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Biomedical subjects

M Vincens

Publications and source records attributed to M Vincens.

36 records · Page 2Linked to original sources

Differential effects of exogenous oestradiol and progesterone on mood in post-menopausal women: individual dose/effect relationship.

This study reports on 56 women who volunteered for consultation at a gynaecological hospital for their climacteric symptoms. The stability of their low oestradiol and high gonadotrophin plasma levels was controlled first. Afterwards they were treated for 3 mth with natural oestradiol (percutaneously). Once the plasma oestradiol levels were proved to be stable during the treatment, natural progesterone was also administered (orally) the last 10 days of treatment. As observed with all steroid administration, the same therapeutic regimen induced different individual plasma levels of the natural steroids. The relationship between mood and plasma levels was as follows. Moderate depressive symptoms were correlated to the lowest plasma oestradiol level, before and after treatment. Only when a moderate increase in oestradiol level was induced did the oestradiol treatment itself lead to a pleasant feeling of well-being. When an excessive increase was induced by the treatment, most of the women complained of unpleasant side effects, mostly irritability and aggressiveness. Progesterone had very few psychological effects if oestradiol levels were low or slightly increased. When plasma oestradiol was high, a moderate elevation of plasma progesterone induced a pleasant tranquillizing effect. A massive elevation of plasma progesterone levels immediately induced an inadequate hypnotic effect, sometimes with dizziness. Therefore, therapeutic administrations of natural steroids appear to strongly influence the mood and behaviour of post-menopausal women. However, the expected pleasant effect could not be successfully achieved without a careful adaptation of the correct dosage to each individual patient.

Affective Symptoms↗

Exaggerated prolactin response of thyrotropin-releasing hormone in women with anovulatory cycles: possible role of endogenous estrogens and effect of bromocriptine.

Twenty-one women 18 to 36 years old, presenting with chronic anovulation, were compared with 10 normally cycling women. The patients were characterized by low progesterone (P) levels (0.93 +/- 0.14 ng/ml versus 15.5 +/- 1.4 in controls), whereas 17 beta-estradiol (E2) was moderately decreased (110.2 +/- 8.3 pg/ml versus 162.8 +/- 14.5 in controls) realizing a relative hyperestrogenism. Basal prolactin (PRL) levels were not elevated (12.1 +/- 0.97 ng/ml versus 9.2 +/- 0.7 in controls), but after thyrotropin-releasing hormone (TRH) stimulation an exaggerated response was observed (114.5 +/- 7 ng/ml versus 55.8 +/- 9 in controls). Patients were treated with bromocriptine (1.25 mg 2 times a day) for 3 months. Fifteen responded with ovulatory cycles, and five became pregnant. Progesterone increased significantly (10.2 +/- 1.3 ng/ml), whereas in patients who did not ovulate P increased only slightly (1.56 +/- 0.18 ng/ml). The particular endocrine profile of these patients (P/E2 imbalance) realizing relative hyperestrogenism may be responsible for the exaggerated PRL response to TRH. Bromocriptine, in reducing this transient, or masked, hyperprolactinemia, allows in many patients the return to ovulatory cycles. This mechanism may be one of the possible pathways leading to chronic functional or organic hyperprolactinemia.

Adolescent↗

Modulation of central GABAA receptor complex by somatostatin: a pharmacological study.

The goal of the present study was to determine the possible interactions between somatostatin (SST) and gamma-aminobutyric acid (GABA). We thus investigated the SST interaction with [35S]-tertiary butylbicyclophosphorothionate (TBPS) binding sites of the cortical and hippocampal regions of the rat brain. The method used to identify such effects is in vitro quantitative autoradiography. Thus, the binding of the cage convulsant [35S]-TBPS to a picrotoxin-sensitive site in the rat brain was used to investigate the modulatory action of SST on the GABAA receptor complex. The addition of the peptide to the incubation medium results in a dose-dependent inhibition of [35S]-TBPS in cortical and hippocampal structures. Detailed analysis showed a dose-related effect of SST with relative potencies comparable to those observed for 5 alpha 3 alpha P and 5 beta 3 alpha P. In addition, these neurosteroids were able to enhance the efficacy of SST in inhibiting [35S]-TBPS binding. The efficacy of SST in enhancing the inhibitory action of neurosteroids was also evidenced. Furthermore, SST seems to mimic the effects of these neurosteroids as well as GABA and picrotoxin on [35S]-TBPS binding to the rat brain in every context examined. This suggests that somatostatin allosterically modifies [35S]-TBPS binding through a mechanism similar to that of GABA. On the other hand, a possible action of SST via transduction systems on the GABAA receptor complex could also be suggested. These results illustrate the importance of interactions in SST-mediated GABA transmission in these brain regions.

Animals↗