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B Kerdelhue

Publications and source records attributed to B Kerdelhue.

At least 37 records · Page 2Linked to original sources
PubMed1986

A substance P-containing hypothalamic neuronal system projects to the median eminence.

Immunoreactive substance P (SPi) was measured in the various hypothalamic structures and amygdala one week after placing a cut around the medial basal hypothalamus (MBH). SPi content decreased in the stalk-median eminence (SME), anterior and posterior parts of the arcuate nucleus (inside the isolated region) as well as in the paraventricular nucleus (outside the cut), while there was no change in the posteromedial amygdaloid nucleus. We suggest that there is a tuberoinfundibular neuronal system containing SPi with cell bodies in the MBH and terminals in the SME. In addition, nerve fibers containing SPi from outside the MBH may reach both the SME and the arcuate nucleus and might influence neuroendocrine regulation.

Animals↗
PubMed1985

Seasonal variations in plasma luteinizing hormone and testosterone levels in the European badger Meles meles L.

Although active spermatogenesis occurs throughout the year in the male European badger Meles meles L., seasonal fluctuations of testicular activity were observed. The present study compared the pattern of luteinizing hormone (LH) and testosterone (T) secretions throughout the annual cycle. LH secretion was investigated by means of a heterologous radioimmunoassay using anti-ovine LH beta antiserum and canine reference standard. Seasonal and nycthemeral changes in LH and T secretions were observed. During the year a period of maximal values for both hormones is well correlated with the breeding. Moreover, episodic LH releases occurs during the period of minimal testosterone values, indicating resumption of hypothalamo-pituitary activity well before the breeding period.

Animals↗
PubMed1985

Increase in brain and pituitary radioimmunoassayable gonadotropin releasing hormone (GnRH) in the European silver eel treated with sexual steroid or human chorionic gonadotropin.

In the female silver eel, a single estradiol 17 beta (E2) injection significantly increased radioimmunoassayable GnRH (IRGnRH) in the di- and mesencephalon and also in the telencephalon and olfactory lobes, during the first following days; after a chronic estradiol treatment, the pituitary IRGnRH was doubled. In the male silver eel, a single injection of human chorionic gonadotropin (hCG), which is able to induce a progressive testicular development and a durable increase in androgens production, produced a long-term effect on IRGnRH: IRGnRH was significantly increased in the same brain areas as in E2-treated females; a more important rise (10-fold) was observed for pituitary IRGnRH, probably reflecting the accumulation of GnRH in the axonal endings which directly innervate the pituitary in teleosts. These results suggest a positive effect of sexual steroids on GnRH synthesis but not release in the silver eel.

Animals↗
PubMed1985

Naloxone therapy of human septic shock.

A 0.01 and 0.1-mg/kg dose of iv naloxone was administered to seven patients in septic shock, in order to evaluate naloxone's hemodynamic effect and possible relation to changes in plasma beta-endorphin and catecholamine levels. Naloxone failed to modify cardiac index, blood pressure, heart rate, and systemic vascular resistance. Plasma beta-endorphin, norepinephrine, and epinephrine were elevated but did not change after naloxone administration. These results suggest that beta-endorphin release is a consequence but not a cause of shock, and that the beneficial hemodynamic effects of naloxone in animal studies could be related to species differences or nociceptive stimulations.

Adult↗
PubMed1985

[Direct effect of estradiol on the number of dopaminergic receptors in the anterior pituitary, in ovariectomized rats].

The effect of estradiol on anterior pituitary dopaminergic receptor content was studied in vivo and in vitro, in relation with the serum PRL secretion. A progressive and significant decrease in the number of these receptors was observed, a few hours before the serum release of PRL induced in ovariectomized females by a sequential treatment with different doses of estradiol benzoate. This decrease in the number of dopaminergic membrane receptors can be obtained as well in vitro, when anterior pituitaries, from ovariectomized rats, are incubated with 17 beta-estradiol. These results suggest that the stimulatory effect of estradiol on PRL secretion may be due, at least in part, to the direct "desensitization" to DA of anterior pituitary cells, which is produced by the decrease of dopaminergic receptor level.

Animals↗
PubMed1983

Biochemical and functional alterations of central GABA receptors during chronic estradiol treatment.

The characteristics of GABA and benzodiazepine receptors were examined in the hippocampus, striatum and cerebral cortex of female rats at various times (up to 9 months) after the subcutaneous implantation of an estradiol pellet (10 mg). A significant decrease in the Bmax of the high-affinity binding of [3H]muscimol to membranes from these 3 regions was detected as soon as one week after the implantation. Although the characteristics of the high-affinity binding of [3H]flunitrazepam remained unaffected during the whole treatment, the stimulatory effect of GABA (and muscimol) on this binding was significantly reduced by estrogenization. The changes in GABA receptor binding appeared functionally relevant since the elevation of striatal acetylcholine levels normally induced by the peripheral administration of muscimol (5 mg/kg) was significantly lower in estradiol-treated than in control female rats. In contrast to that observed in intact female rats, the implantation of estradiol in hypophysectomized animals did not affect the characteristics of [3H]muscimol binding to hippocampal, striatal and cortical membranes. [3H]muscimol binding was also unchanged in female rats implanted with estradiol and treated chronically with bromocriptine for 3 weeks. Since both hypophysectomy and the chronic administration of bromocriptine suppressed the hyperprolactinemia normally induced by estrogenization, the down-regulation of central GABA receptors very likely involved prolactin in intact animals implanted with 17-beta-estradiol.

Acetylcholine↗
PubMed1983

Circadian variations in beta-endorphin concentrations in pituitary and in some brain nuclei of the adult male rat.

Using both the 'punch' microdissection and a radioimmunological technique, circadian variations in beta-endorphin concentrations can be observed in the pituitary and in some discrete brain regions of the male rat (Wistar CFY). Animals were synchronized with light from 06.00 to 18.00 h, then darkness. Water and food were available ad libitum. Very well marked circadian rhythms were in evidence in the anterior lobe of the pituitary, the septum, the pons, the medulla oblongata and the cerebellum. There crest time locations were situated between 20.00 and 24.00 h. No significant circadian rhythms but biphasic variations were observed in the intermediate lobe of the pituitary, the POA, the thalamus, the central gray and the caudatus. There crest time locations were synchronized around 08.00 and 20.00 h. The most striking finding was that, regardless of the brain area investigated so far, maximal values were observed a short time after the beginning of the activity period of rats. This fact is identical with the one which has been observed for substance P and LH-RH contents in brain areas where these peptides are mostly present in nerve terminals in high concentrations.

Animals↗
PubMed1983

Modifications of the high and low affinity pituitary domperidone-binding sites in chronic estrogenized rats.

The effect of chronic estrogen treatment on the anterior pituitary domperidone-binding sites was studied in female rats. The rats were implanted from 1-6 months with a Silastic capsule containing 17 beta-estradiol. The Feldman analysis of [3H]domperidone binding to anterior pituitary membranes of control or estrogenized rats revealed the presence of two sites. The binding characteristics of the higher affinity site were identical for both groups (Kd of the high affinity site, 0.30-0.45 nM; maximum number of binding sites of the high affinity site, 74-95 fmol/mg protein); however, those of the lower affinity site were affected by the estrogen treatment: the Kd of the low affinity site increased from 17.4 +/- 3.2 to 41.5 +/- 9 (+/- SE) nM, and the maximum number of binding sites of the low affinity site increased from 214 +/- 22 to 343 +/- 35 fmol/mg protein. Thus, in chronic estrogenized rats, the total number of binding sites was increased by 54%. These changes, induced by chronic estrogenization, were reversible, since 2 weeks after removal of the 17 beta-estradiol pellet, the binding characteristics were no longer different from those observed in control rats. In contrast to chronic estrogen treatment, ovariectomy reduced markedly the total number of [3H]domperidone-binding sites in anterior pituitary membranes (-70%). Feldman analysis revealed that this reduction resulted from the complete disappearance of the low affinity sites in those membranes. No significant change in the binding characteristics of the high affinity site was detected in ovariectomized rats. Since estradiol induces a decrease in the anterior pituitary content of dopamine, a denervation supersensitivity-like mechanism might be responsible for the increase in pituitary domperidone-binding sites in estrogenized rats. Conversely, a hyposensitivity mechanism could be implicated in the decrease in the total number of the pituitary domperidone-binding sites in ovariectomized rats, since pituitary dopamine levels are increased in those animals. Whether the antidopaminergic properties of estrogen are also involved in this modulation after chronic estradiol treatment requires further investigation.

Animals↗
PubMed1982

Ultrastructural evidence for endogenous substance-P-like immunoreactivity in the rat pituitary gland.

Substance P (SP) is known to act on pituitary hormone release either at the hypothalamic level or directly at the pituitary level. In order to investigate whether SP is present in the pituitary gland and to localize the peptide at the cellular and subcellular levels, the immunocytological method was used. Rat pituitaries were fixed and frozen. Ultrathin sections, obtained by cryoultramicrotomy, were incubated with anti-SP serum. The antigen-antibody reaction was detected by 4-chloro-1-naphtol. SP immunoreactivity was observed both in the prolactin and in the gonadotropic cells, but not in the somatotropic, corticotropic and thyrotropic cells. In reactive cells, SP immunoreactivity was observed in the secretory granules, in the cytoplasm, and in the nucleus distributed all over the euchromatin near to the heterochromatin regions. No immunoreactivity was observed when nonimmune serum or anti-SP serum incubated with SP was used. No modification of the immunocytochemical reaction was observed when anti-SP serum incubated with somatostatin, gonado- or thyroliberin was used. These data (1) provide immunocytological evidence for the presence of SP in the pituitary gland; (2) indicate the presence of SP peptide in the gonadotropic and prolactin cells only. They support previous findings indicating that SP could have a direct effect at the pituitary level.

Animals↗
PubMed1981

Circadian variations in substance P, luliberin (LH-RH) and thyroliberin (TRH) contents in hypothalamic and extrahypothalamic brain nuclei of adult male rats.

Using both the 'punch' microdissection and radioimmunological techniques, circadian variations in substance P, luliberin (LH-RH) and thyroliberin (TRH) concentrations can be statistically validated in some discrete brain regions of the (Wistar CFY) male rat investigated in May. Animals were synchronized with light from 06.00 to 18.00 h and darkness. Water and food were available ad libitum. Very well marked circadian rhythms were in evidence in brain areas where the neuronal peptides investigated are mostly present in nerve terminals in high concentrations: medial basal hypothalamus for luliberin and thyroliberin and substantia nigra for substance P. On the contrary, no significant rhythms were detected in a number of areas where luliberin (preoptic area) or substance P (preoptic area, central gray matter, amygdala, globus pallidus) synthetizing perikarya are present. This suggests that at least luliberin and substance P are not secreted according to a circadian rhythmicity. The most striking finding was that crest time locations were situated at only two different times of the day: 14.00 h for thyroliberin and 20.00 h for substance P and luliberin. This suggests that circadian variations are not solely dependent on the activity of the endocrine system.

Amygdala↗
PubMed1981

In vitro LHRH release: correlation with the LH surge and alteration by a mammary carcinogen.

The releasability of LHRH from neurosecretory terminals, as assessed in vitro by depolarization of hypothalamic synaptosomes with elevated K+, varies as a function of the time of day in parallel with the LH surge. Pretreatment of ovariectomized female rats with dimethylbenz(a)anthracene (DMBA) results in a blockade of the estrogen-induced LH surge and a blunting of LHRH release as measured in vitro. An examination of the LHRH release process revealed that K+-stimulated release of particulate LHRH was inhibited by DMBA pretreatment while basal release of particulate LHRH and both basal and K+-stimulated release of soluble LHRH were not altered. These results suggest that release of particulate LHRH is closely coupled with the estrogen-induced LH surge.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1981

A dopaminergic binding site in the high speed supernatant of steer anterior pituitary homogenates.

The high speed supernatant fraction from homogenates of the steer anterior pituitary was shown to contain a high affinity (Kd = 0.10-0.20 nM), saturable (Bmax - 1.2-3.5 fmol/mg protein), stereoselective binding site for 3H-spiperone (3H-SPIP). The Kd (0.10 nM) calculated from the experimentally determined rate constants k1 and k2 was in excellent agreement with that derived from equilibrium measurements. The rank order of potencies of dopaminergic agents to compete for binding was consistent with known dopamine (DA) receptors. Soluble binding sites represented 3% of the total specific binding found in the anterior pituitary, and several lines of evidence suggested they were not due to enzymatic, mechanical or osmotic displacement of membrane receptors. Further studies are necessary to elucidate the possible significance of these soluble binding sites; however, this observation is intriguing since both DA and membrane bound DA receptors enter the cell.

Animals↗
PubMed1980

[Inhibition of the preovulatory secretion of gonadotropins by prolactin in rats seems to depend on the strain used].

Intraperitoneal injection of Rat Prolactin to cyclic female Rats results in preovulatory changes which depend on the strain of animals. Specifically, preovulatory surges of luteinizing hormone and follicle stimulating hormone were suppressed in Sprague-Dawley Rats while delayed but enhanced preovulatory surges of both gonadotropins were observed in Wistar strain.

Animals↗
PubMed1979

Topographical distribution of substance P in the cat substantia nigra.

The substance P (SP) content in cat substantia nigra (SN) was estimated by radioimmunoassay in microdiscs punched on successive frontal sections. Only slight differences were seen in the regional distribution of SP within the SN. The highest content was found in the pars reticulata (20.7 pmol/mg protein) which was two times higher than in the pars compacta and pars lateralis. Identical results were found in the right and left part of the SN. Out of this area, as pedunculus cerebri and zona incerta, very low concentrations were detected.

Animals↗