Biomedical subjects
M Motta
Publications and source records attributed to M Motta.
Effects of 6- and 7-hydroxy metabolites of 3 beta,17 beta-dihydroxy-5 alpha-androstane on gonadotrophin and prolactin secretion and on sex accessories weight of male rats.
It has recently been shown that 3 beta,17 beta-dihydroxy-5 alpha-androstane (3 beta-diol), a known testosterone metabolite, may be further hydroxylated in position 6 and 7. Because of the possible involvement of 3 beta-diol in the control of gonadotrophin secretion, this work was aimed at investigating the effects of 3 beta,6 alpha,17 beta-trihydroxy-5 alpha-androstane (6 alpha-triol), 3 beta,7 alpha,17 beta-trihydroxy-5 alpha-androstane (7 alpha-triol), 3 beta,6 beta,17 beta-trihydroxy-5 alpha-androstane (6 beta-triol) and 3 beta,7 beta,17 beta-trihydroxy-5 alpha-androstane (7 beta-triol) on the secretion of LH, FSH and prolactin in long term castrated male rats. The four triols, 3 beta-diol and 3 alpha,17 beta-dihydroxy-5 alpha-androstane (3 alpha-diol), used for comparison, were given in a single subcutaneous dose of 2 mg/rat. Animals were killed 2, 5, 8 and 24 h after injection. None of the six steroids produces any significant effect on serum levels of FSH and prolactin at the 4 time intervals considered. On the contrary, LH levels are significantly reduced 2, 5 and 8 h after the injection of 7 beta-triol. This effect appears rapidly but is short lasting, since it disappears in the 24 h blood sample, 3 alpha-Diol also inhibits LH secretion but at later time intervals (8 and 24 h). None of the other steroids has any significant effect on serum LH levels. The four triols administered at the daily dose of 2 and 4 mg/rat for 6 days are totally ineffective in increasing the weight of the ventral prostate and of the seminal vesicles of prepuberal castrated male rats.
Mathematical analysis of antiserum titre and affinity in rabbits injected with 11 alpha OH-progesterone-hemisuccinate-BSA.
A mathematical procedure is presented here to determine the behaviour of antiserum titre in rabbits, after repeated injections of 11 alpha OH-Progesterone-hemisuccinate-BSA. By means of methods recently applied to the time series, the peaks of maximum response were determined. A common behaviour of rabbits was revealed for the delay times in the response after each booster injection. The titre and affinity of antiserum were determined by means of a special method for mathematical treatment of data in RIA analysis, which gives directly such parameters with a statistical interpretation.
Effect of long term administration of ovine prolactin on hypothalamic-pituitary testicular axis in rat.
The effect of hyperprolactinaemia on testicular morphology and on hypothalamic-pituitary-testicular axis was studied in adult male Wistar rats. Animals received ovine prolactin (oPRL) 200 micrograms twice daily s.c.) for 24 and 36 days and were killed by exanguination. Blood was collected for hormonal determinations and sex accessory glands were removed for histological studies. Circulating testosterone (T) and luteinizing hormone (LH) levels showed a significant reduction after 36 days of treatment whereas plasma follicle-stimulating hormone (FSH) levels were unchanged in all animals. No macroscopic or light microscopic histological modifications were observed in the testes. The present results, while excluding a direct effect of hyperprolactinaemia on seminiferous tubules, suggest that LH suppression is the consequence of a central effect of the ovine PRL long-term administration. The increased DA turnover in the hypothalamus suggested as inhibitory on GnRH neurons could account for this effect. The reduction of T levels seems to be mediated by the LH suppression, even though a direct effect of oPRL on Leydig cell receptors could be hypothesized.
Effect of opioid peptides on gonadotrophin secretion.
The intraventricular injection of 25 micrograms of Methionine-Enkephalin (Met-Enk) induces a significant increase of serum LH levels in long-term ovariectomized rats 15, 30 and 60 min following administration. The synthetic Met-Enk agonistic analogue [D-Ala2] methionine-Enkephalinamide ([D-Ala2]Met-Enk) also enhances significantly serum LH levels at 30 and 60 min; under the same experimental conditions neither Met-Enk nor [D-Ala2]Met-Enk modifies serum levels of FSH following intraventricular injections into ovariectomized animals. It is concluded that, under particular circumstances, opioid peptides of the Met-Enk family may stimulate LH release.
Effects of sex hormone metabolites on the secretion of gonadotropins.
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Neurotensin inhibits LH release.
The present studies were designed to assess the effect of neurotensin on the release of LH, FSH, and prolactin in long-term castrated female rats. The animals were implanted in the lateral ventricle of the brain wih a cannula to allow the administration of either neurotensin or the vehicle. The peptide (30 microgram, dissolved in saline) or the control saline solution was injected intraventricularly in a volume of 10 microliter following pentobarbital anesthesia. Blood samples were collected at sacrifice 15, 30 and 60 min after injection. A significant decrease of serum LH levels was already present in neurotensin-treated animals at 15 min, and was maintained up to the end of the experiment. This decrease was not accompanied by any change in FSH or prolactin secretion. The results suggest that this tridecapeptide participates in the control of LH release and provide new data on the separate control of the release of the two gonadotropins.
[The paraproteinemias. Clinico-biological study of hospital cases].
90 cases of paraproteinemia treated for 12 years, have been studied. The results, documented by a clinical and bio-humoral point of view, have been compared with those of largest and latest casistics. The Authors tried to see if there were some connections between serology, radiology, histology and clinical pictures of different cases of paraproteinemia both as far as the classes and the types. The clinical, registrar and hospital information about the homogeneous population of Saronno have been asked in order to consider the course of the illness continuously. Also the follow-up has been compared with the data of the specific literature. The obtained data are almost similar to those of the most accurate works which have been described.
Effect of met-enkephalin on portal insulin and glucose in the rat.
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A pharmacological analysis of the role of the amygdala in the control of gonadotropin and prolactin secretion.
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Effect of testosterone, its 5 alpha-reduced metabolites and the corresponding propionates on testosterone metabolism. I--In the hypothalamus and in the anterior pituitary.
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Effect of testosterone, its 5 alpha-reduced metabolites and the corresponding propionates on testosterone metabolism--II. In the ventral prostate and in the seminal vesicles.
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Effect of neurotensin on glucose and insulin portal blood levels in hyperglycemic rats.
A new multiple sampling technique for obtaining blood from the portal vein has been used to investigate the effects of neurotensin on insulin and glucose portal blood levels in rats rendered hyperglycemic by a constant glucose infusion. The peptide has been first injected acutely (2 microgram/rat iv), and then constantly infused (0.5 microgram/min for 55 min). The preliminary results indicate that no effect of the acute injection could be observed, but hyperglycemia and hyperinsulinemia were induced by the constant infusion of the peptide. It is suggested that neurotensin may stimulate the release of insulin probably through a direct mechanism.
Studies on the mode of action of androgens in the neuroendocrine tissues.
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Brain neurotransmitters, amygdala, and control of gonadotropin and prolactin secretion.
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In vivo effects of acetylcholine on LH secretion.
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Ultrashort feedback effects of releasing hormones.
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Control of pituitary FSH synthesis by hypothalamic factors in rats.
Electrolytic lesions placed in the median eminence of adult male rats are followed, in 7--10 days, by a significant decrease in pituitary FSH concentration. The intravenous injection of a hypothalamic extract prepared from normal animals induces, in 45 minutes, a significant increase in the amounts of FSH stored in the pituitary of median eminence-lesioned animals. The concentration of FSH in the pituitary of lesioned animals is also increased to normal by the intravenous injection of an extract prepared from the isolated hypothalamic island of animals previously submitted to a total "hypothalamic deafferentation", in spite of the fact that this does not contain any FSH-RF activity. It is suggested that the hypothalamus possesses separate humoral factors for the regulation of the release and of the synthesis of pituitary FSH.