Depletion of Prolactin-Inhibiting Activity of Rat Hypothalamus by Estradiol or Suckling Stimulus11

Oestrogen-Induced Hyperprolactinaemia in the Rat: Reduced Concentrations of Hypothalamic Dopamine and the Effects of Bromocriptine

“…It has also been proposed that central serotoninergic neurones mediate the effect of oestrogen on prolactin release (Caligaris and Taleisnil( 1974). Oestrogen administration depresses 'prolactin-inhibiting factor' activity in the rat hypothalamus (Ratner and Meites 1964) and since prolactin release is tonically inhibited via hypothalamic dopamine (DA) pathways which have been shown to be subject to negative feedback by prolactin, attention has recently been directed toward the role of DA in oestrogen-induced hyperprolactinaemia (Eikenburg et al 1977). Eikenburg et al (1977) showed in rats that treatment for 5 days with oestrogen resulted in approximately threefold increases in serum prolactin and increased DA turnover in the median eminence but no changes were seen in DA concentrations.…”

Mitotic Activity in the Adenohypophysis of Pregnant and Lactating Rabbits

“…There is evidence suggesting that, in pregnancy and lactation, oestrogen (Meites & Nicoli, 1966), somatotrophin (Grosvenor & Turner, 1959), and suckling (Tindal, 1967;Grosvenor, Krulich & McCann, 1968) may also be involved in some species in the regulation of the synthesis and release of prolactin. For example, the release and/or the synthesis of the prolactininhibiting factor of the hypothalamus appears to be suppressed by oestrogen and by suckling (Ratner & Meites, 1964;Grosvenor, Mena, Dhariwal & McCann, 1967). In addition, both oestrogen and somatotrophin may have a direct mitogenic action on the adenohypophysial cells.…”

Prolactin and LH release in response to LH-RH and TRH in ewes during dioestrus, pregnancy and post partum

“…Both progesterone and oestradiol can inhibit the pulsatile release of LH (Diekman & Malven, 1973;Coppings & Malven, 1976;Hauger, Karsch & Foster, 1977), so that if the pulsatile release of LH reflects the pulsatile secretion of LH-RH (Lincoln & Short, 1981), pituitary LH depletion in pregnant and progesterone-oestrogen-treated ewes may be due to inadequate LH-RH action on the pituitary. In respect of prolactin, evidence from rats suggests that oestrogen acts at hypothalamic (Ratner & Meites, 1964;Fuxe, Hokfelt & Nilsson, 1969;Ramirez & McCann, 1964) and pituitary sites (Wolfe & Chadwick, 1936;Nicoli & Meites, 1964;Haug & Gautvik, 1976) (Chamley et al, 1974a;Chamley, Findlay, Jonas, Cumming & Goding, 1974b;Jenkin et al, 1977), there is only a parallel change in pituitary LH content (Chamley et al, 1976).…”