The effects of electrical stimulation of the brain on the ovarian venous plasma concentrations of estradiol (E2) and progesterone (P) were investigated in female rats hypophysectomized and adrenalectomized at 1000 h on the day of proestrus. Stimulation was applied during the proestrous critical period under pentobarbital anesthesia, and contralateral ovarian venous blood was collected from 105-120 min after the stimulation. E2 and P concentrations, estimated by RIA, were significantly increased by stimulation of the medial basal prechiasmatic area (PVA), ventromedial hypothalamus, and areas in the mesencephalon and decreased by stimulation of the dorsal hippocampus, lateral amygdala, and mesencephalic areas. Ovarian blood flow was not affected by these stimulations. Ovarian nervotomy in the proestrous rats abolished E2 secretion induced by PVA stimulation. In intact proestrous rats, electrochemical stimulation of the PVA but not the preoptic suprachiasmatic area increased E2 and P concentrations, although stimulation of both areas commonly potentiated gonadotropin secretion. Present findings suggest that the efferent neural system from the brain to the ovaries is supplementary to the brain-pituitaryovarian hormonal mechanisms in the regulation of ovarian steroid secretion, and the system may be required for the adjustment of ovarian responsiveness and sensitivity to gonadotropins. In addition, evidence for neural feedback on basal FSH secretion in the ovarian-denervated proestrous rats is presented in this study. {Endocrinology 109: 136, 1981) I T HAS been demonstrated in rats that the cyclic alteration of ovarian steroid biosynthesis (1) and secretion (2, 3) are temporally related to the cyclic changes of gonadotropin secretion throughout the estrous cycle. The administration of gonadotropins to cyclic rats increased or decreased ovarian biosynthetic activity (1), and the effects were altered qualitatively and quantitatively during the estrous cycle (1, 4). However, it is still obscure whether the cyclic changes in ovarian steroid synthesis and release depend only upon gonadotropin secretion. Stimulation of the dorsal hippocampus (d-HPC) during the estrous cycle changed steroid biosynthetic activity without affecting gonadotropin secretion (4) or pituitary stalk blood LHRH concentration (5). More recently, d-HPC stimulation was shown to induce alterations in ovarian estrogen and progestin biosyntheses in pituitary-lesioned rabbits pretreated with 20a-hydroxyprogesterone (6). The above findings indicate the existence of other mechanisms besides the gonadotropin regulation of ovarian steroid synthesis and release.Recently, adrenergic and cholinergic projections to the

SummaryIn an attempt to clarify the nutritional enigma of the healthy strong physique of Papua New Guinea (PNG) highlanders who have a protein-deficient diet mainly composed of sweet potato, a pilot study was performed as follows with 10 volunteers of PNG highlanders, and with 8 Japanese controls, one group of whom took an experimental protein-deficient diet in Japan. 1. In 4 groups of subjects, i.e. adults of PNG highlanders, their children, Japanese controls who were having standard Japanese food (SPD), and those who were having a low protein diet (0.5g/kg) for 2 weeks (LPD), urea metabolism was investigated after oral administration of 15N urea. By tracing the cumulative excretion of 15N in urine successively for about 10 days after 15N urea administration, it was found that children of PNG highlanders can retain a large amount of 15N in the body, Japanese controls of LPD fairly well, PNG adult slightly and the Japanese controls of SPD the least of the four groups. It was demonstrated that the 15N atom% excess in the plasma protein of PNG adults, children, and Japanese control of LPD is maintained in the range of 0.02-0.05% fluctuating for 10 days after 15N urea administration. On the other hand, 15N atom% excess in plasma protein of Japanese control of SPD was within the scope of error (0.01%). 15N atom% excess in the lysine fraction of the hydrolysate of plasma protein was found in the range of 0.01-0.05% in a large number of cases of PNG subjects, and Japanese control of LPD, while it was not significantly detectable in Japanese

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