The circadian variation of prolactin in fetal sheep is affected by the seasons.

摘要: Plasma PRL concentration shows a circadian variation in fetal and adult sheep. In the sheep presence of this depends on season. paper we investigated whether season affects To that effect measured plasma every 2 h for 24 during summer, fall, winter three groups whose gestational ages ranged from 125-133 days. Mean (+/- SEM) concentrations were 352.8 +/- 65.0 ng/ml summer (n = 6), 98.7 12.9 fall 8), 10.5 2.6 4). A 24-h was detected [PRL (ng/ml) + 85.2 cos 15 (t - 18.5); P 0.007] 26.6 23.6); 0.041] but not winter. The mesor amplitude are higher than acrophases differ by 5 h, taking place at dusk close to midnight fall. These findings show sheep, responds seasons utero. signal triggering response is most likely photoperiod.