bluuebunny/crossref_metadata_2025_split huggingface dataset:
Involvement of Cholecystokinin in Food Intake: II. Lactational Hyperphagia in the Rat
Authors: Lindén A. , Uvnäs‐Moberg K. , Forsberg G. , Bednar I. , Enerotht P. , Södersten P. 
Published: September 2006

AbstractThe role of Cholecystokinin in the hyperphagia of lactation was studied by measuring the concentration of this hormone in plasma and cerebrospinal fluid in relation to food intake in lactating rats. Cholecystokinin was measured by high‐performance liquid chromatography and radioimmunoassay in plasma and by radioimmunoassay in cerebrospinal fluid. Plasma concentrations of Cholecystokinin were increased in freely‐fed lactating rats compared with non‐lactating, regularly cycling rats. However, after 24 h of food deprivation the concentration of plasma Cholecystokinin was markedly decreased in the lactating rats to levels which were lower than those of non‐lactating animals. Furthermore, plasma levels of Cholecystokinin did not increase in response to 1 h of feeding in lactating rats, whereas in non‐lactating rats they did. In contrast, the concentration of cholecystokinin‐like immunoreactivity in the cerebrospinal fluid was the same in freely‐fed lactating and non‐lactating rats. As in plasma, food deprivation markedly decreased the levels of cholecystokinin‐like immunoreactivity in the cerebrospinal fluid of lactating rats but unlike in plasma, the levels were restored by feeding. The levels of cholecystokinin‐like immunoreactivity were not changed under these conditions in the non‐lactating rats. These results show that there is no correlation between the concentration of Cholecystokinin in plasma and cerebrospinal fluid, which supports the suggestion that the cholecystokinin‐like immunoreactivity in the cerebrospinal fluid is derived from the brain. Removal of the litter from lactating rats deprived of food for 24 h reduced food intake and increased the concentration of cholecystokinin‐like immunoreactivity in the cerebrospinal fluid, but not in plasma. The inhibition of food intake caused by an intraperitoneal injection of Cholecystokinin octapeptide increased after litter removal. It is suggested that hunger in the lactating rat is reflected by a decrease in the levels of cholecystokinin‐like immunoreactivity in the cerebrospinal fluid and satiety by the restoration of these levels.
Characterization of Glucocorticoid Binding Capacity in Human Mononuclear Lymphocytes: Increase by Metyrapone is Prevented by Dexamethasone Pretreatment
Authors: Rupprecht Rainer , Kornhuber Johannes , Wodarz Norbert , Göbel Claudia , Lugauer Johannes , Sinzger Christian , Beckmann Helmut , Riederer Peter , Möller Otto Albrecht 
Published: September 2006

AbstractAutoregulation of receptor systems by their own ligands is a well established biological phenomenon. While down‐regulation of the glucocorticoid binding capacity by glucocorticoids has been shown in animals and humans, data on up‐regulation processes in humans are lacking. To further explore glucocorticoid receptor plasticity in relation to endogenous ligands, glucocorticoid binding parameters were assessed in 15 healthy controls before and after oral administration of 1.5 g metyrapone with and without dexamethasone pretreatment. Administration of metyrapone resulted in blockade of the feedback of the hypothalamic‐pituitary‐adrenal system as shown by the rise in adrenocorticotropin levels, while pretreatment with 1 mg dexamethasone completely suppressed adrenocorticotropin concentrations. Glucocorticoid binding sites per lymphocyte exhibited an increase of 63% following metyrapone administration, which was prevented by dexamethasone pretreatment. Comparison of morning and afternoon glucocorticoid binding sites per cell in 11 healthy volunteers further revealed a diurnal rhythm of glucocorticoid receptor sites. These data suggest that human lymphocyte glucocorticoid receptors are under autoregulatory control.
11Beta‐Hydroxysteroid Dehydrogenase Messenger Ribonucleic Acid Expression, Bioactivity and Immunoreactivity in Rat Cerebellum
Authors: Moisan Marie‐Pierre , Seckl Jonathan R. , Brett Lawrence P. , Monder Carl , Agarwal Anil K. , White Perrin C. , Edwards Christopher R. W. 
Published: September 2006

Abstract11β‐Hydroxysteroid dehydrogenase (11β‐OHSD) metabolizes corticosterone to inactive 11‐dehydrocorticosterone and thus protects non‐specific mineralocorticoid receptors from exposure to corticosterone in the kidney in vivo. Clearly, 11β‐OHSD might also regulate corticosterone access to glucocorticoid receptors. We have investigated cerebellum, a tissue with high glucocorticoid receptor, but very low mineralocorticoid receptor levels and have shown marked 11β‐OHSD bioactivity with similar co‐substrate requirements and inhibition kinetics to the renal enzyme. 11β‐OHSD messenger ribonucleic acid was expressed in cerebellum and was localized in Purkinje and granule cells. This distribution was confirmed immunohistochemically. Thus, we provide evidence for 11β‐OHSD in cerebellum and suggest that it may regulate the access of corticosterone to glucocorticoid receptors in addition to mineralocorticoid receptors.
Vasopressin Release Following Microinjection of Angiotensin II into the Caudal Ventrolateral Medulla Oblongata in the Anaesthetized Rabbit
Authors: Allen A. M. , Mendelsohn F. A. O. , Gierobat Z. J. , Blessing W. W. 
Published: September 2006

AbstractStimulation of the caudal ventrolateral medulla in rats and rabbits elicits secretion of vasopressin from the neurohypophysis. Inhibition of the area attenuates baroreceptor‐initiated vasopressin secretion. Angiotensin II receptor binding sites and angiotensin‐like immunoreactive nerve terminals are localized in the caudal ventrolateral medulla, in the region of the A1 noradrenaline‐synthesizing neurons. To examine the possible functional role of angiotensin II in this region, we have microinjected angiotensin II into the A1 area in the urethane‐anaesthetized rabbit. Microinjection of angiotensin II (0.1 to 100 pmol in 100 nl) stimulated vasopressin secretion (plasma vasopressin concentration increased from 24 ± 8 pg/ml to 104 ± 8 pg/ml following microinjection of 10 pmol angiotensin II) and produced a depressor response with bradycardia. The responsive area was confined to the region of the A1 cell group. AII responses were blocked by prior intramedullary injection of an angiotensin II receptor antagonist, [Sar1, Thr8] angiotensin II (2 nmol in 200 nl), which had no effect on the response to the excitatory amino‐acid N‐methyl‐D‐aspartate. Following spinal blockade of efferent sympathetic activity, microinjections of angiotensin II into the caudal ventrolateral medulla caused a similar increase in plasma vasopressin concentration without a depressor response, demonstrating that the stimulation of vasopressin release by angiotensin II was not secondary to hypotension. Microinjection of [Sar1, Thr8] angiotensin II dramatically attenuated the normal secretion of vasopressin in response to systemic haemorrhage. Following injection of vehicle into the caudal ventrolateral medulla, haemorrhage stimulated an increase in plasma vasopressin concentration from 3 ± 1 pg/ml to 335 ± 75 pg/ ml (n = 5). After microinjection of [Sar1, Thr8] angiotensin II the haemorrhage‐induced change in vasopressin concentration was only 17 ± 6 pg/ml to 35 ± 7 pg/ml (n = 4). Microinjection of the N‐methyl‐D‐aspartate receptor antagonist, DL‐amino‐5‐phosphonovaleric acid (5 nmol, n = 4), did not alter the secretion of vasopressin in response to haemorrhage. These results in the anaesthetized rabbit suggest that angiotensin II in the caudal ventrolateral medulla may have a physiological role in baroreceptor control of vasopressin release.
Corticotrophin‐Releasing Factor‐41 in the Human and Rat—Utility of a Highly Sensitive Enzyme Amplified Immunometric Assay
Authors: Milton N. G. N. , Hillhouse E. W. , Fuller J. Q. , Self C. H. 
Published: September 2006

AbstractWe have developed a highly sensitive and specific immunoassay for human/rat corticotrophin‐releasing factor‐41 (CRF‐41) to enable determination of immunoreactive CRF‐41 levels in biological samples. To achieve high specificity, sensitivity and speed we have used two antisera in a sandwich enzyme immunoassay combined with enzyme amplification. The assay has a sensitivity of 0.08 fmol/well compared with radioimmunoassay sensitivities of 0.5 fmol/tube and is highly specific for the intact CRF‐41 molecule. Measurement of samples is complete within 24 h compared with the 5 days required to obtain sensitive radioimmunoassay measurement. The assay has been used to measure both rat hypothalamic CRF‐41 tissue content and release in vitro with good correlation when compared to radioimmunoassay measurement using antisera rC70 (0.983) or R1 (0.953). The assay only measures immunoreactive CRF‐41 coeluting with human/rat CRF‐41 and its oxidized form Met [O21,38]CRF‐41 in human and rat tissue extracts separated by high‐performance liquid chromatography. The ability to measure immunoreactive CRF‐41 in unextracted plasma allows rapid measurement and eliminates multiple extraction steps.
Effect of Atrial Natriuretic Peptide on the Vasopressin Response to Osmotic and Hemorrhagic Stimuli in Dogs
Authors: Inoue Minoru , Kimura Tokihisa , Ota Kozo , Shoji Masaru , Sato Kazutoshi , Ohta Masahiro , Yamamoto Tadasu , Yoshinaga Kaoru 
Published: September 2006

AbstractEffect of atrial natriuretic peptide (ANP) on the vasopressin response to osmotic stimulation (Experiment I) as well as to hemorrhage (Experiment II) was investigated in anesthetized dogs. Moreover, cardiovascular function and renal water and electrolyte excretion were studied. In Experiment I, 2.5 M NaCI, containing 0.02 μg.kg 1 of ANP, was infused intravenously at a rate of 0.2 ml.kg−1, min 1 after one bolus injection of 0.75 μg.kg 1 ANP (HSA group). In the control group, 2.5 M NaCI alone (HS group) was infused. The infusion was continued for 75 min. In Experiment II, 0.15 M NaCI, containing the identical dose of ANP to Experiment I (HA group), or 0.15 M NaCI alone (H group) was infused intravenously during bleeding at a rate of 1 ml.kg−1.min −1 for 40 min. In Experiment I, infused ANP suppressed the vasopressin response to a mild osmotic stimulation, but not to a strong osmotic stimulation and attenuated ANP release and a rise in arterial and central venous pressures in response to plasma volume expansion, without the enhanced natriuresis. In Experiment II, infused ANP neither impaired the vasopressin response to bleeding nor potentiated a fall in mean arterial pressure and central venous pressure.In conclusion, ANP at physiological and/or supraphysiological range may suppress the vasopressin response to a mild osmotic stimulation, but not to a strong osmotic stimulation and to hemorrhage. In addition, ANP given intravenously may attenuate ANP release and a rise in blood pressure without any natriuresis.
Sex‐Related Differences in Dendritic Branching of Cells in the Prefrontal Cortex of Rats
Authors: Kolb Bryan , Stewart Jane 
Published: September 2006

AbstractMale and female Sprague‐Dawley rats were given either gonadectomies or sham surgery on the day of birth. In adulthood they were sacrificed and prepared for Golgi‐Cox staining. Using a camera lucida technique, layer II/III pyramidal neurons were drawn in the anterior cingulate cortex areas 1 and 3 and the agranular insular cortex and the number of dendritic branches on the apical and basilar dendrites were then summarized. The results showed that the dendritic arbor of prefrontal cortical cells varied as a function of sex and neonatal gonadectomy. In cingulate 3, castrated males had a smaller arbor on the left relative to normal males, whereas, in cingulate 1 the reverse was found. In addition, females had less apical arbor than males in the cingulate areas, whereas, in the agranular insular cortex, females had greater apical arbor than the males. Furthermore, in this region, gonadectomized groups had less arbor than their respective control groups. Finally, in the agranular insular cortex, the dendritic arbor was greater in the left hemisphere.
Noradrenaline, Dopamine and Serotonin Release in the Paraventricular and Supraoptic Nuclei of the Rat in Response to Intravenous Cholecystokinin Injections
Authors: Kendrick K. , Leng G. , Higuchi T. 
Published: September 2006

AbstractMicrodialysis sampling was used to measure noradrenaline, dopamine and serotonin release in the supraoptic and paraventricular nuclei of urethane‐anaesthetized rats following intravenous injection of 20μg/kg cholecystokinin. This dose of cholecystokinin stimulates oxytocin release from the posterior pituitary, while slightly inhibiting vasopressin release. Dialysis probes were placed in the paraventricular nucleus, and into dorsal or ventral regions of the supraoptic nucleus. Samples were collected at 10‐min intervals in each animal before, during and after two injections of cholecystokinin, and following a control injection of 0.9% NaCI. The injections of cholecystokinin stimulated significant increases in the concentrations of noradrenaline, dopamine and serotonin in the paraventricular nucleus and of noradrenaline and serotonin in the dorsal supraoptic nucleus region. Conversely, in the ventral supraoptic nucleus region a significant reduction in noradrenaline release was observed, but dopamine and serotonin concentrations were not significantly affected. The control injections did not alter noradrenaline, dopamine or serotonin release.
Prolactin Implants in the Hypothalamus Inhibit Prolactin Surges During Pregnancy and Alter Prolactin Release in Response to Dopamine Receptor Blockade
Authors: Vidal Gabriela , Mathiasen Joanne R. , Voogt James L. 
Published: September 2006

AbstractThe purpose of this study was to determine whether prolactin (PRL) could exert a negative feedback on it's own secretion during pregnancy and following ovariectomy, and to determine the possible mechanism by which this feedback acts. Implantation of ovine PRL into the arcuate nucleus‐median eminence area of the hypothalamus completely inhibited the nocturnal PRL surge during pregnancy in the rat, and lowered baseline PRL to almost undetectable levels in the ovariectomized rat. When ovariectomized rats implanted with ovine PRL in the hypothalamus were injected with the dopamine receptor blocker domperidone the PRL response was significantly lower than in control rats implanted with albumin. Pregnancy increased the ability of domperidone to cause PRL release following ovine PRL implantation compared to what occurred in ovariectomized rats. These results suggest that PRL implantation increases the secretion of dopamine from the tuberoinfundibular neurons, resulting in a decrease in PRL secretion.
Neurophysins, rather than Receptors, are Involved in [3H]Oxytocin and [3H]Vasopressin Binding Detected by Autoradiography in the Hypothalamo‐Neurohypophyseal System
Authors: Freund‐Mercier M. J. , Stoeckel M. E. , Waeber C. , Kremarik P. , Palacios J. M. , Richard Ph. 
Published: September 2006

AbstractThe goal of the present experiments was to analyse the binding of oxytocin (OT) and vasopressin (VP) in the hypothalamo‐neurohypophyseal system to determine whether [3H]OT and [3H]VP binding in this system involved interaction with receptor sites or with neurophysins. Using quantitative autoradiography, several experiments were performed to compare [3H]OT‐ and [3H]VP‐binding characteristics in this system and in brain areas containing identified receptor sites. Saturation experiments indicated much lower affinity of [3H]OT and [3H]VP binding in the magnocellular nuclei and neural lobe than on brain receptors. Competition experiments using selective ligands indicated interaction with neurophysins rather than with receptors in the hypothalamo‐neurohypophyseal system. This system was never labelled in the presence of a [125I]OT antagonist, a selective OT receptor ligand. In contrast with receptors elsewhere in the brain, the magnocellular nuclei were labelled by [3H]OT and [3H]VP in the absence of MgCI2. In the pituitary neural lobe, density of binding sites was moreover obviously related to the amount of neurosecretory granules, as seen in acutely dehydrated rats. Taken together, these data strongly suggest that in the hypothalamo‐neurohypophyseal system [3H]OT and [3H]VP bind to neurophysins rather than to specific receptors.
Immunohistochemical Localization of Multiple Forms of Gonadotropin‐Releasing Hormone in the Brain of the Adult Frog
Authors: di Meglio M. , Masucci M. , D'Aniello B. , Lela L. , Rastogi R. K. 
Published: September 2006

AbstractImmunohistochemical mapping with antibodies against four different types of gonadotropin‐releasing hormone (GnRH)‐like neuro‐peptides has been studied in the brain of adult Rana esculenta. This study confirms the earlier described distribution pattern of the immunoreactive mammaiian GnRH system in the frog brain, as well as revealing that this system of neuronal cell bodies and fibres is immunopositive to antisera for mammalian, chicken‐I, chicken‐II and salmon GnRH‐like molecules. The results also indicate coexistence of the four GnRH variants in the same anatomical areas. The presence of immunoreactive fibre endings in the cerebellum is also described, perhaps for the first time in the vertebrate brain. In addition, it was found that many immunoreactive GnRH fibres arising in the anterior preoptic area and thalamus‐periventricular area project posteriorly to reach the interpeduncular nucleus‐tegmentum area, thus connecting the diencephalon with the rhombencephalon. These data provide further information on the complex GnRH system in the frog brain. What role(s) in vivo the non‐mammalian forms of GnRH‐like peptides may play in amphibian reproduction is briefly discussed, and in the light of paucity of data it is here stressed that more amphibian species should be studied.
In vivo Intracellular Recording of Neurons in the Supraoptic Nucleus of the Rat Hypothalamus
Authors: Dyball R. E. J. , Tasker J‐G. , Wuarin J‐P. , Dudek F. E. 
Published: September 2006

AbstractIntracellular recordings were made from cells in the hypothalamic supraoptic nucleus in the urethane‐anaesthetized male rat using the ventral surgical approach. Impalements lasted from 5 min to 1 h and recorded cells had an input resistance of 55 to 170 megohms. Spikes of over 50 mV were recorded from 14 cells which could be antidromically activated by stimulation of the neural stalk. The spikes showed a hyperpolarizing afterpotential and the broadening characteristic of rapidly firing magnocellular neurons, which recovered rapidly (<200 ms). When depolarized, the cells showed evidence of a transient potassium current. Recurrent synaptic coupling between the recorded cell and adjacent cells would be expected to alter the hyperpolarizing afterpotential of an antidromic spike as compared with a spontaneous spike; no perceptible difference in the waveforms of the different types of spike could be detected in 11 spontaneously active cells. Application of just subthreshold stimuli to the neural stalk did not evoke depolarizing or hyperpolarizing potentials. Suprathreshold shocks to the neural stalk, when the antidromic spike was prevented by collision, also had no discernible effect on membrane potential. Thus intracellular recordings from magnocellular neurons in vivo revealed electrophysiological properties similar to those seen in vitro. No evidence for synaptic interconnection between magnocellular neurons was found in male rats.
Changes in the Release of Gamma‐Aminobutyric Acid and Catecholamines in the Preoptic/Septal Area Prior to and During the Preovulatory Surge of Luteinizing Hormone in the Ewe
Authors: Robinson Jane E. , Kendrick Keith M. , Lambart Christine E. 
Published: September 2006

AbstractThe technique of intracranial microdialysis was used to monitor changes in the outflow of the catecholamines, noradrenaline, adrenaline and dopamine and the inhibitory amino‐acid γ‐aminobutyric acid (GABA) in the preoptic/septal area of the conscious ewe during an oestradiol‐induced surge of luteinizing hormone (LH). The same animals were sampled twice from an identical brain site, once in the presence of oestradiol and once in its absence, when no surge occurred and LH levels remained low. Changes in the outflow of GABA, noradrenaline and adrenaline (but not dopamine) were related to changes in LH secretion. Specifically, GABA outflow was maximal in the hours following oestradiol administration but began a sustained fall some 10 h before the surge began, to level off just before the first increment in LH secretion. Low GABA concentrations were maintained until after gonadotrophin levels had once more returned to baseline. The release of all three catecholamines was pulsatile. Noradrenergic activity was greater in the presence of oestradiol although activity did not alter over the 20 h of sampling. The pulse frequency of adrenaline was maximal in the hours immediately prior to the LH surge and minimal in the hours following its initiation. These data suggest that a decrease in GABAergic transmission in the vicinity of the LH‐releasing hormone cell bodies is a necessary component of the neural mechanism by which the oestradiol‐induced surge of LH is generated. A general increase in noradrenergic activity coupled with changes in the release of adrenaline at the time of the surge may be additional prerequisites for successful ovulation.
Monoamine Content of the Stalk‐Median Eminence and Hypothalamus in Adult Female Sheep as Affected by Daylength
Authors: Thiery J‐C. 
Published: September 2006

AbstractIn the ewe, plasma luteinizing hormone and prolactin concentrations exhibit seasonal variations. During long days, inhibition of pulsatile luteinizing hormone secretion is mediated by monoamines. In a model of ovariectomized ewes bearing a subcutaneous oestradiol implant, we previously showed that the steroid‐dependent inhibition of luteinizing hormone involves the A15 dopaminergic nucleus of the retrochiasmatic area. In the present work, we compared the aminergic activities of tele‐diencephalic structures in groups of ovariectomized ewes under artificial illumination for short versus long days (8 versus 16 h/day of light, respectively). Half the animals in each group were bearing a subcutaneous oestradiol implant. Using high‐performance liquid chromatography and electrochemical detection, we measured the levels of amines and amine metabolites in ‘punches’ of tissues from regions containing luteinizing hormone‐releasing hormone axon terminals or cell bodies and catecholaminergic structures. Concurrently, we checked the pulsatile luteinizing hormone release and plasma prolactin concentration to assess the ability of our model to mimic seasonal changes in the hormonal status.As expected, ovariectomized ewes with a subcutaneous oestradiol implant showed an inhibition of the pulsatile luteinizing hormone release under long days. A higher concentration of plasma prolactin was also observed under long days, without any effect of the steroid treatment. Under this light regimen, statistically significant higher contents of dopamine than under short days were found in the stalk‐median eminence. Larger contents of homovanillic acid, a dopamine metabolite, and 4‐hydroxy‐3‐methoxyphenylethyleneglycol (MHPG), a noradrenaline metabolite were observed in the infundibular nucleus, while the catechola‐mines themselves remained unchanged. Furthermore, oestradiol also significantly increased the content of MHPG in the latter structure. During long days, animals without oestradiol treatment exhibited a significant lower content of noradrenaline in the A15 nucleus, without any alteration of the dopamine content. Daylength or oestradiol treatment had no significant effects on the levels of amines or amine metabolites in the preoptic or septal areas. Thus, our results in the ewe underline the role played by the medial basal hypothalamus in the catecholaminergic regulation of seasonal changes in hormone release and suggest modifications in the turnover of the neurotransmitters in some structures.