LH and PRL secretion in ovariectomized spontaneously hypertensive rats

The pulsatile patterns of LH and PRL secretion, and effects of stress on these patterns were examined in ovariectomized normotensive Wistar, spontaneously hypertensive, and genetically matched normotensive Wistar Kyoto rats. Judged by the overall mean of PRL concentrations, PRL levels in spontaneously hypertensive rats were not different from those in Wistar Kyoto rats, but the pulse amplitudes as well as the overall mean concentrations were significantly greater in both Wistar Kyoto and spontaneously hypertensive rats than in Wistar rats. Increases in PRL release during immobilization stress in spontaneously hypertensive rats occurred earlier than in Wistar rats, but the peak levels were not different between the two animal groups, though significantly lower in Wistar Kyoto rats than in Wistar rats. Overall mean of LH concentrations was higher, but pulse amplitude was smaller in spontaneously hypertensive rats than in Wistar Kyoto rats, and in both groups significantly smaller than in Wistar rats. The decrease in LH release owing to stress was similar in all animal groups. A significant association between LH and PRL peaks was evident in all animals, although the rate of association was lowest in Wistar Kyoto rats. In conclusion, the central nervous system mechanisms for both LH and PRL secretion differ markedly in both spontaneously hypertensive and Wistar Kyoto rats from those in Wistar rats, and no specific difference was found in spontaneously hypertensive rats compared with Wistar Kyoto and Wistar rats as controls.