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MRIDULA CHOWDHURY
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E. STEINBERGER
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SUMMARY

Levels of LH and FSH were measured by radioimmunoassay in serum, pituitary and placental tissues of male and female foetal and newborn rats. No gonadotrophins were detected in placental tissues or amniotic fluid. In the male, pituitary FSH and LH were first detected on day 17 of gestation. Gonadotrophins could not be detected in any female tissues until birth. In male foetuses the highest levels of both LH and FSH in the circulation were found on day 16 of foetal life; subsequently the levels decreased dramatically.

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MRIDULA CHOWDHURY
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EMIL STEINBERGER
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A method has been developed for studying biosynthesis of FSH in the rat pituitary in vitro. Anterior pituitary glands were incubated with [3H]leucine; a specific and sensitive immunoprecipitation technique was used to isolate FSH from the pituitary homogenate. Total FSH content of the samples was measured by a double-antibody radioimmunoassay technique. Using this technique, a comparative study of LH and FSH synthesis in the same pituitary of adult male rats incubated for various intervals (0·5–6 h) was done. Increased incorporation of [3H]leucine into both LH and FSH with time was noted. The rate and amount of [3H]leucine incorporation into FSH was found to be higher than that into LH, indicating that either the rate of FSH synthesis is higher than that of LH or FSH has more leucine residues than LH. Greater susceptibility of LH to degradation by endogenous proteases during dialysis may also reflect less incorporation of [3H]leucine into LH. This method provides a reliable tool for evaluating FSH synthesis under various experimental conditions.

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A. S. BERKOWITZ
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J. A. LLOYD
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MRIDULA CHOWDHURY
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The relationship between the method of exsanguination and the serum concentration of gonadotrophins was investigated in male house mice. Mice were killed 21–99 days post partum by ether anaesthesia and cardiac puncture, or by decapitation. Results of gonadotrophin radioimmunoassays indicated that titres of serum FSH were not affected by the method of exsanguination, while concentrations of serum LH were significantly raised when blood was collected by ether anaesthesia and cardiac puncture. Serum FSH in an inbred strain of mice peaked at 21 days post partum and declined steadily to a relatively constant pubertal and postpubertal level. Concentrations of serum LH were variable during the prepubertal period with a peak occurring 31–35 days post partum. Extremely high titres of FSH on days 21–35 post partum indicated that mice in this study might be relatively insensitive to FSH in the prepubertal period.

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Mridula Chowdhury
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S. N. Kabir
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A. K. Pal
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Anita Pakrashi
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Daily oral administration of p-coumaric acid (PCA) at a dose of 50 mg/kg body wt for 21 days to adult male mice caused a dramatic reduction in serum prolactin concentrations. A significant fall in testicular LH binding was also observed after PCA treatment. Complete recovery of testicular LH binding was obtained by daily administration of prolactin (500 μg/mouse) when given simultaneously from day 9 of PCA treatment. A lower daily dose of prolactin (250 μg) was found to be ineffective.

Scatchard analysis of binding data suggested a decrease in the number of testicular LH binding sites after PCA treatment whereas the affinity constant was unchanged.

These results provide direct evidence for an inhibitory effect of PCA on prolactin secretion and also provide additional evidence in favour of a role of prolactin in the modulation of LH receptors.

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