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E Pattou

Publications and source records attributed to E Pattou.

26 records · Page 2Linked to original sources
PubMed1976

In vitro release of luteinizing hormone-releasing hormone (LHRH) from rat mediobasal hypothalamus: effects of potassium, calcium and dopamine.

A suitable preparation to study the effect of dopamine (DA) on in vitro LHRH secretion is presented. Enzymatic degradation of LHRH in the incubation medium is completely inhibited by bacitracin (2 X 10(-5) M). Ahigh potassium concentration (56mM) induces an increase in LHRH release from entire pieces of mediobasal hypothalamus (MBH), but not from a synaptosomal pellet; this release is inhibited when calcium is omitted. The depolarization-induced LHRH in the MBH. In contrast, DA (10(-6)M) is not effective in vitro on MBH from ovariectomized rats but induces a fast release of LHRH from MBH of normal male and estradiol-pretreated ovariectomized rats. The preparation presented here appears to be of great interest in investigating amine-steroid-LHRH interactions at the cellular level.

Animals↗
PubMed1975

Distribution of LH-RH in subcellular fractions of the basomedial hypothalamus.

Subcellular fractionation of the mediobasal hypothalamus (MBH) and other brain structures was achieved by differential and sucrose gradient centrifugation. The fractions were monitored by measuring lactate dehydrogenase (LDH) activity (a marker for the soluble cytoplasmic fraction) and by electron microscopic examination. The luteinizing-hormone-releasing-hormone (LH-RH) content of the fractions was evaluated both by bioassay and radioimmunoassay. Significant amounts of LH-RH were found only in the MBH and in an anterobasal location corresponding to the organum vasculosum of the lamina terminalis. Within these areas, LH-RH activity was present in the first supernatant (homogenate with the exclusion of the nuclear pellet). Seventy percent of the LH-RH activity was recovered in the crude mitochondrial fraction. After further fractionation on a sucrose gradient, the distribution of LH-RH was parallel with that of LDH activity. Since LDH is predominantly located in the synaptosomal soluble fraction, it is concluded that the vast majority of LH-RH is contained within nerve endings. This finding is consistent with cyto-immunological data on the distribution of the neuropeptide in the rat hypothalamus.

Animals↗
PubMed1975

Differential effects of hypothalamic deafferentation upon luteinizing hormone-releasing hormone in the median eminence and organum vasculosum of the lamina terminalis.

Complete deafferentation of the medial basal hypothalamus (MBH) was performed in male rats to ascertain the location of the cell bodies of nerve terminals containing luteinizing hormone-releasing hormone (LH-RH) in the external layer of the median eminence and the organum vasculosum of the lamina terminalis (OVLT). Radioimmunoassayable LH-RH in the MBH decreased to one-fourth of the control value 10 days after complete deafferentation, whereas, no change was observed in an area coextensive with the OVLT. Immunohistochemical staining of LH-RH appeared less intense within the median eminence of deafferented animals but was normal in the OVLT. These results suggest that the cell bodies of neurons producing LH-RH found in terminals in the OVLT lie outside the MBH. The possible explanations for the decreased LH-RH content in the median eminence are discussed.

Animals↗
PubMedDate not supplied

LHRH-like immunoreactivity in the human placenta is not identical to LHRH.

LHRH-like immunoreactive material was separated from human placental homogenates by chromatography and tested against two antibodies directed respectively against the C- or the N-terminus (N- and C-antibodies) of the synthetic peptide. Extraction yield was 94 per cent as assessed by the recovery of the radiolabelled LHRH added to the homogenates. Placental LHRH-like immunoreactivity in crude extracts appeared largely overestimated, due to interference of endogenous substances non-related to LHRH. After elimination of this contamination, a higher residual activity was detected with the C- than with the N-antibodies. Eluates tested under these conditions contained only 550 pg of LHRH-like material per kg of placenta. This concentration was comparable whether placental tissue had been sampled at 12 weeks of pregnancy or at the end of gestation. The corresponding peptides however neither co-eluted with synthetic LHRH nor with catabolite fragments of the peptide. It is concluded that the human placenta contains a lesser amount of LHRH-like material than anticipated on the basis of earlier results and that this material does not correspond to the native decapeptide.

Antibody Specificity↗
PubMedDate not supplied

Choline acetyltransferase and somatostatin levels in aged Microcebus murinus brain.

beta-Amyloid protein (beta-AP) deposits, analoguous to those found in Alzheimer's disease (AD) are observed in the brain of aging Microcebus murinus. Because choline acetyltransferase (ChAT) activity and somatostatin (SRIH) content are consistently decreased in AD, we tested whether such changes could be observed in middle aged to aged Microcebus cerebral cortex and whether they were accompanied by beta-AP deposits. A positive correlation was observed between age and ChAT activity. By HPLC, SRIH immunoreactivity eluted as four peaks, two of which being identical with SRIH-28 and SRIH-14 while the other two likely represented precursor forms. Cortical SRIH content was not significantly affected by age. ChAT activity and SRIH content were not significantly correlated. Amyloid angiopathy was observed in every brain examined and the presence of cortical lesions analoguous to senile plaques observed in the oldest case only which did not demonstrate important alterations in ChAT and somatostatin levels.

Aging↗
PubMedDate not supplied

[Effect of cerebral serotonin on cyclic LH release in rats].

An experimental increase in serotonin (5-HT) induced shortly before the "critical period" of ovulation control blocks the release of LH. Administration of a synthesis inhibitor of the amine p-chlorophenylalanine, (pCP) is ineffective when given during the critical period. However, pCP given in the evening of dioestrus II (18 to 24 hours before the "critical period") blocks ovulation. That 5-HT is specifically involved in this delayed effect of the drug is shown by the ability of increasing doses of 5-hydroxytryptophane (5-HTP) to induce with pCP a graded restoration of LH release when given together. This result, obtained in immature rats, has been confirmed in cyclic ones. A positive, permissive effect of 5-HT containing neurons on neural processes leading to LH release and ovulation is thus postulated. This action affects early stages of the LH release regulating mechanisms, in contrast to the classically described inhibiting effect of the amine, which blocks the actual release of LH-RH at the median eminence level during the critical period.

5-Hydroxytryptophan↗