Control of prolactin secretion in teleosts, with special reference to Gillichthys mirabilis and Tilapia mossambica.

摘要: Two euryhaline teleosts, Gillichthys mirabilis (seawater) and Tilapia mossambica (fresh-water), were used to study the control of prolactin secretion. Cytological changes cells, plasma sodium measurements, densitometry disk electrophoretograms pituitary extracts incubation media provided data for study. When seawater are transferred a hypotonic environment, both morphological physiological indicate that secretion is activated dramatically, confirming role in adaptation hyposmotic conditions. Prolactin cells cytologically by transplantation as well injections reserpine 6-hydroxydopamine with significant elevation concentration. In contrast, inactivated injection l-DOPA. When fish bearing an autografted fresh water, decrease cell granules was observed. addition, estradiol-17β caused cytological activation ACTH cells. Pituitary glands incubated 3H-leucine 5–6 hr, radioactive present gland released medium measured. release directly stimulated low osmotic pressure medium. Addition dopamine amount into medium. The results at least four mechanisms may be involved teleosts: (1) inhibitory from hypothalamus presumably mediated aminergic fibers, (2) direct stimulation due decreasing pressure, (3) negative feedback either itself or increased level, (4) circulating estrogen.