Mechanisms of PGF2 alpha action in functional luteolysis.

The luteolytic action of PGF2 alpha appears to be due to loss of gonadotropin support of corpus luteum function. This "chemical hypophysectomy" produced by PGF2 alpha in the rat has several components: 1. A rapid block of gonadotropin uptake in vivo by an unexplained mechanism.

Specific binding of prostaglandin F2 alpha to membranes of rat corpora lutea.

Prostaglandin F2 alpha (PGF2 alpha) binds specifically to a partially purified membrane preparation from rat corpora lutea. The high affinity, low capacity binding component asa a Kd = 4.7 nM and has a capacity of 0.

Action of gonadotropin-releasing hormone and its superactive analogues on the anterior pituitary: the mechanism of release and synthesis of gonadotropins.

The role of prostaglandins (PG), their active intermediates or the adenylcyclase-cyclic AMP system for gonadotropin release and/or synthesis was evaluated by administering gonadotropin-releasing hormone (Gn-RH) and its superactive analog to normal and aspirin-treated rats. Serum LH levels, anterior pituitary malondialdehyde (MDA) content and cyclic AMP (cAMP) levels were followed. The pituitaries stimulated with Gn-RH or its superactive analog yielded more MDA and cAMP than the controls.

Stimulation of gonadotrophs by pituitary portal vessel infusion of superactive LH-RH analogues: an ultrastructural study.

LH-RH or its superactive analogues were infused into pituitary portal vessels of adult male rats for 1 min; pituitaries were then fixed for routine electron microscopy 1 min, 30 min and 3 h after infusion. A maximal increase of granule release at 2 min. and a maximal increase in synthetic activity (i.

Localization of catecholamines in the eyes and other tissues of Aplysia.

A green fluorescence indicative of catecholamines (CA) was localized in the secondary cells (nonreceptor neurons), neuropile and optic nerve of the eye and other tissues in Aplysia by using the formaldehyde-induced fluorescence method for the demonstration of biogenic amines. The specificity of the induced fluorescence was confirmed by its absence in tissue not exposed to formaldehyde vapor, relatively rapid decay upon exposure to UV light and its chemical reduction by sodium borohydride. The fluorescence was greatly reduced in eyes treated with reserpine (depletes serotonin and catecholamines).

Ultrastructural observation of anterior pituitary gonadotrophs following hypophysial portal vessel infusion of luteinizing hormone-releasing hormone.

Luteinizing hormone-releasing hormone (LHRH) (50 ng) was infused with a microcannula into hypothalamo-hypophysial stalk portal vessels of adult male rats. Anterior pituitaries were prepared for electron microscopy at 1, 5, 10, 15, 30 and 60 minutes after infusion. Granule release (exocytosis) from gonadotrophs was stimulated within one minute.