Histometric and histochemical studies of the hypothalamo-hypophyseal neurosecretory system of spontaneously hypertensive rats and rats with experimental hypertension.

Abstract

Histometric and histochemical studies were performed on the two hypothalamic neurosecretory nuclei (i.e., the supraoptic and paraventricular nuclei) and a few other hypothalamic nuclei in spontaneously hypertensive rats (S.H. rats) and in rats with various forms of experimental hypertension. 1. The following results were obtained in the histometric study. (1) The cellular and nuclear size of the nerve cells of the supraoptic nucleus was significantly greater in the S.H. rats than in the controls throughout the pre-hypertensive, initial and advanced stages of hypertension. In the advanced stage cells were 30% and nuclei 20% larger than normal ; in the pre-hypertensive stage 17% and 12% and in the initial stage 7% and 8% larger, respectively. The nuclear and cellular size of the nerve cells in the supraoptic nucleus tended to be greater than normal in the rats with DOCA-hypertension and with renal infarction hypertension, although the number of cases examined, was too small (3 cases) to be significant. (2) The paraventricular nucleus of the S.H. rats showed nearly the same results as the supraoptic nucleus with significant differences except for the nuclear size in the pre-hypertensive stage. The cells were 14-19% larger than normal in all the stages, the nuclei less than 11% larger than normal. In the rats with experimental hypertension cellular and nuclear size tended to be greater than in the controls, but the number of cases examined was small (3 cases). (3) The cellular size of the nerve cells in the ventromedial nucleus in these hypertensive animals remained normal. 2. The following results were obtained in the histochemical study of neurosecretory material. The amount of neurosecretory material in the hypothalamic neurosecretory nuclei and posterior pituitary of most of these hypertensive animals was not very different from that in the controls, although it was more prominent in some.