Effect of constant light on the circadian rhythm of prolactin

Abstract
The different effects of equal periods of constant light (from days 1-065 or 70-135) upon the circadian rhythm of prolactin in male rats have been studied.Plasmatic levels of hormone have been analyzed at 5.00, 9.00, 12.00, 17.00, 21.00 and 24 h.65 and 135 day-old controls on a 12 h light/12 h darkness schedule show PRL surges at 17.00 h.These surges disappear in both groups when submitted to constant light.A global increase of PRL levels can be observed only in 135 day-old rats, which disappears 15 days after castration.This indicates testicular involvement in the hyperprolactinemia induced by constant light.
Keywords:
Light, Animals, Castration, Circadian Rhythm/radiation effects, Male, Prolactin/blood, Rats
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