Demonstration of prolactin-releasing activity in the pigeon.

The capacity of the pigeon pituitary gland to release prolactin was investigated in vivo, to evaluate its hypothalamic regulation and to establish the dominant hypothalamic factor for prolactin secretion. After 3 days of systemic administration of some physiological and pharmacological agents, followed by 2 consecutive days of local intradermal injections of prolactin into their crop sacs, the crop mucosa was scraped, dried and weighed. The substances tested were: oestradiol and tamoxifen (antioestrogen), thyrotophin-releasing hormone (TRH) and anti-TRH serum, perphenazine (releases prolactin in mammals) and bromocriptine (suppresses prolactin in mammals). Prolactin and anti-prolactin serum were tested as controls. While prolactin markedly proliferated and anti-prolactin serum significantly inhibited the mucosal weight, oestradiol, TRH and perphenazine dramatically depressed proliferation of the mucosa, suggesting that prolactin secretion was inhibited. Tamoxifen, anti-TRH serum and bromocriptine significantly increased the proliferation of the crop mucosa, indicating an increase in the endogenous release of prolactin. Since the effect of these substances on prolactin release in the pigeon is the opposite from their well-established effects in mammals, these results suggest, in a specific and homologous model, that the dominating regulator for prolactin in the pigeon is contrary to that in the mammal, namely prolactin-releasing factor, and that TRH may play a significant role in the physiological regulation of prolactin secretion.

Effect of the timing of perphenazine administration on pregnancy in the rat.

Perphenazine in doses of 10--50 mg kg-1 day-1 given at the early stages of pregnancy delayed nidation up to day 8 of pregnancy. Once nidation had occurred the length of the rest of the gestation period was normal. Doses of up to 20 mg perphenazine kg-1 day-1, injected on days 1--7, prolonged gestation but the mothers and young were apparently normal; lower doses were effective only when treatment commenced soon after copulation. The delay in implantation of the ovum caused by perphenazine was corrected and and implantation was brought about immediately, by injection of 0.1 microgram oestradiol together with perphenazine. It is suggested that perphenazine delays and prevents implantation in rats by counteracting oestrogen release from the ovaries.

Quantitation of nitroglycerin in human blood after administration by sustained release.

Nitroglycerin was traced in the blood of 20 patients up to 4 h after oral administration of a sustained release preparation (Nitro-Mack Retard). The determination needs an extremely sensitive method using GLC-columns with 3% SE-30 (Packard) equipped with an electron capture detector.