Studies were done to determine the role of endogenous prostaglandins (PGs) for norepinephrine (NE) clearance in 10 male borderline hypertensives (BHT) (age : 20-28) and six age-matched male normotensives (NT). Two experimental protocols were followed in these subjects : 10 min orthostasis with blood sampling (protocol I), and 100 ng/kg/min of L-NE infusion for 60 min at supine position. Blood was collected from indwelling catheter at every min for 10 min after stopping the NE infusion (protocol II). Plasma NE was measured by THI method using HPLC. Disappearance curve of plasma NE was analyzed following the two compartment open model. The orthostasis and the steady state NE infusion were repeated after 150 mg/day of indomethacin (Ind) for three days. There were significant increases in plasma NE after orthostasis in both groups : from 180.8 ± 28.0 pg/ml to 346.2 ± 78.0 pg/ml (p<0.05) in NT and from 120.1 ± 12.8 pg/ml to 289.6 ± 20.3 pg/ml (p<0.001) in BHT, but there were no significant differences between the two groups. Ind pretreatment did not alter these responses. The calculated half-time of the first exponential phase (T1/2) was 1.50 ± 0.07 min in NT which decreased to 0.98 ± 0.10 min (p<0.05) after Ind pretreatment. In BHT, T1/2 was 1.03 ± 0.08 min (p<0.01 vs NT), which was not significantly changed after Ind. These results may suggest that endogenous PGs have some role (s) in NT for NE clearance, probably exerting inhibitory action on neuronal uptake. In BHT, neuronal uptake of NE is increased, probably due to an adaptation mechanism to elevated blood pressure.

View full abstract

Substances which suppressed the effect of gonadotropin in the rat were obtained from hop. These biologically active substances were fractionated from the hop cone, from which lipophilic components (total resins) were removed with acetone. They were water soluble, 70,000-80,000 in molecular weight and were composed mainly of neutral sugars and uronic acid.
Administration of the substances to immature rats primed with pregnant mare's serum gonadotropin (PMS) resulted in the following : a significant decrease of ovarian weight gain, whereas there was no change in uterine weight gain, and significant reductions of serum LH and progesterone from cultured luteal rat cells.

View full abstract

The secretory responses of the anterior pituitary hormone to physiological stress were studied in healthy male volunteers. Measurements of blood LH, FSH, Prolactin, GH, ACTH, lactate, pyruvate and hematocrit were made from blood samples taken at rest, after 15 minutes at sea level, and at an altitude of 4000 m and 5500 m modulated in a climatecontrolled room.
The results are summarized as follows :
1) Blood levels of Prolactin and ACTH were increased after exercise at a high altitude.
2) Blood levels of LH and FSH after exercise at each altitude were not significantly different from those at rest.
3) Blood GH level was increased after exercise at any altitude.
4) Blood levels of lactate and pyruvate were increased after exercise at any altitude.
These results suggest that the secretory response of the anterior pituitary hormone to physiological stress is prominent in Prolactin, GH and ACTH but not in FSH and LH.

View full abstract

Measurement of serum concentrations of free triiodothyronine (FT₃) is considered to be an accurate index of thyroid function in the patient. In this study, we measured serum concentrations of FT₃, free thyroxine (FT₄) and reverse triiodothyronine (rT₃) by radioimmunoassay in blood samples taken from the navel cord of 20 newborns as well as 20 nonpregnant women, 20 pregnant women, 10 patients with liver diseases, 25 patients with diabetes mellitus, 65 patients with hyperthyroidism, 30 patients with primary hypothyroidism and 29 normal subjects.
In pregnant women, serum FT₃ and FT₄ levels gradually decreased as the pregnancy progressed. In cord blood, FT₃ levels were less than a quarter of the values found during the first trimester of pregnancy or that of non-pregnant women, whereas serum rT₃ levels were drastically increased.
In chronic hepatitis, liver cirrhosis and diabetes mellitus, serum FT₃ and FT₄ levels were significantly lower than that in the controls.
In thyroid diseases, serum FT₃ levels varied parallel to other thyroid hormone levels. In primary hypothyroidism, however, serum FT₃ levels were still lower than these in the controls after treatment with 1-thyroxine, whereas other thyroid hormone levels and TSH levels returned to control levels.
The remarkable decrease in serum FT₃ and the increase in serum rT₃ observed in pregnant women and especially in fetuses may imply that even a low serum FT₃ level is enough to keep intracellular metabolism in a euthyroid state. Still lowered FT₃ levels in primary hypothyroidism even after treatment with 1-thyroxine suggest that in order to treat the hypothyroid patient sufficiently, it is necessary to normalize the serum FT₃ levels and that, in fact, the serum FT₃ level is a more useful indicator for medication in primary hypothyroidism.

View full abstract

Serum somatomedin (SM) activity by bioassay was measured in 46 idiopathic pituitary dwarfs before and during long-term hGH treatment. The mean (± SD) pretreatment SM activity was 0.38 ± 0.17 U/ml. The mean (± SD) pretreatment annual growth rate was 3.4 ± 1.0 cm/year. None of the patients had a SM activity within the normal range of age-matched controls. The mean SM activity 1 day post GH was 1.11 ± 0.28 U/ml. Neither the mean SM activity nor the growth rate during the entire treatment period up to 8 years decreased with the duration of the treatment, always being more than 1.0 U/ml and 5.0 cm/year respectively. With respect to normal data for chronological and bone age separately, 43.3% and 60% of the SM activity in the patients during hGH treatment attained the levels of age-matched normal controls. The increase in SM activity in the patients with treatment was not related to their growth rate. SM activity measured by bioassay is useful for evaluating clinical response to hGH therapy.

View full abstract

It is well-known that the hypothalamus predominantly exerts an inhibitory control on prolactin secretion and that dopamine (DA) is the main prolactin inhibiting factor (PIF). In addition, the hypothalamus contains prolactin-releasing factors (PRF). Thyrotropinreleasing hormone (TRH), vasoactive intestinal polypeptide (VIP) and peptide-histidineisoleucine (PHI) are the components of PRF. However, the detailed mechanism by which the peptides release prolactin (PRL) at the pituitary level is still unknown. Therefore, in this paper, an in vitro perifusion system using the cell column of cultured rat pituitary cells attached on Cytodex beads was employed to investigate the mechanism of PRL release.
The rat anterior pituitary cells were isolated using collagenase, and the dispersed pituitary cells were cultured with swollen Cytodex beads in Dulbecco's modified Eagle medium (DMEM) containing fetal calf serum at 37°C in 5% CO2 and 95% air for 2-3 days. The cultured anterior pituitary cells attached on Cytodex beads were packed in a column and perifused with DMEM at a constant flow rate of 0.4 ml/min using a peristaltic pump.
The following results were obtained.
1) A five minute perifusion with 100 pg/ml to 100 ng/ml TRH caused a significant increase of PRL in a dose-related manner.
2) A continuous perifusion with 2 ng/ml or 10 ng/ml DA inhibited PRL release in a dose-related manner.
3) When TRH at a dose of 1 ng/ml, 10 ng/ml or 100 ng/ml was perifused for 120 min at a rate of 0.4 ml/min, a large amount of PRL was released during the early period of the TRH infusion, and then the PRL release gradually decreased to the basal levels in spite of the continuous TRH infusion. An additional TRH, of which the concentration was ten-fold higher than the TRH level in the continuous infusion, when added at the end of the continuous TRH infusion, had no effect on PRL release. On the other hand, a 5 minute TRH infusion given at 30 min after the end of the continuous TRH infusion caused a significant increase in PRL release.
4) A continuous perifusion with 1 mM 8-bromo-cyclic AMP caused a small but continuous PRL release. An additional continuous 8-bromo-cyclic AMP infusion during the late period of a continuous TRH infusion caused a continuous PRL release similar to that induced by the continuous infusion of cyclic AMP only.
5) A short period perifusion with 1×10^-9 NI to 1× 10^-7M of vasoactive intestinal polypeptide (VIP) enhanced a significant increase of PRL release in a dose-related manner, but the amounts of PRL release induced by VIP were smaller than those induced by TRH.
6) A continuous VIP infusion elicited a significant continuous PRL release. An additional continuous VIP infusion during the late period of a TRH infusion caused a similar PRL response similar to that induced by the continuous infusion of VIP only. An additional TRH infusion during the continuous VIP infusion caused a large amount of PRL release similar to that induced by the continuous infusion of TRH only. These results indicate that TRH action on mammatrophs is rapidly blunted by an unknown mechanism, and the desensitization of TRH-induced PRL release is easily recovered by the cessation of TRH infusion. The mechanism by which TRH releases PRL using rat pituitary cells may be different from that of VIP-induced PRL release. The PRL release induced by VIP may be due to cyclic AMP.

View full abstract

The effects of corticosterone (CS) on the gonadotropin surge induced by estradiolbenzoate (E₂) were studied in adrenalectomized and ovariectomized (ADRX-OVEX) rats. The results are as follows.
1) In ADRX-OVEX rats implanted with E₂-tablets in the bilateral axillae, LH and FSH surges occurred 4 days after the implantation of E₂, peaking at 17 : 00 h. The levels of these surges were markedly higher than those in OVEX rats similarly treated but were attenuated significantly by the subcutaneous injection of CS (25 μg in sesame oil) given at 12 : 00 h.
2) The CS implantation (0.5 μg in 2 μl sesame oil) into the dorsal hippocampus at 15 : 00 h significantly inhibited the levels of LH and FSH surges in ADRX-OVEX rats with E₂-tablets. The effect of the CS implant in the lateral septal nucleus was also inhibitory but not statistically significant. The CS administration in the ventral part of the midbrain tegmentum did not elicit any change in the surge of LH and FSH.
3) In animals with the dorsal fornix-section at the post-anterior-commissural level, surges of LH and FSH also occurred in the afternoon of the 4th day after the E₂-tablets implantation, but the levels of LH and FSH were not significantly altered by an intravenous injection of CS (5 μg in saline) at 15 : 30 h.
It was suggested the CS circulating in the blood would induce a rise of hippocampal activity which would exert a suppressive influence on the gonadotropin release.

View full abstract