The bioactivity of human prolactin (hPRL) and human chorionic somatomammotropin (hCS) in the sera from the pregnant women (30-40weeks of gestation) and in the amniotic fluid (37-41 weeks of gestation) were determined individually by the bioassay for lactogenic hormones using rat lymphoma cell bioassay in combination with the antibody blocking method.
The bioactivity of hPRL in the pregnant sera ranged from 67 to 289ng/ml and in the amniotic fluid from 141 to 1603ng/ml. The ratio of the bioassay and RIA estimates of hPRL in the pregnant sera was 0.93±0.23 (mean±SD) and that of estimates of hPRL in the amniotic fluid was 1.04±0.26. These ratios are not significantly different from unity, which demonstrates that the bioactivity of hPRL is not significantly different from the immunoactivity.
The bioactivity of hCS in the pregnant sera ranged from 5.6 to 21.8μg/ml and in the amniotic fluid from 87 to 1274ng/ml. The ratio of the bioactivity and RIA estimates of hCS in the pregnant sera was 1.48±0.20 and that of estimates of hCS in the amniotic fluid was 1.32±0.21. These ratios are significantly higher than unity, which demonstrates that the bioactivity of hCS was significantly higher than the immunoactivity. This may be due to the impurity or relatively decreased bioactivity of the hCS standard.
This bioassay seems useful and convenient to measure the individual concentration of hPRL and hCS in the pregnant serum and in the amniotic fluid.

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High pressure liquid chromatography (HPLC, Toyo Soda TSK-GEL G3000 SW column) was used to analyse the properties of Estramustine binding protein (EBP) in the cytosol of rat dorsal prostate. There exist in the cytosol of rat dorsal prostate two binding components having a high affinity for Estramastine. When estimated by HPLC, the molecular weights of these Estramustine binding components are 45, 000-50, 000 and 25, 000-30, 000 daltons, respectively. The binding of 3H-Estramustine to a macromolecule with a molecular weight of 25, 000-30, 000 is more heat labile than binding of 3H-Estramustine to a macromolocule with a molecular weight of 45, 000-50, 000. The present study also demonstrates that the HPLC method offers higher resolution, smaller sample size and faster analysis than other methods used in binding studies.

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The alteration in levels of myosin light chain kinase and cyclic AMP-dependent protein kinase was studied in rabbit myometrium during pregnancy. The specific activity of myosin light chain kinase was 160.9±2.7, 128.1±3.5, and 126.5±4.4% at the 10th, 20th and 28th days after pregnancy, respectively, in comparison with the value seen in samples from non-pregnant rabbits. On the other hand, the specific activity of cyclic AMP-dependent protein kinase gradually decreased to 75.9±1.7, 58.7±3.5 and 36.9±1.9% of that of the control at each time with the increase in the time of gestation. The protein kinase inhibitor was not involved in the decrease in cyclic AMP-dependent protein kinase. These results suggest that the dissociation of the dynamic states of the two enzymes may make it possible for the myometrium to efficiently respond for contraction in the last stage of pregnancy.

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To get an electrophysiological basis for understanding the sexual and age-related changes in the brain mechanisms controlling gonadotropin secretion, we studied single unit responses to electrical stimulation in the preoptico-arcuate, amygdalo-preoptic and hippocampo-preoptic neural connections in the rat. Orthodromic unit responses to single pulse electrical stimulation were recorded in young mature and aged, male and female rats by post-stimulus histogram analysis.
Electrical stimulation of the medial preoptic area elicited responses in one-half of the hypothalamic arcuate neurons tested in female rats while the stimulation induced responses in less than one-third of the arcuate neurons in the male. The percentage of arcuate neurons responding to preoptic stimulation did not differ between young and aged animals. Stimulation of the medial amygdala evoked responses in a larger number of preoptic neurons in young mature rats than in aged animals in both sexes. There was no sexual difference in the number of responding neurons to amygdaloid stimulation. Percentages of preoptic neurons responding to the hippocampal stimulation were greater in young females showing regular estrous cycles than in males or aged females which showed constant estrous vaginal smears. In aged females whose vaginal cycles were induced by daily treatment with progesterone, more preoptic neurons responded to stimulation of the amygdala and the hippocampus than in aged constant estrous rats. The young cycling and aged progesteronerecycling rats had similar preoptic neuronal responses to the limbic stimulation. Stimulus thresholds for inducing these arcuate and preoptic unit responses were almost equivalent among different groups of animals. This suggests that the alteration in unit responses observed was not due to a change in neuronal excitability in the sites of stimulation in different animal groups. These results indicate that there are sex differences in the synaptic functions which transmit preoptic signals to the arcuate neurons and hippocampal impulses to the preoptic neurons. It is also suggested that the amygdalo-preoptic and hippocampopreoptic neural pathways may be functionally modified in aged rats because of the absence of estrous cycles.

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The effects of streptozotocin-induced diabetes mellitus on the hypothalamic-pituitarythyroid axis in rats were studied.
Streptozotocin (60mg/kg) was injected ip. Rats were decapitated at two and four weeks after the streptozotocin treatment. Thyrotropin releasing hormone (TRH), thyrotropin (TSH), thyroxine (T4), 3, 3', 5-triiodothyronine (T₃), 3, 3', 5'-triiodothyronine (rT₃), 3, 3'-diiodothyronine (3, 3'-T₂) and 3', 5'-diiodothyronine (3', 5'-T₂) were measured by means of the specific radioimmunoassay for each.
Immunoreactive TRH (ir-TRH) contents in the hypothalamus significantly decreased at four weeks (p<0.02). Basal TSH levels in plasma significantly decreased (p<0.005, p<0.001), and plasma ir-TRH and TSH responses to cold were significantly inhibited after the strepotozotocin treatment (p<0.001). The plasma TSH response to TRH was decreased, but not significantly. The plasma T₄ and T₃ levels fell significantly. RT3 did not change throughout the experiment. 3, 3'-T₂ levels in plasma fell significantly, whereas 3', 5'-T₂ increased. Blood glucose levels rose significantly after streptozotocin treatment, but insulin treatment led to partial restoration.
The findings suggest that streptozotocin-induced diabetes mellitus affects various sites of the hypothalamic-pituitary-thyroid axis in rats.

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Adrenocortical carcinoma rarely produces pure primary aldosteronism. We document the occurrence of such a case. Through tumor steroid analysis, we show that the content of aldosterone per gram of tumor tissue is diminished compared to aldosterone producing adenomas. We also demonstrate the occurrence of angiotensin II receptors on the tumor, a finding hitherto noted only on aldosterone producing adenomas.

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The effects of the catecholestrogen 2-hydroxyestradiol (250 and 500μg/day, each for 7 days) on plasma renin substrate (PRS), activity (PRA) and concentration (PRC) were studied in male rats as compared with those of estradiol (250μg/day, for 7 days) and vehicle alone (for 7days).
Pre-treatment levels of PRS, PRA, PRC and the PRA/PRC ratio were similar in four groups. After vehicle treatment, PRS, PRA, PRC and the PRA/PRC ratio remained unchanged. Estradiol treatment, however, produced an increase in PRS, an increase in PRA but no change in PRC. The PRA/PRC ratio after estradiol treatment was high. On the other hand, 2-hydroxyestradiol treatment caused no increase in PRS at a daily dose of 250μg and a slight but significant increase in PRS at a daily dose of 500μg. This treatment also produced increases in PRA as well as PRC at the two daily doses. These increases in PRA and PRC tended to be higher at a daily dose of 500μg than at a daily dose of 250μg. The PRA/PRC ratios after 2-hydroxyestradiol treatment were unaltered at the two daily doses.
It is concluded that, while 2-hydroxyestradiol is less active in increasing PRS than estradiol, the compound is capable of increasing PRC.

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Naloxone (an opiate antagonist) inhibited the black-background adaptation of bullfrog tadpoles Rana catesbeiana. The melanophore index (MI) of naloxone-injected tadpoles was significantly lower than that of controls 1hr after changing the background from white to black. Naloxone was not effective in lightening the skin color in the hypophysectomized tadpoles bearing a pituitary graft. Their skin color remained dark. Tadpoles injected with pimozide (a dopamine antagonist) or α-methyl-p-tyrosine (α-MPT, catecholamine synthesis inhibitor) simultaneously with naloxone showed significantly higher MI than that of the animals treated with naloxone alone. The present results seem to indicate that opioid peptides exert an influence on MSH release in background response of bullfrog tadpoles by modulating MSH release inhibiting activity of the hypothalamic dopamine neurons.

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Various doses (5mg, 12.5mg and 25mg) of angiotensin I converting enzyme inhibitor (SQ 14, 225, captopril) were administered to 8 patients with essential hypertension on a three-crossover study design, and the time course of mean blood pressure (MBP), plasma renin activity (PRA), plasma angiotensin converting enzyme activity (ACE-A), plasma cortisol (PC) and plasma aldosterone (PA) were determined following administration of the drug. MBP fell in a dose dependent manner, and PRA showed a minor but significant increases in cases receiving 5 and 12.5mg of the drug. A large and significant increase in PRA was observed following 25mg of captopril. ACE-A was also reduced in a dose dependent manner. There was no difference between changes in PC at any of the three dose levels. The serum potassium concentration was determined before and 3h after 25mg of captopril treatment and no significant change was observed. In spite of the dose dependent and theoretical changes in the above parameters, lowered responses of PA to each dose of the drug were shown in reverse order against an increasing dose. That is to say, the grade of fall in PA following 25mg of captopril was smaller than that following the other doses of the drug, and 5mg induced a greater decrease in PA than 12.5mg.
Based on these findings, the relatively high dose of captopril in the present study was apparently more effective in increasing some factors which suppressed reduction of PA by a fall in angiotensin II than a low dose of the drug.

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A 37-year-old woman with postoperative hypoparathyroidism had hypertension, and elevated plasma renin activity (PRA) and subsequent hyperaldosteronism during a twomonth hypercalcemic period caused by vitamin D and excessive calcium supplements. The hypertension with elevated PRA, however, was resistant to the angiotensin II (AII) analog [Sar¹, Ile⁸] AII. PRA further increased and plasma aldosterone decreased in response to the [Sar¹, Ile⁸] AII. When the patient became normocalcemic, normotensive and normoreninemic, calcium gluconate (5mg calcium/kg/h) was infused for one hour. The calcium infusion reproduced hypercalcemic hypertension mediated by an increase in total peripheral resistance.
These observations suggest that the hypertension observed while taking vitamin D and excessive calcium supplements may be caused by a direct effect of calcium on peripheral blood vessels and the renin-angiotensin system may play a negligible role.

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