi Barbara , Klatt Brian , Hoffman Gloria E. , Smith M. Susan
Published: November 2003

We have developed and extensively characterized immature female rat models to demonstrate inhibition or facilitation of the estradiol (E2)‐induced gonadotropin surge by progesterone (P). We show here that the surge of free α‐subunit is regulated similarly by P in these models. To investigate the possibility that P alters the biosynthesis of GnRH and/or LH, we measured levels of LH subunit mRNAs by Northern blot hybridization and GnRH mRNA by a solution hybridization‐RNase protection assay. In the P inhibition model, α‐subunit mRNA was significantly decreased when P was administered together with E2 for 32 or 48 h, and LHβ, at 29 h. In the facilitation model, neither α‐subunit nor LHβ mRNA increased with premature and enhanced release of LH and free α‐subunit. Levels of GnRH mRNA in E2‐treated rats were significantly higher on the afternoon of the LH surge than on that or the following morning. There was no effect of P on GnRH mRNA levels, however, before, during, or after the LH surge in either paradigm. The time course of activation of GnRH neurons in P‐facilitated rats was determined by double‐label immunocytochemistry for GnRH and cFos. When serum LH concentrations were basal there was no expression of cFos in GnRH neurons. LH secretion in P‐facilitated rats was initiated at ≈14.00 h and remained elevated until at least 19.00 h. During this time 63–78% of GnRH neurons were cFos positive. Both serum LH concentrations and the percentage of cFos‐activated GnRH neurons were significantly lower in control rats treated with E2 alone than in those treated also with P. In conclusion: 1) suppression of LH and free α‐subunit secretion by P can be accounted for at least partly by suppression of α‐subunit mRNA levels; 2) P facilitation is not associated with changes in LH subunit or GnRH mRNA levels; 3) the large proportion of cFos‐positive GnRH neurons in P‐facilitated rats closely parallels increases in serum LH concentrations but is not accompanied by changes in GnRH mRNA levels. It is likely, therefore, that P acts in the facilitation model to trigger release of pre‐existing GnRH stores by altering synthesis or activity of neuro‐transmitters/neuropeptides involved in GnRH regulation and/or release of LH stores by altering, for example, pituitary responsiveness to GnRH (including self‐priming) and components of the LH secretory apparatus. Similar possibilities may also obtain for the blockade of the gonadotropin surge in the inhibition model.
Growth Hormone‐Releasing Hormone (GHRH)‐GH‐Somatic Growth and Luteinizing Hormone (LH)RH‐LH‐Ovarian Axes in Adult Female Transgenic Mice Expressing Human GH Gene
Authors: Sasaki F. , Tojo H. , Iwama Y. , Miki N. , Maeda K. , Ono M. , Kiso Y. , Okada T. , Matsumoto Y. , Tachi C.
Published: November 2003

We have examined alterations in the hypothalamo‐pituitary GH‐somatic growth axis and the hypothalamo‐pituitary LH‐ovarian axis in a line of transgenic ICR mice expressing human GH (hGH) under the influence of the whey acid protein promoter. Transgenic female mice weighed twice as much as control females and were infertile. The size of the anterior pituitary (AP) was that of the controls. In transgenic mice, acinar cells in the mammary and mandibular glands displayed hGH‐immunoreactivity, and plasma hGH was detected by radioimmunoassay. In the medial basal hypothalamus (MBH) of transgenic females, the immunoreactive‐GHRH level was decreased (P<0.01). There was a corresponding reduction in the number of GHRH‐immunoreactive neurons in the arcuate nucleus (ARC) and in the immunostaining of GHRH nerve terminals in the median eminence. The level of somatostatin (SRIH) in the MBH was increased (P<0.05), and SRIH‐immunoreactive neurons in the periventricular nucleus (PeV) were increased in size and number in transgenic mice. The MBH level of LHRH in transgenic animals was greater (P<0.01) than in controls, although there was no apparent difference in the number of LHRH‐immunoreactive neurons or in LHRH level in the preoptic area. There are fewer SRIH‐ and LHRH‐immunoreactive neurons in the ARC in transgenic mice. Cells in the AP for GH, PRL, and LH were fewer in transgenic mice. The ovary suffered disturbance of follicular development and of corpora lutea formation.
The Origins and Significance of Pulsatility in Hormone Secretion from the Pituitary
Authors: Gareth Leng  , Brown David
Published: November 2003

In this review we first consider what information is carried by the activity of oxytocin cells. For these, as for many neuroendocrine neurones, synchronized bursting activity leading to pulsatile secretion is particularly important, and we consider possible mechanisms by which bursting may arise, and the role of intrinsic cell properties. Vasopressin cells also show a type of bursting behaviour, but their activity is not synchronized. We show how the behaviour of vasopressin cells fits a very simple dynamical systems model. Even structurally simple dynamical systems models can be computationally complex, with a rich repertoire of behaviour, and we show how the vasopressin cell model can be adapted and expanded to model the LHRH pulse generator network, and how the pituitary responsiveness to hypothalamic releasing factors may also be modelled with a different class of dynamical systems model.
Progesterone Receptor Participates in the Stimulatory Effect of LHRH, Prostaglandin E2, and Cyclic Amp on Lordosis and Proceptive Behaviours in Rats
Authors: Beyer Carlos , González‐Flores Oscar , González‐Mariscal Gabriela
Published: November 2003

We explored the effect of the antiprogestin RU486 on the estrous behaviour (lordosis and proceptivity) induced in sexually experienced ovariectomized oestrogen primed rats by: 5 μg luteinizing hormone‐releasing hormone (LHRH), 100 μg prostaglandin E2 (PGE2), or 2 mg dibutyryl cyclic AMP (db cAMP). Pretreatment with 5 mg RU 486 (but not with vehicle) 60 min before the injection of the above‐mentioned agents significantly decreased both lordosis and proceptive behaviours normally induced by such agents. Results suggest that the estrus‐inducing action of LHRH, PGE2 and db cAMP occurs through the activation of the progesterone receptor.
Cortisol Differentially Regulates Pituitary‐Adrenal Function in the Sheep Fetus after Disconnection of the Hypothalamus and Pituitary
Authors: Ross J. T. , Phillips I. D. , Owens J. A. , McMillen I. C.
Published: November 2003

We have investigated the effects of a 5 day infusion of cortisol into fetal sheep, in which the hypothalamus and pituitary were surgically disconnected (HPD), on fetal pituitary‐adrenal function. Fetal HPD and vascular catheterization were carried out at between 104 and 124 days gestation. Cortisol was administered (3.5 mg 24 h−1) for 120 h between 134 and 140 days (HPD+F group; n=5) and saline was administered during the same gestational age range to HPD (HPD group; n=12) and intact fetal sheep (Intact group; n=6). Cortisol infusion into the HPD fetal sheep did not suppress the mRNA levels for Proopiomelanocortin (POMC) in the fetal anterior pituitary at 139/140 days gestation (POMC mRNA: 18S rRNA: Intact 0.40±0.05; HPD 0.56±0.07; HPD+F 0.49±0.07). Similarly, there was no significant effect of either HPD or cortisol infusion on the plasma concentrations of immunoreactive (ir) ACTH or ACTH(1–39). The adrenal: fetal body weight ratio was significantly higher, however, in the HPD+F (88.4±8.7 mg kg−1) and Intact groups (84.1±5.6 mg kg−1) when compared with the HPD fetal sheep (63.7±5.4 mg kg−1). The ratio of total IGF‐II mRNA: 18S rRNA was similar in the adrenals of the Intact (0.48±0.09), HPD (0.78±0.09) and HPD+F (0.71±0.11) groups. The ratios of CYPIIA1, 3&bgr;‐HSD and CYP21A1 mRNA: 18S rRNA were significantly lower in adrenals from the HPD group when compared to those in the Intact group and were not restored to normal by cortisol infusion.
Primary Cell Culture of LHRH Neurones from Embryonic Olfactory Placode in the Sheep (Ovis aries)
Authors: Duittoz Martine Batailler Anne H. , Caldani Martine
Published: November 2003

The aim of this study was to establish an in vitro model of ovine luteinizing hormone‐releasing hormone (LHRH) neurones. Olfactory placodes from 26 day‐old sheep embryos (E26) were used for explant culture. Cultures were maintained successfully up to 35 days, but were usually used at 17 days for immunocytochemistry. LHRH and neuronal markers such as neurofilament (NF) were detected by immunocytochemistry within and/or outside the explant. Three main types of LHRH positive cells are described: (1) neuroblastic LHRH and NF immunoreactive cells with round cell body and very short neurites found mainly within the explant, (2) migrating LHRH bipolar neurones with an fusiform cell body, found outside the explant, (3) network LHRH neuron, bipolar or multipolar with long neurites connecting other LHRH neurons. Cell morphology was very similar to that which has been described in the adult sheep brain.
Distinct Agonist‐Mediated Endocytosis of Cloned Rat Somatostatin Receptor Subtypes Expressed in Insulinoma Cells
Authors: Roosterman Dirk , Roth Adelheid , Kreienkamp Hans‐Jürgen , Dietmar Richter  , Meyerhof Wolfgang
Published: November 2003

Endocytosis of somatostatin receptors could regulate cellular responses to the two natural peptides, somatostatin‐14 and somatostatin‐28, and to synthetic ligands used in the clinical diagnosis and symptomatic therapy of neuroendocrine tumours. The five cloned SSTRs with or without epitope tags at their carboxyl‐termini were expressed in rat insulinoma 1046‐38 cells. Application of the two natural peptides or octreotide, at 37 °C but not at 4 °C, to cells transfected with somatostatin receptor subtype 2 or 3 cDNA resulted in a significant decrease of cell surface binding‐sites for 125I‐Tyr11‐somatostatin‐14. In contrast, cells transfected with subtype 5 cDNA only responded to stimulation with octreotide or somatostatin‐28. Cells transfected with subtype 1 cDNA responded to somatostatin‐14 and 28, while cells expressing subtype 4 cDNA showed no response. Confocal microscopy revealed that 6 min after stimulation with somatostatin‐14 at 37 °C, tagged somatostatin receptor subtypes 1, 2 and 3 were internalized into vesicles. Internalization was not observed at 4 °C in the presence of 0.4 M sucrose and 80 &mgr;M phenylarsine oxide and hence proceeded via endocytosis through clathrin‐coated pits and vesicles. After 20 min the internalized receptors appeared in perinuclear vesicles and after 120 min they reappeared at the plasma membrane. This recycling was not sensitive to cycloheximide and, hence, not dependent on de novo protein synthesis. Recovery of cell surface receptors was, however, inhibited by brefeldin A, monensin and bafilomycin A1, indicating that receptor recycling proceeded through vesicular traffic of acidified compartments. The data are consistent with the assumption that the observed agonist and subtype specific internalization of somatostatin receptors in a neuroendocrine cell line may be important for tumour diagnosis and therapy and, thus, suggest a manifold control in cellular signalling.
Effect of Corticosterone and Adrenalectomy on NMDA‐Induced Cholinergic Cell Death in Rat Magnocellular Nucleus Basalis
Authors: Ábrahám I. , Veenema A. H. , Nyakas C. , Harkany T. , Bohus B. G. J. , Luiten P. G. M.
Published: November 2003

The present study demonstrates the effects of adrenalectomy and subcutaneously administered corticosterone on N‐methyl‐d‐aspartate‐induced neurodegeneration in the cholinergic magnocellular basal nucleus of the rat. NMDA was unilaterally injected into the nucleus basalis at different plasma corticosterone concentrations in adrenalectomized rats, in adrenalectomized animals with subcutaneously implanted cholesterol‐corticosterone pellets containing 25% or 100% corticosterone, and in sham‐adrenalectomized controls. The neurotoxic impact of the NMDA injection in the various experimental groups was assessed by the loss of cholinergic fibers stained with acetylcholinesterase histochemistry in the parietal neocortex. Reactive cortical astrocytes as a result of the treatments were detected by glial fibrillary acidic protein immunohistochemistry. Measurements of the densities of astrocytes and cholinergic fibers at the injected side of the brain were carried out by image analysis.
Mesotocin Gene Expression in the Diencephalon of Domestic Fowl: Cloning and Sequencing of the MT cDNA and Distribution of MT Gene Expressing Neurons in the Chicken Hypothalamus
Authors: Barth S. W. , Bathgate R. A. D. , Mess A. , Parry L. J. , Ivell R. , Grossmann R.
Published: November 2003

This study focuses on the structure and expression of the mesotocin (MT) gene in the chicken hypothalamus. Using an anchored and nested RT‐PCR strategy, combined with circular RACE‐PCR, the full length sequence of the chicken MT cDNA was obtained. The cDNA and derived amino acid sequences conformed to the structure of the oxytocin‐like gene family. However, unlike most mammalian species, there does not appear to be frequent gene conversion between the MT and AVT cDNA sequences. A single specific hybridization signal of 1.2 kb was detected by Southern analysis of chicken genomic DNA, indicating only a single gene copy in the chicken genome. Northern analysis of hypothalamic RNA revealed a single band at approximately 0.6 kb. Using the same probe for in situ hybridization histochemistry, MT‐mRNA was demonstrated to be predominantly localized in the parvocellular, magnocellular and periventricular subgroups of the paraventricular nucleus and, when compared to the distribution of neurons containing arginine‐vasotocin (AVT)‐mRNA in the same region, with far fewer neurons expressing the MT gene in the lateral subgroups. Only few and scattered neurons expressing the MT gene were found in the ventral and external subgroups of the supraoptic nucleus in which many neurons contain AVT transcripts, as demonstrated in consecutive sections. In all nuclei investigated, the intensity of AVT and MT hybridization signals per cell was approximately equal. No specific labelling for MT‐mRNA was found in the bed nucleus of the stria terminalis, nor the nucleus accumbens. Using immunocytochemical detection of AVT and in situ hybridization for neurons expressing MT‐mRNA, some neurons were found to contain both AVT and MT gene products in the paraventricular nucleus but not in the supraoptic nucleus.
Metabolic and Orexigenic Effects of Intracerebroventricular Neuropeptide Y are Attenuated by Food Deprivation
Authors: Radha Parikh  , Marks Jonathan L.
Published: November 2003

Administration of neuropeptide Y (NPY) into the hypothalamus or cerebral ventricles has been shown to increase food intake, the secretion of hormones such as insulin, glucagon and corticosterone and to alter the metabolism of carbohydrate and lipids. It has been suggested that metabolic effects of hypothalamic NPY may contribute to fat accretion in some types of obesity and to the metabolic and behavioural adaptation to food deprivation. However, it is currently unknown if different nutritional states alter the responses to hypothalamic NPY. Consequently, we have compared the effects of NPY injected into the third ventricle (ICV) in the fed and overnight‐fasted state on ingestive behaviour, on insulin, glucagon and corticosterone secretion before, and following, an IV glucose bolus (IVGTT) and on blood glucose following an intra‐arterial insulin bolus (ITT). Studies were performed on conscious, unrestrained adult female rats. In the fed state, 2 and 6 &mgr;g ICV NPY produced a potent orexigenic and dypsogenic effect. In the fasted state, the 2 &mgr;g dose had a dypsogenic effect, while only the 6 &mgr;g dose had a significant orexigenic effect. In the fed but not fasted state, 3 &mgr;g ICV NPY increased plasma glucagon and corticosterone levels and attenuated the decline in blood glucose during the ITT. By contrast, in both fed and fasted groups, 3 &mgr;g ICV NPY potentiated the insulin secretory response during the IVGTT.
Immunohistochemical Localization of Novel CART Peptides in Rat Hypothalamus, Pituitary and Adrenal Gland
Authors: Koylu Ersin O. , Couceyro Pastor R. , Lambert Philip D. , Ling Nicholas C. , DeSouza Errol B. , Kuhar Michael J.
Published: November 2003

CART peptide specific polyclonal antisera were raised in rabbits. The antisera were raised to CART peptide fragments that span most of the predicted CART protein. The specificity of each antisera was demonstrated by blockade of immunostaining by the immunizing peptide but not by the other CART peptide fragments. In the hypothalamus and pituitary of colchicine and noncolchicine treated rats, immunostaining was observed in cell bodies, fibers and varicosities. Clusters of cells were also stained in the adrenal medulla. It is noteworthy that cellular immunostaining was only found in areas previously shown to express CART mRNA. These findings indicate the presence of CART peptide(s) in the hypothalamus, pituitary, and adrenal gland. Furthermore, we also present evidence for the possible processing of the CART pro‐peptide into smaller peptide fragments. These neuroanatomical findings suggest a role of CART peptides in hypothalamic, pituitary and adrenal function.
Hypoglycaemia‐Induced Inhibition of Pulsatile Luteinizing Hormone Secretion in Female Rats: Role of Oestradiol, EndogenousOpioids and the Adrenal Medulla
Authors: Cagampang Felino Ramon A. , Cates Philippa S. , Sandhu Satwinder , Strutton Paul H. , McGarvey Cliona , Coen Clive W. , O’Byrne Kevin T.
Published: November 2003

Oestradiol (E2) has been shown to exacerbate the inhibitory effect of hypoglycaemic stress on gonadotrophin‐releasing hormone pulse generator (GnRH) activity in primates. The mechanism by which this is mediated is not yet known. We therefore aimed to establish whether there is a sensitizing influence of E2 on the suppression of LH pulsatility in response to hypoglycaemia in the female rat, thus providing a more amenable model in which to study this phenomenon. In ovariectomized Wistar rats with E2 replacement, insulin‐induced hypoglycaemia (0.5 U/kg iv) resulted in an interruption of pulsatile LH secretion. Induction of the same degree of hypoglycaemia in ovariectomized rats without E2 replacement was without effect on LH pulsatility. Naloxone administration prevented the hypoglycaemia‐induced inhibition of LH pulses. Because hypoglycaemia is a potent activator of the sympathetic nervous system, we also tested the hypothesis that the adrenal medulla is involved in this suppression of LH pulses in the rat. Adrenomedullectomy completely prevented this inhibitory response to hypoglycaemic stress. These data are consistent with the hypothesis that E2 sensitizes the GnRH pulse generator to the inhibitory influences of hypoglycaemic stress in the rat. Furthermore, a clear role for both endogenous opioid peptides and the adrenal medulla in the stress‐induced suppression of LH pulsatility is identified.
Effects of Paced Mating on c‐fos Gene Expression in the Female Rat Brain
Authors: Erskine Mary S. , Hanrahan Sinead B.
Published: November 2003

When estrous female rats control or pace (P) their sexual contacts with males, several neuroendocrine and behavioral responses to mating occur that are not observed or are greatly attenuated after nonpaced mating. The present study examined whether the distribution and amount of FOS immunoreactivity (FOS‐IR) induced in brain by mating would be altered in females receiving paced rather than nonpaced mating stimulation. In the first experiment, females received 5 or 15 intromissions during paced mating tests (5P and 15P), 5 or 15 intromissions during nonpaced mating tests (5NP and 15NP), 15 mounts‐without‐intromission (MO) or remained in their homecages (HC). Selective increases 1 h after paced mating stimulation were observed in the posterodorsal medial amygdala (MePD), where significantly more FOS‐IR cells were present in the 5P and 15P groups than in the respective NP groups. The 5P, 5NP and 15NP had significantly more FOS‐IR than the HC, MO, and 5NP groups, and the 5P group had levels of FOS‐IR which were equivalent to that seen in the 15NP group. In the posteromedial portion of the bed nucleus of the stria terminalis (BNSTpm) and the ventrolateral portion of the ventromedial nucleus of the hypothalamus (VMHvl), paced mating induced significantly greater numbers of FOS‐IR cells than did either MO or HC treatments; increases induced by nonpaced mating were not statistically greater than HC controls. No differences between groups were seen in the medial preoptic area (mPOA). In the second experiment, experimentally lengthening the interintromission interval (III) as well as increasing the intromission duration to mimic the characteristics of paced mating, resulted in significant increases in FOS‐IR in the MePD but not in the other three brain regions. These results demonstrate that paced mating is more effective in inducing c‐fos expression than nonpaced mating, and that the MePD is particularly sensitive to differing characteristics of the mating stimuli received.
Pituitary Adenylate Cyclase‐Activating Peptide and Vasoactive Intestinal Peptide Receptor Expression in Immortalized LHRH Neurons
Authors: Olcese J. , McArdle C. A. , Middendorff R. , Greenland K.
Published: November 2003

The regulation of LHRH secretion is extraordinarily multifarious. To no small extent, this insight has been gained through studies using the immortalized hypothalamic LHRH neuronal line, GT1‐7. In the present study, we examined these cells for potential expression of the receptors for the related peptides PACAP and VIP. By means of reverse transcription‐polymerase chain reaction (RT‐PCR) with PACAP receptor‐specific primers, in combination with restriction enzyme analysis and cDNA sequencing, we were able to identify all PACAP‐specific receptor splice variant forms with variable degrees of expression. Of the two nonselective VIP/PACAP receptors (i.e. VIP‐R type I and II) only the latter isoform was detected by RT‐PCR. In view of these results, we sought to establish whether PACAP and VIP receptors are functional in GT1‐7 cells. Cyclic AMP (cAMP) accumulation after addition of PACAP‐38 (or PACAP‐27) was dose‐dependent with maximal 3‐fold increases. VIP also elevated cAMP with a similar potency. Phosphatidylinositol (PI) turnover was unaffected by either PACAP or VIP. Acute LHRH secretion was stimulated equally by nanomolar concentrations of both PACAP and VIP. These results point to PACAP and VIP having direct actions via the VIP2R on cAMP signalling and LHRH release, in addition to the known effects of these peptides on pituitary functions.
Atrial Natriuretic Peptide, Cyclic GMP Analogues and Modulation of Guanylyl Cyclase do not Alter Stimulated POMC Peptide Release From Perifused Rat or Sheep Corticotrophs
Authors: Bowman Maria E. , Robinson Phillip J. , Smith Roger
Published: November 2003

Corticotrophin‐releasing hormone (CRH) and arginine vasopressin (AVP) are two potent stimulators for secretion of proopiomelanocortin (POMC)‐derived hormones, from corticotrophs. CRH also stimulates POMC synthesis. Atrial natriuretic peptide (ANP) has been reported to inhibit POMC peptide release and is thought to act through cGMP signalling pathways. A multicolumn cell perifusion system was used to investigate the role of cGMP signalling pathways in CRH‐ and AVP‐stimulated POMC peptide release from primary cultures of ovine or rat anterior pituitary cells. The CRH and/or AVP stimulations were applied at 30 min intervals as 5 min pulses, and the various treatments were infused over a period of 50 min, overlapping with 2 of the stimulations. ANP (10 nM) had no effect on β‐endorphin (βEP) release from ovine cells, stimulated by 0.5 nM CRH and 5 nM AVP together, or 5 nM CRH and 50 nM AVP separately. Rat anterior pituitary cells were stimulated with 0.05 nM CRH/0.5 nM AVP or 0.5 nM CRH/5 nM AVP and treated with 1 nM or 10 nM ANP, respectively. No inhibition of ACTH or βEP was observed. Similarly, the nitric oxide donors molsidomine (100 μM), SIN‐1 (100 μM) and NaNO2 (100 μM) did not inhibit βEP release stimulated by 0.5 nM CRH/5 nM AVP in ovine cells. The cGMP analogues 8‐bromo‐cGMP (10 μM and 100 μM) and dibutyryl cGMP (100 μM) also had no effect on βEP and ACTH release from ovine or rat anterior pituitary cells. Dexamethasone (8 μM), a synthetic glucocorticoid known to block POMC synthesis and secretion of βEP and ACTH by a distinct mechanism, was used as a control and suppressed CRH/AVP‐stimulated βEP secretion from ovine anterior pituitary cells. These results contrast with some previous studies and demonstrate that the cGMP signalling pathway in sheep or rat anterior pituitary cells does not directly inhibit secretion of POMC‐derived hormones from corticotrophs.
Ontogeny of Glucocorticoid Receptors in the Hyperstriatum‐Hippocampus‐Parahippocampal Area and Optic Tectumof the Embryonic Chicken (Gallus domesticus) Brain
Authors: Bordone L. , Schrott L. M. , Sparber S. B.
Published: November 2003

The importance of glucocorticoids and their perturbation during development is an active research area. Developmental insults, including direct and indirect consequences of exposure to drugs of abuse or withdrawal from them, may act upon or via the neuroendocrine axis of the pregnant experimental subject (e.g. rat) and/or directly upon the neuroendocrine axis of the embryo or fetus. The use of the domestic chicken embryo may constitute a good experimental subject for studying these effects in the absence of maternal influences. Thus, the pattern of brain glucocorticoid cytosolic receptors were characterized in an early developing brain region, the optic tectum (OT) and a later developing region with a different function, the hyperstriatum‐hippocampus‐parahippocampal (HHP) area, on embryonic days (E) 11, 15, 18 and on the day of hatching (HD). The influence of the glucocorticoid synthesis inhibitor metyrapone, injected into eggs on E14 and on E17, upon glucocorticoid receptors (on E15 and E18) was also studied to determine effects of a ‘chemical adrenalectomy’. Receptors for this steroid are high on E11 and E15, decreasing as they approach the time of hatching, with the HHP generally showing greater numbers of specific binding sites for []> 3H]‐corticosterone (CORT). Although metyrapone treatment did not alter the apparent number of receptors on E15, on E18 it unmasked receptors otherwise occupied by endogenous ligand(s) and/or induced their synthesis, resulting in significantly more receptors identified with [3H]‐CORT. Nevertheless, the HHP continued to display more of these receptors than the OT on E15 and E18 after injection of metyrapone. These observations are consistent with the hypotheses that the HHP of embryos of this species contains a higher density of glucocorticoid receptors than does the OT; that glucocorticoid receptor quantification is related to steroid synthesis inhibition in late embryonic development; and that neuroendocrine feedback control of serum glucocorticoids may become functional between E15 and E18. The results also suggest the use of this experimental approach for assessing the effects of developmental insults with drugs, other than metyrapone, as a marker for altered neuroendocrine development and/or function.
Seasonal Variation Of Melatonin Binding Sites In The Pars Tuberalis of the Male Mink (Mustela vison)
Authors: Messager S. , Caillol M. , George D. , Martinet L.
Published: November 2003

The seasonal changes of 2‐[]> 125I]iodomelatonin binding were studied using quantitative autoradiography in the pars tuberalis (PT) of the mink, a short‐day breeder, kept out of doors. Studies were performed at 7 times of the year (July, September, October, January, February, and May), corresponding to different states of responsiveness of the gonadal system to the photoperiod. Melatonin binding was observed in the PT and on the ventral border of the pars distalis. Histological staining revealed that the binding on the border of the pars distalis corresponded to the zona tuberalis, a ventral extension of the PT. The binding was specific and saturable. The density of melatonin binding varied significantly with the time of year. The lowest density of binding was found in July, when animals experienced a long daylength and sexual rest, increased from July to reach a maximum in October, when animals experienced decreasing daylength and the hypothalamo‐pituitary activity resumed, then slightly decreased and remained constant from November to May. The saturation study demonstrated that the decrease in melatonin binding density between October and February resulted from a change in the number (Bmax: October 70.6±4.0 vs February 49.6±2.8 fmol/mg protein; P<0.01) but not in the affinity (Kd: October 33.6±7.1 vs February 20.8±5.1 pM; P>0.05) of the binding sites. These results are discussed according to the different phases of mink reproductive cycle and to reported data on the sites of action of melatonin on seasonal reproduction and prolactin secretion.
Brain Metabolism of Progesterone, Coping Behaviour and Emotional Reactivity in Male Rats from Two Psychogenetically Selected Lines
Authors: Steimer Th. , Driscoll P. , Schulz P. E.
Published: November 2003

Brain metabolites of progesterone such as tetrahydroprogesterone (THP) act on GABAA receptors and have anxiolytic properties. The formation of THP and its 5α‐reduced precursor, dihydroprogestrone (DHP) was measured in vitro in various microdissected brain areas obtained from males of two psychogenetically selected rat lines, i.e. the Roman High‐(RHA/Verh) and Low‐(RLA/Verh) Avoidance rats, which are known to differ in emotional reactivity and/or anxiety. The behavioural and neuroendocrine responses of these rats were also measured following exposure to a novel environment in two different test situations. The formation of DHP and THP was found to be significantly higher in the frontal cortex (FCX), and DHP in the bed nucleus of the stria terminalis (BST), of the hypoemotional RHA/Verh rats. In addition, enzymatic activity in the FCX was found to be inversely correlated with behavioural measures of anxiety. These results suggest that individual, possibly genetically‐determined differences in brain production of endogenous anxiolytics derived from progesterone may account at least in part for the behavioural differences characterizing these two lines, and provide further evidence that neurosteroids acting on the GABAergic system may play an important role in modulating physiological and/or behavioural responses to environmental stressors.
Reduced Aggressive Behaviour in Mice with Targeted Disruption of the Oxytocin Gene
Authors: DeVries A. Courtney , Young III W. Scott , Nelson Randy J.
Published: November 2003

Oxytocin (OT) has been reported to mediate aggressive and affiliative behaviours in several species. The behavioural role of OT has been established with physiological manipulations that potentially affected blood pressure, which may have indirectly affected the behaviours under study. To provide converging evidence of the physiological role of OT in aggressive behavior, wild type (WT), heterozygous (OT−/+), and homozygous (OT−/−) mutant mice were tested in two aggression paradigms. In general, there was no significant difference in aggressiveness between WT and OT−/+ mice. However, there were significant reductions in the duration of aggressive behaviors among OT−/− animals, especially in agonistic encounters within neutral arenas. The OT−/− mice did not exhibit any sensorimotor deficits or display any altered general anxiety levels that may have accounted for the observed reduction in aggressive behavior. These data indicate that aggression is mediated in part by OT in mice and that increased aggressiveness is not an obligatory phenotypic result of targeted genetic disruption of any gene.
Projection Sites of Medial Preoptic Area and Ventral Bed Nucleus of the Stria Terminalis Neurons that Express Fos during Maternal Behavior in Female Rats
Authors: Numan Michael , Numan Marilyn J.
Published: November 2003

Medial preoptic area (MPOA) and ventral bed nucleus of the stria terminalis (VBST) neurons are involved in maternal behavior, but the neural sites to which the maternally relevant neurons project have not been determined. Since MPOA and VBST neurons express Fos during maternal behavior, we used a double‐labeling immunocytochemical procedure to detect both Fos and a retrograde tracer, wheat germ agglutinin (WGA), in order to determine where these Fos neurons project. On Day 4 postpartum, fully maternal females were separated from their litters. On Day 5, WGA was iontophoretically injected into one of the following regions known to receive MPOA and/or VBST input: Lateral septum, medial hypothalamus at the level of the ventromedial nucleus, lateral habenula, ventral tegmental area, retrorubral field, or periaqueductal gray. On Day 7, females received a 2‐h test with either pups or candy, after which they were perfused and their brains were processed for the detection of Fos and WGA. As expected, females tested with pups had more Fos‐containing neurons in the MPOA and VBST than did females tested with candy. After WGA injections into several brain sites, the number of double‐labeled cells observed in the MPOA and VBST was greater for the maternal females when compared to the non‐maternal females. Therefore, these results pinpointed neural circuits that were activated during maternal behavior. For the maternal females, Fos‐containing neurons in the MPOA projected most strongly to the medial hypothalamus at the level of the ventromedial nucleus and to the lateral septum, while Fos‐containing neurons in the VBST projected most strongly to the retrorubral field, ventral tegmental area, and medial hypothalamus. Although relatively few MPOA and VBST neurons which expressed Fos during maternal behavior projected to the periaqueductal gray, these Fos‐expressing neurons made up a relatively large proportion of the MPOA and VBST projection to the periaqueductal gray. This study suggests that MPOA and VBST efferents project to a variety of regions to promote full maternal responsiveness.
Effects of Photoperiod Duration and Melatonin Signal Characteristics on the Reproductive System of MaleSyrian Hamsters
Authors: Powers J. Bradley , Jetton Amy E. , Mangels Robert A. , Bittman Eric L.
Published: November 2003

Three experiments tested effects of photoperiod and the pineal hormone melatonin (MEL) on reproductive function among male Syrian hamsters. In Experiment 1, hamsters were exposed for 32 weeks to 1 of 4 short photoperiods which varied in duration (11.5 L; 10 L; 8 L; 6 L). A fifth group was shifted from 11.5 L to 6 L after 6 weeks. Shorter photoperiods were associated with more rapid regression of the testes, but all groups eventually regressed to the same extent. In contrast, the temporal profile of testicular recrudescence, expressed as males became photorefractory, was not significantly different between groups. A decrease in photoperiod from 11.5 L to 6 L after 6 weeks did not delay the onset of recrudescence. The 11.5 L group was subdivided at week 32 and transferred to either 13 L or 16 L for the next 8 weeks to break photorefractoriness. Upon subsequent exposure to 8 L, both subgroups regressed their testes in similar fashion over weeks 40–52, indicating that the two long photoperiods were equally effective in breaking photorefractoriness. Nevertheless, FSH and prolactin were more consistently suppressed in the 16 L group following the switch to 8 L.
A method of studying adaptive changes of the oropharynx to variation in mandibular position in patients with obstructive sleep apnoea
Authors: L’ESTRANGE P.R. , BATTAGEL J.M. , HARKNESS B. , SPRATLEY M.H. , NOLAN P.J. , JORGENSEN G.I.
Published: November 2003

The aim of this study was to develop a method of studying the effects of mandibular advancement on oropharyngeal airway dimensions in the sagittal plane in conscious, supine patients. Six white, dentate, male patients with proven obstructive sleep apnoea had sagittal fluoroscopic recordings taken in the resting supine position. Images were recorded at four frames per second as the mandible was advanced with the teeth in contact to maximum protrusion and then opened. Software in the fluoroscopic imaging system permitted measurement of the change in mandibular position together with oropharyngeal airway dimensions expressed as the narrowest dimension observable in the post‐palatal and post‐lingual sites. Plotting of airway dimensions during mandibular advancement enabled estimation of the degree of protrusion associated with maximal airway benefits. Progressive mandibular advancement produced variable adaptive changes in the post‐palatal and post‐lingual regions of the oropharynx. The amount of airway opening appeared to be related to the horizontal and vertical relationships of the face and to the dimensions of the soft palate. The changes in post‐palatal and post‐lingual airway dimensions were not always identical, despite the observation that both tongue and soft palate were seen to move in unison, with close contact being maintained between the two structures. Jaw opening resulted in synchronous posterior movement of both tongue and soft palate, with consequent narrowing of oropharyngeal airspace. Fluoroscopy is a simple method of assessing upper airway changes with mandibular advancement in the conscious patient. The technique should facilitate the selection of subjects for whom mandibular advancement would seem advantageous. The nature of the adaptive response is dependent on individual structural variation. It is suggested that, where artificial mandibular advancement with dental devices is considered beneficial, jaw opening should be kept to a minimum.
Mediotrusive tooth guidance and temporomandibular joint sounds in non‐patients and patients
Authors: CHRISTENSEN L.V. , DONEGAN S.J. , McKAY D.C.
Published: November 2003

In 46 non‐patients and 46 patients, the authors examined the presence (+) and the absence (‐) of laterotrusive (LG) and mediotrusive (MG) tooth guidance, i.e. dynamic dental articulation events in contrast to static dental occlusion events. During a right and left laterotrusion/mediotrusion of the mandible, the number of compound, mutually exclusive and exhaustive tooth guidance events (possibilities) was six. In addition, the presence and the absence of temporomandibular joint (TMJ) sounds, provoked TMJ pains, and the associations between TMJ sounds and tooth guidance events were examined. In non‐patients, LG+ and MG+ was relatively infrequent (30%) while LG+ and MG‐ was relatively frequent (70%). In patients, LG+ and MG+ was relatively frequent (58%) while LG+ and MG‐ was relatively infrequent (42%). LG‐ and MG+ was absent in non‐patients and rare in patients (3%). Either unilateral or bilateral MG+ was relatively infrequent in non‐patients (30%) and relatively frequent in patients (59%). Bilateral MG+ was relatively infrequent in non‐patients (20%) and relatively frequent in patients (52%). Either unilateral or bilateral TMJ sounds were relatively infrequent in non‐patients (39%) and relatively frequent in patients (74%). Either unilateral or bilateral provoked TMJ pains were absent in non‐patients and relatively frequent in patients (72%). The authors found no evidence that TMJ sounds were associated with the ipsilateral absence of so‐called balancing contacts (MG‐) in non‐patients and patients. Finally, no evidence supporting the use of a so‐called positive predictive value, an ‘extension concept’ of probability theory was found.
Stomatognathic dysfunctional symptoms in Saudi Arabian adolescents
Authors: ABDEL‐HAKIM A.M. , ALSALEM A. , KHAN N.
Published: November 2003

Secondary school Saudi students participated in a questionnaire about stomatognathic dysfunction symptoms. The adolescents were interviewed about general health, peripheral joint disease, chewing function, oral parafunctions, and symptoms of dysfunction. Thirty‐two per cent of participants had at least one dysfunction symptom. Pain on opening was the most common (35·7%), followed by headache (33·6%), and joint sounds (32·2%). Symptoms increased with decline in general health, particularly the health of peripheral joints. Chewing functions were not impaired. Tooth loss did not affect dysfunction symptoms in adolescents, whilst a weak relation was evident between oral parafunctions and symptoms of mandibular dysfunction.
Histological changes in edentulous oral mucosa under implant‐supported overdentures
Authors: PRETI G. , BASSI F. , BARBERO P. , LORENZETTI M. , VALENTE G.
Published: November 2003

The microscopic characteristics of the mucosa covering the alveolar ridge that supports a complete denture have long been studied. In this paper, any histological changes in mucosa loaded by a denture before and after a denture has been anchored by implant onto the bone were followed. The results suggest that mechanical loads improve trophism of mucosa, and that fixing a denture to implants leads to a more uniform distribution of loads.
Photoelastic stress analysis of mandibular posterior cantilevered pontic
Authors: WANG C.H. , TSAI C.C. , CHEN T.Y.‐F. , CHANG G.L.
Published: November 2003

The quasi‐3D technique of photoelastic stress analysis was used to evaluate the stresses of mandibular posterior cantilevers for distal terminal abutments at various levels of periodontal support. The stress concentration index was selected to compare each model. The periodontal support of terminal abutment and the length of pontic must be considered, when a cantilever fixed partial denture is anticipated.