Rat RFRP-3 alters hypothalamic GHRH expression and growth hormone secretion but does not affect KiSS-1 gene expression or the onset of puberty in male rats.

Background/aims: RFRP-3 is a recently described neuropeptide that influences a variety of physiologic factors, including the inhibition of gonadotropin secretion and reproductive behaviors. We hypothesized that endogenous RFRP-3 could function to inhibit the onset of puberty in young male rats.

Methods: To test this hypothesis, we first placed cannulas into the third ventricle of 24-day-old male rat pups.

Design, synthesis, and biological testing of pyrazoline derivatives of combretastatin-A4.

Fourteen N-acetylated and non-acetylated 3,4,5-tri- or 2,5-dimethoxypyrazoline analogs of combretastatin-A4 (1) were synthesized. A non-acetylated derivative (5a) with the same substituents as CA-4 (1) was the most active compound in the series, with IC(50) values of 2.1 and 0.

Rat RFamide-related peptide-3 stimulates GH secretion, inhibits LH secretion, and has variable effects on sex behavior in the adult male rat.

A recently described avian neuropeptide, gonadotropin inhibitory hormone (GnIH), has been shown to have seasonal regulatory effects on the hypothalamic-pituitary-gonadotropin axis (HPG) in several avian species. In the bird, GnIH expression is increased during the photorefractory period and has inhibitory effects on the HPG. A recently described mammalian neuropeptide, RF-amide-related peptide-3 (RFRP-3), may be genetically related and functionally similar to this avian neuropeptide.

Galanin-like peptide rescues reproductive function in the diabetic rat.

Galanin-like peptide (GALP) is expressed in the hypothalamic arcuate nucleus and is regulated by leptin and insulin. Centrally administered GALP stimulates gonadotropin secretion and sexual behavior in the rat. Type 1 diabetes is associated with reduced expression of GALP, as well as an overall decline in reproductive function.