In vitro effect of LH-releasing factor on the content of cyclic cytidine 3' 5' monophosphate (c-CMP) in the rat anterior pituitary.

The effect of LH-RF on pituitary content of cyclic cytidine 3' 5' monophosphate (c-CMP), one of the newly detected cyclic nucleotides, was examined by the RIA procedure. In results showed that the pituitary content of c-CMP was lower than in various other organs of the rat. When incubated in vitro in the presence of 0.5 ng LH-RF/ml incubation medium, c-CMP content of the anterior pituitaries was reduced slightly, but the difference was not statistically significant when compared with the controls. No difference in c-CMP content was observed between the controls and the 5 ng LH-RF/ml group. C-CMP content in the rat anterior pituitary tissue did not change significantly during an in vitro time-course study (5, 15, and 30 min.) in the presence of 5 ng LH-RF/ml. In contrast, c-AMP content of the pituitary was significantly (P less than 0.05) elevated by the stimulation of 5 ng of LH-RF/ml at a 15 minutes of incubation. These data suggest that c-CMP content, unlike c-AMP, might not be changed significantly by hypothalamic gonadotropin releasing hormone.