Evidence for direct inhibition of ovarian function by prolactin

Direct effect of prolactin, induced by TRH injection, on ovarian oestradiol secretion in the ewe

“…The role of prolactin in the control of ovarian follicle growth and development in the sheep remains unknown (see McNeilly, Glasier, Jonassen & Howie, 1982b). During the oestrous cycle plasma levels of prolactin show no significant trend until an increase coincident with oestrus and ovulation.…”

Effect of pregnancy, injection of oestradiol benzoate or hCG on steroid concentration and release by pig luteal cells

“…An indirect effect of exogenous oestradiol on steroid production by luteal cells of oestradioltreated pigs cannot be excluded. Ziecik et al (1986) showed that the concentration of prolactin in oestradiol-treated pigs was 7-20 times higher than in pregnant pigs and therefore this elevated prolactin level may have suppressed luteal steroidogenesis (McNeiUy et al, 1982;Przala et al, 1984a, b). The high oestradiol-17ß content in the plasma and luteal tissue of oestradiol-treated sows in the present study is likely to be a consequence of oestradiol binding by the oestradiol antiserum (cross-reactivity = 83%).…”

Seasonal endocrine cycles in the European hedgehog, Erinaceus europaeus

“…The wide-ranging functions of prolactin (McNeiUy, 1980;Knight & Peaker, 1982;McNeiUy et al, 1982;Bartlet, 1985;Gromdzka-Ostrowska et al, 1985) makes the interpretation of the sig¬ nificance of elevated prolactin values during winter difficult, although prolactin is implicated in induced ovulation (Saboureau & Castaing, 1985) in hedgehogs. Correlations between prolactin and photoperiod and ambient temperature suggest that prolactin is involved in the environmental regulation of metabolic and reproductive cycles of the hedgehog.…”