Regulation of progesterone secretion by LH and prolactin during the first half of pregnancy in the mouse.

Pregnant mice were treated with antiserum to LH or bromocriptine to inhibit the activity of LH and prolactin, respectively. Luteal function was monitored by the radioimmunoassay of plasma progesterone. Bromocriptine treatment on Days 2 or 5 of pregnancy produced a rapid decrease in progesterone secretion, but had no effect on luteal function when given on Days 6, 7 or 8 of gestation.

Urotensin II: a somatostatin-like peptide in the caudal neurosecretory system of fishes.

Urotensin II, a peptide hormone from the caudal neurosecretory system of the teleost, Gillichthys mirabilis, was isolated by using classical chromatographic techniques and high-performance liquid chromatography (HPLC). Direct microtechniques for sequence determination were used to establish its structure. Urotensin II from Gillichthys is a 1363-dalton dodecapeptide with the amino acid sequence Ala-Gly-Thr-Ala-Asp-Cys-Phe-Trp-Lys-Tyr-Cys-Val.

Iontophoretic release of cyclic AMP and dispersion of melanosomes within a single melanophore.

Selective dispersion of melanosomes was often observed after iontophoretic injection of cyclic adenosine monophosphate (AMP) from a glass microelectrode positioned in a target melanophore in frog skin (as viewed from above through a microscope), with other melanophores in the field serving as controls. Because the skin has orderly arrays of several types of closely spaced cells, it is probable that at times the microelectrode also impales cells other than melanophores. When cyclic AMP injection inside a cell resulted in dispersion of melanosomes from a perinuclear position into dendritic processes, the onset of dispersion was relatively rapid, in many cases less than 4 min (mean time of onset, 5.

Plasma testosterone during pregnancy in the mouse.

Levels of plasma testosterone (T) were studied throughout pregnancy and on the day of parturition in selected strains of mice. A dramatic midpregnancy increase in androgen occurred in both strains examined (peak on day 9). A second increase in plasma T was found during the latter half of gestation (days 14-17), at which time plasma estradiol levels were elevated.

Plasma LH levels in the mare during the oestrous cycle.

Plasma levels of LH were determined by heterologous radioimmunoassay utilizing highly purified equine LH as standard. Samples were taken regularly from eleven mares for twenty-six oestrous cycles over a period of 10 weeks. The mean cycle length was 20-5 +/- 3-1 (S.