bluuebunny/crossref_metadata_2025 huggingface dataset:
Leptin Receptor Immunoreactivity is Associated with the Golgi Apparatus of Hypothalamic Neurones and Glial Cells
Authors: Diano Sabrina , Kalra Satya P. , Horvath Tamas L.
Published: March 2003

Leptin has emerged as a major peripheral hormone, controlling central mechanisms of metabolism and related autonomic and endocrine functions. In the regulation of hypothalamic neurones, leptin is suggested to affect different second messenger systems and transcription regulating factors. The present study reports the predominant localization of leptin receptor immunoreactivity in the cis and trans cisternae of the Golgi apparatus in hypothalamic neuronal and glial cells. In these hypothalamic cells, translocation of leptin receptor immunoreactivity from the Golgi apparatus to the perikaryal membrane, nucleus or to the cytoplasm was not apparent after manipulation of the metabolic state either by fasting or suppression of the thyroid axis. On the other hand, leptin receptor immunoreactivity was associated with the perikaryal membrane of neurones in other parts of the central nervous system, including the dentate gyrus and the cingulate cortex. These data indicate an extremely high turnover of leptin receptors in hypothalamic target sites, but also raise the possibility that leptin may interact with the Golgi apparatus‐related mechanisms to alter intracellular mechanisms.
Observations on the Orexigenic Hypothalamic Neuropeptide Y‐System in Neonatally Overfed Weanling Rats
Authors: Plagemann  , Harder  , Rake  , Waas  , Melchior  , Ziska  , Rohde  , Dörner
Published: March 2003

Early postnatal overnutrition is a risk factor for obesity in juvenile and adult life. Underlying pathophysiological mechanisms are still unclear. Hypothalamic neuropeptides are decisively involved in the regulation of body weight and food intake. In this study, we investigated consequences of early postnatal overnutrition, as compared to normo‐and undernutrition, on NPY within the arcuate nucleus and paraventricular nucleus (PVN). The normal litter size of Wistar rats was adjusted on the third day of life from 10 pups (normal litters, NL; normonutrition) to only three newborns (small litters, SL; overnutrition) or 18 pups per mother (large litters, LL; undernutrition). SL rats developed clear overweight until the day 21 of life (P<0.0001), as well as hyperleptinaemia (P<0.001), and hyperinsulinaemia (P<0.01). LL rats were underweight and had decreased leptin and insulin concentrations. Using radioimmunoassay, NPY contents were determined in hypothalamic micropunches, and immunocytochemistry for NPY was performed in serial hypothalamic sections on day 21 of life. While in the underweight, hypoleptinaemic, and hypoinsulinaemic LL rats increased concentrations of NPY in the arcuate nucleus and PVN were observed, no decrease in NPY content was found in the overweight, hyperleptinaemic, and hyperinsulinaemic SL rats. Moreover, the percentage of NPY‐immunopositive neurones per total number of neurones was increased not only in the LL rats, but also in the SL rats. Since the NPY system is functionally mature already at this age, these findings might indicate an acquired resistance of the hypothalamic NPY system to increased levels of insulin and/or leptin in early postnatally overfed SL rats.
Photic Regulation of mt1 Melatonin Receptors in the Siberian Hamster Pars Tuberalis and Suprachiasmatic Nuclei: Involvement of the Circadian Clock and Intergeniculate Leaflet
Authors: Schuster  , Gauer  , Guerrero  , Lakhdar‐Ghazal  , Pevet  , Masson‐Pevet
Published: March 2003

In the Siberian hamster suprachiasmatic nuclei and pars tuberalis of the pituitary, high affinity mt1 melatonin receptors are present. We have previously shown that night applied light pulse induced an increase in mt1 mRNA expression in the suprachiasmatic nuclei of this species, independently of the endogenous melatonin. Here, we report the photic regulation of melatonin receptor density and mRNA expression in the suprachiasmatic nuclei and pars tuberalis of pinealectomized Siberian hamsters and the implication in this control of either the circadian clock or the intergeniculate leaflet. The results show that: (1) A 1‐h light pulse, delivered during the night, induces a transitory increase in mt1 mRNA expression in the suprachiasmatic nuclei and pars tuberalis. After 3 h this increase has totally disappeared (suprachiasmatic nuclei) or is greatly reduced (pars tuberalis). (2) The melatonin receptor density, in the suprachiasmatic nuclei, is not affected by 1 or 3 h of light, while it is strongly increased in the pars tuberalis. (3) In hamsters kept in constant darkness, the mt1 mRNA rise is gated to the subjective night in the suprachiasmatic nuclei and pars tuberalis. In contrast, the light‐induced increase in melatonin binding is also observed in the subjective day in the pars tuberalis. (4) intergeniculate leaflet lesion totally inhibits the mt1 mRNA expression rise in the suprachiasmatic nuclei, while it has no effect on the light‐induced increase in mt1 mRNA in the pars tuberalis. However, the light‐induced increase in melatonin receptor density is totally prevented by the intergeniculate leaflet lesion in the pars tuberalis. These results show that: (1) the photic regulations of mt1 mRNA expression and receptor density are independent of each other in both the suprachiasmatic nuclei and pars tuberalis; and (2) the circadian clock and the intergeniculate leaflet are implicated in the photic regulation of melatonin receptors but their level of action differs totally between the suprachiasmatic nuclei and pars tuberalis.
Androgenic Regulation of Steroid Hormone Receptor mRNAs in the Brain of Whiptail Lizards
Authors: Godwin  , Hartman  , Nag  , Crews
Published: March 2003

Sex and species differences in androgenic regulation of steroid hormone receptor mRNAs were examined in the diencephalon of two species of whiptail lizards: Cnemidophorus inornatus is a sexual species and the direct evolutionary ancestor to Cnemidophorus uniparens, an all‐female parthenogenetic species. Lizards were gonadectomized and treated with different doses of either aromatizable testosterone or nonaromatizable dihydrotestosterone. The relative abundances of androgen‐, oestrogen‐, and progesterone‐receptor mRNAs were compared in various nuclei following in situ hybridization with homologous riboprobes. A diversity of patterns in androgenic regulation was observed, with effects differing according to brain region, the steroid‐receptor mRNA being considered and, in some cases, between androgens. In the ancestral sexual species, intact males had lower androgen‐receptor mRNA abundances than castrated, blank‐implanted males in the medial preoptic area. Testosterone significantly decreased androgen‐receptor mRNA abundance in the medial preoptic area of castrated males. Males had higher androgen‐receptor mRNA levels in the preoptic area than females generally and neither the sexual or parthenogenetic females showed a decrease in androgen‐receptor mRNA with androgen treatment. Both testosterone and dihydrotestosterone increased oestrogen‐receptor mRNA abundance in the ventromedial hypothalamus of C. inornatus, but no sex differences in this effect were observed. Gonadectomy decreased, whereas androgen treatment increased, progesterone‐receptor mRNA abundance in the ventromedial hypothalamus. There was a sex difference in this response to androgen in the sexual species, with males having greater amounts than females in this brain area. The parthenogenetic species exhibited a similar pattern to females of the sexual species, but the levels were higher overall, possibly because Cnemidophorus uniparens is triploid. The periventricular preoptic area showed a different pattern, with testosterone treatment increasing progesterone‐receptor mRNA abundance in both sexes of the sexual species and in the parthenogenetic species, while dihydrotestosterone did not. The diversity of patterns in androgen effects indicates that gonadal sex, aromatization of androgen, and perhaps gene dosage all influence the expression of steroid‐receptor mRNAs in the lizard brain.
Neural Circuits Regulating Pulsatile Luteinizing Hormone Release in the Female Guinea‐Pig: Opioid, Adrenergic and Serotonergic Interactions
Authors: Gore A. C. , Terasawa E.
Published: March 2003

We studied three neurotransmitters involved in the regulation of pulsatile luteinizing hormone (LH) release: opioid peptides, serotonin and norepinephrine, using the ovariectomized guinea‐pig. This is an attractive animal model due to the regularity of its LH pulses, enabling any disruptions to be clearly ascertained. In all experiments, a specific agonist or antagonist was administered, either alone or serially to enable detection of interactions, and effects on mean LH concentrations, pulse amplitude and interpulse interval were determined by PULSAR analysis. In the ovariectomized guinea‐pig, catecholamines are stimulatory (acting through the α1 and α2 but not β receptors, unlike other species), opioids inhibitory and serotonin permissively stimulatory to pulsatile LH release. Stimulatory effects of the opiate antagonist were not blocked by pretreatment with an α1‐ or α2‐adrenergic antagonist. Similarly, pretreatment with the opiate antagonist did not prevent the suppression of LH release by α1 and α2 antagonists. This suggests that, in the guinea‐pig, effects of opiates and catecholamines on LH release are exerted by independent pathways to luteinizing hormone releasing hormone (LHRH) neurones. For the opiate–serotonin interactions, pretreatment with the serotonergic antagonist did not block the stimulatory effect of the opiate antagonist on LH release. However, pretreatment with the opiate agonist could not be overcome by the serotonergic agonist. This suggests that the effects of the serotonin system on LHRH release may be indirectly mediated by opioid neurones. Taken together, these studies demonstrate that the three neurotransmitter systems studied are critically involved in normal pulsatile LH release in the female guinea‐pig, and demonstrate novel functional relationships between the opioid and the adrenergic and serotonergic systems.
Increased Synaptic Input to Gonadotropin Releasing Hormone Cells in Preoptic Area Grafts That Support Reproductive Development in Female Hypogonadal Mice
Authors: Rajendren G. , Gibson M. J.
Published: March 2003

Ultrastructural studies have established that gonadotropin releasing hormone (GnRH) neuronal cell bodies receive sparse synaptic input compared to other neuronal cell types. In the present studies, immunocytochemistry for the presynaptic marker synaptophysin, coupled with confocal microscopy, was employed to evaluate whether there was a difference in synaptic input to GnRH cells within preoptic area grafts (hypogonadal, HPG; preoptic area, POA) in hypogonadal female mice that did or did not show ovarian development. GnRH cells in HPG/POA mice with ovarian development exhibited significantly higher numbers of synaptophysin immunoreactive (syn‐IR) appositions as compared with HPG/POA mice without ovarian development. This suggests that synaptic input to the grafted GnRH cells is important for the correction of reproductive functions in HPG/POA mice. Following mating, Fos immunoreactivity was present in several GnRH cells in HPG mice with successful POA grafts, indicating the establishment of neuronal projections conveying somatosensory information to the GnRH cells in these mice. The presence of a higher number of syn‐IR appositions to GnRH cells in the successful grafts supports this hypothesis.
Rapid Upregulation of Aromatase mRNA and Protein Following Neural Injury in the Zebra Finch (Taeniopygia guttata)
Authors: Peterson R. Scott , Saldanha C. J. , Schlinger B. A.
Published: March 2003

The expression of aromatase (oestrogen synthase) within the vertebrate central nervous system (CNS) is key in the provision of local oestrogens to neural circuits. Aromatase expression appears to be exclusively neuronal under normal conditions. However, some in vitro studies suggest the presence of astrocytic aromatase in songbirds and mammals. Recently, aromatase in reactive astrocytes has been demonstrated in response to neural injury in the mammalian CNS. Since the glial aromatase expression first documented in cultures of the songbird telencephalon may reflect processes similar to those in response to mammalian neural injury, we investigated whether injury alters the pattern of aromatase‐expression in the zebra finch, a species with very high levels of forebrain aromatase expression. Adult males received a penetrating neural injury to the right hemisphere and were killed either 24 or 72 h later. Controls were anaesthetized and otherwise unmanipulated. We determined the expression of aromatase mRNA and protein using in situ hybridization and immunocytochemistry, respectively. Both the transcription and translation of aromatase is dramatically upregulated around the lesion site in response to neural injury in the zebra finch forebrain. This effect is robust and rapid, occurring within 24 h of the injury itself. Cells that upregulate aromatase appear to be reactive astrocytes based upon morphology. The hemisphere contralateral to the injury and both hemispheres in control birds showed the normal, exclusively neuronal pattern of aromatase expression. The upregulation of aromatase in astrocytes may provide high levels of oestrogen available to modulate processes such as CNS repair. Injury‐induced upregulation of astrocytic aromatase may be a general characteristic of the injured vertebrate brain.
Calcium‐Dependent Effects of Melatonin Inhibition of Glutamatergic Response in Rat Striatum
Authors: Escames G. , Macías M. , León J. , García J. , Khaldy H. , Martín M. , Vives F. , Acuña‐Castroviejo D.
Published: March 2003

The effects of melatonin, amlodipine, diltiazem (l‐type Ca2+ channel blockers) and ω‐conotoxin (N‐type Ca2+ channel blocker) on the glutamate‐dependent excitatory response of striatal neurones to sensory‐motor cortex stimulation was studied in a total of 111 neurones. Iontophoresis of melatonin produced a significant attenuation of the excitatory response in 85.2% of the neurones with a latency period of 2 min. Iontophoresis of either l‐ or N‐type Ca2+ channel blocker also produced a significant attenuation of the excitatory response in more than 50% of the recorded neurones without significant latency. The simultaneous iontophoresis of melatonin + amlodipine or melatonin + diltiazem did not increase the attenuation produced by melatonin alone. However, the attenuation of the excitatory response was significantly higher after ejecting melatonin + ω‐conotoxin than after ejecting melatonin alone. The melatonin–Ca2+ relationship was further supported by iontophoresis of the Ca2+ ionophore A‐23187, which suppressed the inhibitory effect of either melatonin or Ca2+ antagonists. In addition, in synaptosomes prepared from rat striatum, melatonin produced a decrease in the Ca2+ influx measured by Fura‐2AM fluorescence. Binding experiments with [3H]MK‐801 in membrane preparations from rat striatum showed that melatonin did not compete with the MK‐801 binding sites themselves although, in the presence of Mg2+, melatonin increased the affinity of MK‐801. The results suggest that decreased Ca2+ influx is involved in the inhibitory effects of melatonin on the glutamatergic activity of rat striatum.
The Percentage of Pituitary Gonadotropes with Immunoreactive Oestradiol Receptors Increases in the Follicular Phase of the Ovine Oestrous Cycle
Authors: Tobin V. A. , Pompolo S. , Clarke I. J.
Published: March 2003

During the oestrous cycle, there is an alteration in gonadotrope responsiveness to gonadotropin releasing hormone (GnRH). One cellular mechanism that may be involved in these changes at the pituitary level is the hormonal regulation of oestrogen receptor (ER) expression. Using double‐label immunohistochemistry, we examined the proportion of gonadotropes, lactotropes and somatotropes with immunoreactive (ir) oestrogen receptor alpha (ERα) in pituitary sections from ewes at three stages of the ovine oestrous cycle (n = 8 per group). The percentage of ERα positive cells that also stained positive for luteinizing hormone (LH) increased in the transition from the luteal phase to the follicular phase (n = 8), with no further increase at the time of oestrus (n = 8). In the pituitaries from the luteal phase sheep, only a small number (15%) of lactotropes and 4% of somatotropes were found to contain ir‐ERα and there were no alterations across the oestrous cycle. When we examined pituitaries from ovariectomized (OVX) ewes treated (i.m.) with either oestradiol benzoate (50 µg) or oil vehicle for 2, 4, 6 or 16 h (n = 4 per group), there was no effect of treatment. In fact, the percentage of gonadotropes that were ERα‐positive in OVX ewes was similar to that observed in the pituitaries from the follicular phase ewes, both of which display a high frequency of pulsatile GnRH secretion. We conclude that the number of gonadotropes that contain ir‐ERα increases in the follicular phase of the oestrous cycle and this may enhance the responsiveness of these cells to oestrogen and GnRH. We suggest that this may be due to increased pulsatile GnRH input rather than rising oestrogen levels.
A New Perspective on Glucocorticoid Feedback: Relation to Stress, Carbohydrate Feeding and Feeling Better
Authors: Laugero Kevin D.
Published: March 2003

Input to and regulation of activity in the hypothalamic‐pituitary‐adrenal (HPA) axis is diverse and complex. Glucocorticoid feedback is a major component that determines activity in this classic neuroendocrine axis and, while feedback occurs through the brain, the pathways that mediate glucocorticoid feedback remain unknown. In this review, I discuss findings that have led us to view glucocorticoid feedback in the HPA axis in a new light. Much of what has precipitated this view comes from a very surprising finding in our laboratory; sucrose ingestion normalizes feeding, energy balance and central corticotropin releasing factor expression in adrenalectomized (ADX) rats. Since this discovery, a diverse set of literature that supports this view of glucocorticoid feedback has been found. Taken together, recent findings of the well‐known importance of glucocorticoids to feeding and energy balance, and the modulatory actions of carbohydrate ingestion on both basal and stress‐induced activity in the HPA axis, strongly suggest that many metabolic (e.g. obesity) and psychological (e.g. depression) pathologies, which often present together and have been associated with stress and HPA dysregulation, might, in part, be understood in light of our new view of glucocorticoid feedback.
Increased Galanin Synapses onto Activated Gonadotropin‐Releasing Hormone Neuronal Cell Bodies in Normal Female Mice and in Functional Preoptic Area Grafts in Hypogonadal Mice
Authors: Rajendren G.
Published: March 2003

Galanin synaptic input onto gonadotropin‐releasing hormone (GnRH) neuronal cell bodies was analysed in female mice using the presynaptic vesicle‐specific protein, synaptophysin (Syn) as a marker. In the first experiment, forebrain sections from normal ovariectomized ovarian steroid‐primed mice exhibiting a surge of luteinizing hormone were processed for immunohistochemical labelling for GnRH, synaptophysin, galanin and Fos. Two representative sections from each brain, one passing through the anterior septum (anterior section) and the other through the organum vasculosum lamina terminalis‐preoptic area (posterior section), were analysed under the confocal microscope. None of the GnRH cells analysed in the anterior sections were Fos immunoreactive (IR) or received input from galanin‐IR fibres. In contrast, the majority of GnRH cells in the posterior sections analysed were Fos‐positive. The number of galanin synapses onto the Fos‐positive GnRH cells was significantly higher than that in the Fos‐negative cells in this area of the brain, even though the number of Syn‐IR appositions was comparable to each other. Transplantation of preoptic area (POA) into the third cerebral ventricle of hypogonadal (HPG) mice corrects deficits in the reproductive system. In the second experiment, synaptic input to GnRH cells was compared between HPG/POA mice with (functional graft) or without (nonfunctional graft) gonadal development. The mean numbers of Syn‐IR appositions and galanin synapses per GnRH cell and the proportion of GnRH cells with galanin input were significantly higher in the functional than in the nonfunctional grafts. The results suggest that galanin can act directly on the GnRH cell bodies and may have an important regulatory role on the GnRH system.
Chronic Neuropeptide Y Y5 Receptor Stimulation Suppresses Reproduction in Virgin Female and Lactating Rats
Authors: Toufexis D. J. , Kyriazis D. , Woodside B.
Published: March 2003

Continuous infusion of neuropeptide Y (NPY) disrupts cyclicity and delays the onset of puberty in female rats indicating that NPY can suppress reproduction. Central application of NPY also reliably increases food intake in rats. States with heavy demands on energy resources where reproduction is also inhibited, such as lactation, are similarly accompanied by elevations in central NPY expression. In previous studies, we have shown that, compared to lactating rats fed ad libitum, food‐restricted lactating rats exhibit a longer period of lactational diestrus that is correlated with increased central NPY expression. These studies link NPY to the inhibition of reproduction that is mediated by low availability of energy resources. Here, we examine the effect of chronic 7‐day infusion of the mixed Y1/Y4/Y5 agonist (Leu31, Pro34) NPY and selective agonists to the Y2 (NPY13‐36) and Y5 (D‐Trp32 NPY and D‐Trp34 NPY) receptors on food intake and the oestrous cycle of virgin female rats. We also investigated the effect of chronic infusion from day 8–15 postpartum (pp) of D‐Trp32 NPY and D‐Trp34 NPY on food‐intake and the length of lactational diestrus in lactating rats fed ad libitum. In virgin females, infusion of (Leu31, Pro34) NPY and both the Y5 agonists lengthened the period between consecutive oestrus days while the Y2 agonist NPY13–36 was without effect. Selective Y5 receptor activation alone caused an increase in food intake in virgin females. In lactating females, D‐Trp32 NPY extended the length of lactational diestrus, while D‐Trp34 NPY had no effect on this parameter. These data suggest that Y5 receptor activation suppresses the reproductive axis in both virgin and lactating rats and that Y5 receptor activation enhances food‐intake in virgin females.
Prostaglandin F2α‐Induced Nest‐Building Behaviour is Associated with Increased Hypothalamic c‐fos and c‐jun mRNA Expression
Authors: Walton S. L. , Burne T. H. J. , Gilbert C. L.
Published: March 2003

Intramuscular injection of the naturally occurring prostaglandin F2α (PGF2α) to sexually mature female pigs induces luteolysis and rapidly elicits a behavioural response consistent with pre‐partum nest‐building. Intramuscular injection of the synthetic prostaglandin F2α (cloprostenol) also induces luteolysis but no nest‐building behaviour is observed. The effects of PGF2α, but not cloprostenol, on nest‐building behaviour may be mediated via peripheral PGF2α receptors (FP) or via direct action on central FP receptors. We have previously shown FP receptor mRNA to be localized in porcine paraventricular nucleus (PVN), supraoptic nucleus (SON) and pars dorso‐medialis of the suproptic nucleus (SOD), suprachiasmatic nucleus, choroid plexus and anterior and intermediate pituitary lobes. In this experiment, we examined hypothalamic expression of the immediate early genes c‐fos and c‐jun mRNA after treatment with PGF2α or cloprostenol. Twenty‐one 8‐month‐old nulliparous female pigs (gilts) were injected intramuscularly with a luteolytic dose of PGF2α (15 mg), cloprostenol (175 µg) or saline control, their behaviour was recorded and they were killed 60 min later. Coronal hypothalamic sections and control ovarian tissues were incubated with 45‐mer oligonucleotide probes complementary to porcine c‐fos and c‐jun genes using standard in situ hybridization histochemistry techniques. Significantly higher c‐fos and c‐jun mRNA expression was found in PGF2α‐treated compared to saline or cloprostenol‐treated pigs in the PVN, SON and SOD. Significantly higher c‐fos and c‐jun mRNA expression was found in corpus lutea of PGF2αand cloprostenol‐treated pigs compared to saline controls. Treatment with PGF2α induced nest‐building behaviour whereas treatment with cloprostenol and saline did not. This suggests that PGF2α, or one of its metabolites, and not cloprostenol, crosses the blood–brain barrier and acts directly on hypothalamic receptors to mediate its effect on nest‐building behaviour.
Lipopolysaccharide‐Induced Oestrogen Receptor Regulation in the Paraventricular Hypothalamic Nucleus of Lewis and Fischer Rats
Authors: Tonelli L. , Kramer P. , Webster J. I. , Wray S. , Listwak S. , Sternberg E.
Published: March 2003

Oestrogen receptor (ER) regulation of gene transcription in neurosecretory and pituitary cells has been proposed as an important mechanism for increased hypothalamic‐pituitary‐adrenal (HPA) axis responses in females of several mammalian species, including humans. Inbred female Fischer (F344/N) and Lewis (LEW/N) rats have similar oestrogen levels, although Fischer rats exhibit hyper‐ and Lewis rats hypo‐HPA axis responses. The blunted HPA axis response of Lewis rats has been associated with their blunted hypothalamic corticotropin releasing hormone (CRH) expression. To determine if the female CRH expression deficiency in Lewis rats is associated with defective ER expression and regulation, hypothalamic paraventricular nucleus (PVN) transcript levels of CRH and ER were determined under basal conditions and after immune challenge. Microdissected PVN were obtained from control and lipopolysaccharide (LPS) treated Lewis and Fischer rats and CRH, ERα and β mRNA levels were determined by semiquantitative reverse‐transcriptase‐polymerase chain reaction. In addition, ERα and β protein levels were determined by semiquantitative Western blots. ERα and β mRNA and protein levels in the PVN of control Fischer rats were significantly higher than in control Lewis rats. ERα and β mRNA and protein levels in Fischer rats were reduced by LPS administration at the time of maximal CRH mRNA levels but did not change in Lewis rats, an effect independent of oestrogen levels. These data indicate that defective neuroendocrine HPA axis responses are associated with defective ER expression and regulation in Lewis PVN despite oestrogen concentrations.
Syrian Hamster and Rat Display Developmental Differences in the Regulation of Pineal Arylalkylamine N‐Acetyltransferase
Authors: Garidou M.‐L. , Ribelayga C. , Pevet P. , Simonneaux V.
Published: March 2003

In the Syrian hamster, the role of noradrenaline in the regulation of melatonin synthesis is less clear than in the rat. During pineal ontogenesis in the rat, noradrenaline is the major transmitter involved in the onset of melatonin synthesis and melatonin rhythm. We analysed the involvement of noradrenaline in the ontogenesis of melatonin synthesis in the Syrian hamster and compared it with that of the rat. We followed the developmental profile of melatonin content in parallel with those of mRNA expression and activity of AA‐NAT, the melatonin rhythm‐generating enzyme. In addition, we tested the effect of noradrenergic drugs at early steps of pineal ontogenesis. In the Syrian hamster, the night‐time Aa‐nat mRNA, first detected 3 days after birth, increases progressively up to a maximum reached at 30 days of age and then decreases significantly towards adulthood. The daytime level of Aa‐nat mRNA remains always low. A significant day/night rhythm appears 10 days after birth, is maximal (200‐fold nocturnal increase) 30 days after birth and decreases slowly towards adulthood. Ontogenesis of the AA‐NAT activity rhythm is similar, although with a much lower amplitude of day/night variations (four‐fold). The developmental pattern of melatonin content is similar to that of AA‐NAT and could be correlated with the appearance of sympathetic innervation in the pineal gland. However, neither α‐ nor β‐adrenergic antagonists inhibit the night‐time Aa‐nat mRNA transcription in the 9‐day‐old Syrian hamster, in contrast to what is observed in the adult. For comparison, the β‐adrenergic antagonist propranolol inhibits Aa‐nat gene expression in 2‐day‐old rat. These results show that both species are different in the regulation of the appearance of melatonin synthesis and that Syrian hamster is peculiar from birth in term of noradrenaline involvement in the activation of melatonin synthesis.
Isolation and Structure–Bioactivity Characterization of Glycosylated N‐Pro‐Opiomelanocortin Isoforms
Authors: Lu J. , Swinnen E. , Proost P. , De Vreese B. , Vankelecom H. , Denef C.
Published: March 2003

The N‐terminal fragment of mouse pro‐opiomelanocortin (N‐POMC) was isolated from AtT‐20 cell‐conditioned medium on the basis of immunoreactivity to an anti‐POMC1‐50 monoclonal antibody by a concentration step, a cation exchange step, reversed phase high‐performance liquid chromatography (HPLC) and size exclusion HPLC. Two groups of N‐POMC isoforms with a molecular weight (MW) of approximately 11 kDa and 13 kDa, respectively, were identified by mass spectrometry and N‐terminal amino acid sequencing. C‐terminal sequencing indicated that 11 kDa isoforms correspond to POMC1‐74 and 13 kDa isoforms to POMC1‐95. Isoforms from both groups enhanced the prolactin mRNA content (measured by means of TaqMan real‐time reverse transcription‐polymerase chain reaction) in cultured rat pituitary cell aggregates in a dose‐dependent manner, but not all of them showed this activity. POMC1‐74 compounds were significantly more potent than POMC1‐95 isoforms. The observed effects were abolished by coincubation with the monoclonal anti‐POMC1‐50 antibody, showing the specificity of this biological action. Incorporation of bromodeoxyuridine into DNA of immunostained lactotrophs was enhanced by only a minor part of the isoforms. Some of these had no effect on prolactin mRNA expression. The N‐POMC isoforms appeared to be N‐ and at least in part O‐glycosylated. After enzymatic N‐deglycosylation of selected N‐POMC isoforms, the stimulatory effect on the prolactin mRNA level was depressed (in case of the POMC1‐95 isoforms) or totally abolished (in case of the POMC1‐74 isoforms). The present findings show that N‐POMC is a mixture of differentially glycosylated isoforms, that the isoforms of POMC1‐74 are the biologically more effective forms and that different isoforms induce different biological responses in the same cell population. The data also show the essential role of N‐glycosylation in the biological response.
Orexin‐A Immunoreactivity and Prepro‐Orexin mRNA Expression in Hyperphagic Rats Induced By Hypothalamic Lesions and Lactation
Authors: Sun G. , Narita K. , Murata T. , Honda K. , Higuchi T.
Published: March 2003

Orexins are endogenous neuropeptides that potently facilitate appetite and food consumption. In the present study, we examined orexin immunoreactivity and prepro‐orexin mRNA expression in the lateral hypothalamus by immunohistochemistry and competitive reverse transcription‐polymerase chain reaction (RT‐PCR) methods in different models of hyperphagia in rats. Hyperphagia was induced by lesions of either the ventromedial hypothalamus (VMHL) or the paraventricular nucleus (PVNL), and we also compared lactating rats to nonlactating controls. Both VMHL and PVNL increased food intake and body weight compared to shams. On day 7 post lesion, serum leptin and insulin concentrations exhibited 3.2‐ and 2.8‐fold increases in VMHL rats, and nonsignificant 1.8‐ and 1.8‐fold increases in PVNL rats; there were significant decreases (48% and 33%) in lactating rats on day 12 postpartum compared to controls, respectively. Serum glucose concentrations were not significantly changed compared to controls in these rats. Quantification by image analysis suggests that VMHL significantly decreased the number and mean staining intensity of orexin‐A immunoreactive neurones compared to those in the sham‐lesioned group; while PVNL did not change orexin‐A immunoreactivity. Competitive RT‐PCR analysis showed that VMHL significantly decreased the prepro‐orexin mRNA expression compared to those in the sham‐lesioned group, and PVNL did not change it. Lactating rats on days 11–12 of lactation had significantly greater number and mean staining intensity of orexin‐A immunoreactive neurones, prepro‐orexin mRNA expression food intake and body weight than nonlactating postpartum rats. Thus, changes in orexin‐A immunoreactivity and prepro‐orexin mRNA expression were not consistent between the hyperphagia models. These results suggest that the hyperphagia from VMHL or PVNL and lactating rats differ in their involvement of orexin‐A, and the change in circulating leptin and insulin concentrations may be involved in the change of orexin‐A immunoreactivity in these rats.
Serotonin Receptors Involved in Vasopressin and Oxytocin Secretion
Authors: Jørgensen H. , Riis M. , Knigge U. , Kjær A. , Warberg J.
Published: March 2003

Serotonin (5‐HT), 5‐HT agonists, the 5‐HT precursor 5‐hydroxytryptophan, 5‐HT‐releasers and ‐reuptake inhibitors stimulate the release of vasopressin and oxytocin. We investigated the involvement of 5‐HT receptors in the serotonergic regulation of vasopressin and oxytocin secretion. Vasopressin and oxytocin secretion was stimulated by 5‐HT, the 5‐HT1A+1B+5A+7 agonist 5‐carboxamidotryptamine (5‐CT), the 5‐HT2A+2C agonist DOI, the 5‐HT2C+2A agonist mCPP, the 5‐HT2C agonist MK‐212, the 5‐HT3 agonist SR 57277 and the 5‐HT4 agonist RS 67506. The 5‐HT1A agonist 8‐OH‐DPAT, which had no effect on vasopressin secretion, stimulated oxytocin secretion. The 5‐HT‐induced release of vasopressin and oxytocin was inhibited by central infusion of the 5‐HT antagonists WAY 100635 (5‐HT1A), LY 53857 (5‐HT2A+2C), ICS 205‐930 (5‐HT3+4) and RS 23597 (5‐HT4). The 5‐HT2+6+7 antagonist metergoline in combination with the 5‐HT1A+2+7 antagonist methysergide inhibited the stimulatory effect of 5‐CT on both hormones, whereas the 5‐HT1A+1B antagonist cyanopindolol only inhibited the oxytocin response. The 5‐HT2A antagonist 4‐(4‐flourobenzoyl)‐1‐(4‐phenylbutyl)‐piperidine oxalate had no effect on DOI‐induced hormone response. The 5‐HT2C antagonist Y 25130 partly inhibited the stimulating effect of MK‐212. ICS 205‐930 and RS 23597 inhibited vasopressin and oxytocin secretion induced by RS 67506. WAY 100635 inhibited 8‐OH‐DPAT‐induced oxytocin secretion. We conclude that 5‐HT‐induced vasopressin secretion primarily is mediated via 5‐HT2C, 5‐HT4 and 5‐HT7 receptors, whereas 5‐HT2A, 5‐HT3 and 5‐HT5A receptors seem to be of minor importance. 5‐HT‐induced oxytocin secretion involves 5‐HT1A, 5‐HT2C and 5‐HT4 receptors; in addition an involvement of 5‐HT1B, 5‐HT5A and 5‐HT7 receptors seems likely, whereas 5‐HT2A and 5‐HT3 receptors seem to be less important.
In Vitro Effects of Catecholamines and Catecholestrogens on Brain Tyrosine Hydroxylase Activity and Kinetics in the Female Catfish Heteropneustes fossilis
Authors: Chaube R. , Joy K. P.
Published: March 2003

Effects of catecholamines and catecholestrogens on tyrosine hydroxylase (TH) activity and kinetics were investigated in the telencephalon and hypothalamus of female Heteropneustes fossilis in gonad quiescent (resting) and recrudescent (preparatory) phases. Dopamine, noradrenaline and adrenaline and the catecholestrogen, 2‐hydroxyestradiol‐17β inhibited TH activity in a concentration‐dependent manner in both resting and preparatory phases, with a higher effect in the resting phase. Two‐ methoxyestradiol‐17β did not alter TH activity in any season. The catecholamines inhibited TH in a competitive manner increasing apparent Km values significantly without altering the apparent Vmax. Two‐hydroxyestradiol‐17β inhibited significantly the enzyme in a noncompetitive manner and decreased apparent Vmax without altering apparent Km values. The apparent Ki is higher for dopamine than noradrenaline or adrenaline. The apparent Ki for 2‐hydroxyestradiol‐17β is not significantly different from that of noradrenaline. The present results suggest an interaction between oestradiol‐17β (E2) and catecholamine metabolism at the level of tyrosine hydroxylation and E2 effects on catecholamines may be mediated through its 2‐hydroxylation.
The influence of some demographic and clinical variables on psychosomatic traits of patients requesting replacement removable partial dentures
Authors: Wakabayashi N. , Yatabe M. , Ai M. , Sato M. , Nakamura K.
Published: March 2003

SUMMARY The purpose of this study was to investigate the influence of some demographic and clinical variables on psychosomatic traits of the patients who visited the prosthodontic section of the Dental Hospital at Tokyo Medical and Dental University for replacement of their removable partial dentures (RPDs). Sixty‐six patients with 50 maxillary and 44 mandibular RPDs completed the psychological measurements concerning their dentures using visual analogue scales (VAS). Female patients rated significantly lower satisfaction with the comfort of their dentures than males. Younger patients expressed less satisfaction with the aesthetics of their dentures than the older patients. The period of wearing the present denture significantly correlated with psychological measures of pain, comfort, and general satisfaction, suggesting that this clinical variable may be an important factor. There was no significant correlation between the patients’ general satisfaction with dentures and the retention/stability scores assessed by the examiner.
Amalgam alternatives – microleakage evaluation of clinical procedures. Part II: direct/indirect composite inlay systems
Authors: Ziskind D. , Elbaz B. , Hirschfeld Z. , Rosen L.
Published: March 2003

SUMMARY This study investigated the degree of dye penetration of two composite inlay systems with different adhesive and bonding protocol. Forty whole extracted premolars and molars were collected. The teeth were immediately stored in water at room temperature. Class II cavity preparations were prepared and restored both, in the direct and the indirect techniques (Coltene Brilliant®) and (Kulzer Estilux posterior CVS®). The inlays were cemented with a composite luting cement (ART®‐Bond) and (Kulzer, Adhesive cement®). Specimens were subjected to 750 cycles of thermal stress. They were than immersed in 2% Basic fuchsin dye. The teeth were sectioned in three planes before being ranked as to the amount of dye penetration. The data were analysed by the Wilcoxon's rank test at the 95% confidence level. There was no statistically significant difference between the direct and indirect technique considered separately for each composite inlay material, at the cervical margin location. The fuchsin staining in the occlusal area was limited to the enamel in all groups. By using the composite inlay, the factor of adaptation and bonding of composites to dentine become the significant factor contributing to leakage.
The effect of parafunction on condylar asymmetry in patients with temporomandibular disorders
Authors: Miller V. J. , Yoeli Z. , Barnea E. , Zeltser C.
Published: March 2003

This study was undertaken to examine the relationship between condylar asymmetry and parafunction in patients with temporomandibular disorders (TMD). Twenty‐eight patients with TMD and parafunction and 30 patients with TMD but no parafunction were examined. A panoramic radiograph was obtained for each patient and from this the condylar asymmetry determined. The group with parafunction showed a significantly (P < 0·005) higher asymmetry index than did the group with no noticeable parafunction. Patients were grouped into the following age ranges: 10–19 years, 20–29 years, 30–39 years, and 40 + years. The mean asymmetry index was determined for each age range for both groups of patients. The group of patients with TMD and parafunction had a higher mean asymmetry index in all the age ranges studied. This suggests that muscle hyperactivity may be a factor in the increased asymmetry found in patients with TMD.
The effect of diabetes mellitus on histopathological changes in the denture‐supporting tissues under continuous mechanical pressure in rat
Authors: Mori S. , Sato T. , Hara T. , Shirai H. , Maruo Y. , Minagi S.
Published: March 2003

The histopathological changes in denture‐supporting tissues of streptozotocin‐induced diabetes mellitus rat were studied in relation to continuous mechanical pressure exerted through an experimental denture base. The experimental dentures were designed to load continuous mechanical pressures (3·4, 1·5 or 0·5 kPa) to the hard palate of the molar region of a rat. From the results of this study, the following conclusions were drawn: the streptozotocin‐induced diabetic condition (1) tended to prolong the appearance period of a shortened epithelial ridge, and weakened the phenomenon, (2) reduced the appearance period and severity of the compression of epithelium, (3) delayed the time of manifestation of the proliferative change in the recovery process of the shortened epithelial ridge, and weakened the phenomenon, (4) prolonged the appearance period of the compressed lamina propria mucosae, and enhanced the phenomenon, (5) reduced the number of osteoclasts, (6) lowered the threshold for induction of the osteoclastic bone resorption to between 1·5 and 0·5 kPa, (7) inhibited the appearance of osteoblast which follows the disappearance of osteoclasts, (8) did not induce any inflammatory change, and (9) tended to enhance the longitudinal change of the continuous mechanical pressure. The histopathological changes in the denture‐supporting tissues of the streptozotocin‐induced diabetes mellitus rat related highly to the longitudinal change of the continuous mechanical pressure exerted through the denture base. From the results of this study, it was suggested that the streptozotocin‐induced diabetic condition lowers the tolerance of the denture‐supporting tissues to continuous mechanical pressure.
Unpolymerized surface layer of autopolymerizing polymethyl methacrylate resin
Authors: Vallittu P. K.
Published: March 2003

The aim of this study was to determine the thickness of the unpolymerized surface layer of autopolymerizing polymethyl methacrylate (PMMA) resin. Powder : liquid (P/L) ratios of 10 : 4–10 by weight of the PMMA were tested, and the PMMA resin was polymerized at 55 °C either in water or in air under an air pressure of 100 kPa or 300 kPa. Five samples were polymerized for each of the test groups. The thickness of the unpolymerized surface layer, i.e. inhibition depth of PMMA, was measured by a light microscopic technique with polarized light. The inhibition depth of the samples polymerized in air under 100 kPa pressure varied from 39 to 174 μm, and the samples polymerized under 300 kPa pressure had an inhibition depth of 91–391 μm. The P/L ratio and the polymerization pressure had a significant effect on the inhibition depth (P < 0·001). No inhibition layer was observed in the samples polymerized in water. The results suggest that in order to obtain an adequate degree of polymerization on the surface of autopolymerizing PMMA resin, the polymerization process should be carried out in water.
Association between loss of occlusal support and symptoms of functional disturbances of the masticatory system
Authors: Ciancaglini R. , Gherlone E. F. , Radaelli G.
Published: March 2003

The purpose of this study was to evaluate the association of loss of occlusal support with symptoms of functional disturbances of the masticatory system, in particular with the ones related to the temporomandibular dysfunction. A total of 483 adult subjects randomly selected from the population living in the municipality of Segrate, northern Italy, were studied. Subjects were interviewed by questionnaire about oral conditions and occurrence of symptoms of disturbances of the masticatory system. Also, denture was examined by dentists during the interview. Loss of occlusal support was observed in 60·2% of the subjects, symptoms of functional disturbances in 68·7% and temporomandibular dysfunction in 55·1%. At univariate analysis loss of occlusal support was mainly associated with a feeling of stiffness or fatigue of the jaws (P<0·001), difficulty in closing the mouth (P<0·005) and difficulty on mastication (P<0·0001). Association with temporomandibular dysfunction as a whole was significant also (P<0·001). Multiple age‐ and sex‐adjusted logistic analysis disclosed a significant strong impact of loss of occlusal support on difficulty with mastication (odds ratio=7·0, P<0·0001). At that analysis, no significant relationship resulted with symptoms of temporomandibular dysfunction. These findings confirm that presence of an adequate occlusal support is a relevant factor in maintaining an efficient chewing, and also suggest that it may play any indirect role in preventing occurrence of symptoms of temporomandibular dysfunction.
Quantitative analysis of masseter and temporalis EMGs: a comparison of anterior guided versus balanced occlusal concepts in patients wearing complete dentures
Authors: Grubwieser G. , Flatz A. , Grunert I. , Kofler M. , Ulmer H. , Gausch K. , Kulmer S.
Published: March 2003

The lack of easily measurable, objective physiological activity parameters of the masseter and temporalis muscle during jaw movements in humans has led to the consideration to revise data of surface electromyographies (EMGs) by applying a computerized quantification method. The aim of this follow‐up analysis was to get quantitative data out of EMG‐records of an earlier study. These records were obtained with two different splints, splint 1 providing an anterior front‐canine guidance and splint 2 providing bilateral balanced occlusion. Utilizing a computer aided integration method led to numeric results which statistically proves the prediction of the previous investigation. Applying the integration method, the EMG raw signal was transformed into area‐values which enabled a statistical work up of the data. Wilcoxon test statistics shows a significant (P<0·05) lower muscle activity in patients wearing dentures providing anterior front‐canine guidance compared to those with balanced occlusion. It is concluded that the neuromuscular activity of the elevator muscles is highly reproducible and that the neuromuscular function is similar in edentulous subjects to that found in people with natural teeth. Furthermore, the study statistically proves earlier visual data that all those subjects, whose muscle activities were observed with anterior guidance (splint 1) compared to bilateral balanced occlusion (splint 2) showed significantly lower values with regard to subjects wearing splint 2.
Adjustment of dental occlusion in treatment of chronic cervicobrachial pain and headache
Authors: Karppinen K. , Eklund S. , Suoninen E. , Eskelin M. , Kirveskari P.
Published: March 2003

The hypothesis that the response to conventional physical therapy of patients suffering from chronic cervicobrachial pain and/or headache can be improved by adjusting dental occlusion, was tested. Forty patients seeking treatment were interviewed and examined prior to treatment, and 6 weeks, 12 months and 60 months after treatment. All patients underwent routine physical therapies. They were pairwise matched for age, gender and type of dental occlusion, and randomly allocated to a true occlusal adjustment group or to a mock adjustment group. The patients and the examiners were unaware of the type of dental treatment given. The outcome variables included subjective pain and discomfort, cervical spine mobility and pain on movement, and comparison of relative EMG activities. The short‐term response to therapy was good in both groups. In the long‐term, however, the response was significantly better in the patients who had undergone occlusal adjustment than in the mock‐adjusted controls.