Effect of melatonin implantation on the seasonal variation of FSH secretion in the male blue fox (Alopex lagopus)
A heterologous radioimmunoassay system developed for the sheep was shown to measure FSH in the plasma of the blue fox. FSH concentrations throughout the year showed a circannual rhythm with the highest values (61 ·6 ± 14·8 ng/ml) occurring shortly before or at the onset of the mating season, a patte...
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Published in | Journal of reproduction & fertility Vol. 83; no. 1; pp. 345 - 354 |
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Main Authors | , , , , , |
Format | Journal Article |
Language | English |
Published |
England
Society for Reproduction and Fertility
01.05.1988
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Subjects | |
Online Access | Get full text |
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Summary: | A heterologous radioimmunoassay system developed for the sheep was shown to measure FSH in the plasma of the blue fox. FSH
concentrations throughout the year showed a circannual rhythm with the highest values (61 ·6 ± 14·8 ng/ml) occurring shortly
before or at the onset of the mating season, a pattern similar to that of LH. The concentration of FSH then declined when
androgen concentrations and testicular development were maximal at the time of the mating season (March to May). Thereafter,
concentrations remained low (25·2 ± 4·1 ng/ml) in contrast to those of LH. Implantation of melatonin in August and in February
maintained high plasma values of FSH after the mating season (142·3 ± 16·5 ng/ml) in association with a maintenance of testicular
development and of the winter coat. The spring rise of prolactin was suppressed by melatonin treatment. The release of FSH
after LHRH injection was also increased during this post-mating period in melatonin-treated animals, in contrast to the response
of the control animals which remained low or undetectable.
These results suggest that changes both in the secretions of FSH and prolactin may be involved in the prolongation of testicular
activity and in the suppression of the spring moult after melatonin administration.
Keywords: blue fox; FSH; melatonin; LHRH; seasonal cycle |
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ISSN: | 0022-4251 1470-1626 1741-7899 |
DOI: | 10.1530/jrf.0.0830345 |