The effects of a sudden decrease or increase in daylength on prolactin secretion in the ram

in Reproduction

Summary. Six adult Soay rams were preconditioned to an artificial lighting regimen of alternating 4-month periods of long (16L:8D) and short days (8L:16D) for at least 10 months before blood samples were collected at hourly intervals for 24 h at various times. The abrupt change from long to short days resulted in a progressive decrease in plasma levels of prolactin, while that from short to long days had the reverse effect; the first response to the light changes was rapid, beginning within 6 days. During the periods of high secretion there was a 24-h cycle in plasma prolactin concentrations, with a peak in both the early dark and early light phases of each day. Changes in the relative magnitude of these peaks were observed in relation to the long-term alteration in prolactin secretion. Plasma levels of FSH were also measured and a close inverse relationship between gonadotrophin and prolactin secretion was observed.

If the inline PDF is not rendering correctly, you can download the PDF file here.

 

    Society for Reproduction and Fertility

All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 116 46 5
PDF Downloads 435 141 3