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Biomedical subjects

R Hashimoto

Publications and source records attributed to R Hashimoto.

At least 145 records · Page 8Linked to original sources
PubMed1988

Preoptic injection of VIP, but not of secretin or PHI, inhibits LH and stimulates prolactin secretion in the ovariectomized rat.

The microinjection of vasoactive intestinal peptide (VIP) into the medial preoptic area rapidly inhibited pulsatile luteinizing hormone (LH) secretion within 1 h in ovariectomized rats. A transient but significant increase in prolactin (PRL) secretion occurred after VIP injection coincidentally with the initiation of the inhibition of LH pulses. Preoptic microinjections of secretin or peptide histidine isoleucine amide (PHI) did not have such effects. These results suggest specific actions of VIP, despite its structural similarity to secretin and PHI, on the preoptic mechanisms governing LH and PRL secretion in ovariectomized rats.

Animals↗
PubMed1988

Effects of preoptic injection of glucagon on luteinizing hormone secretion in ovariectomized rats with or without estrogen priming.

Effects of microinjection of glucagon or GIP into the medial preoptic area on luteinizing hormone (LH) and prolactin (PRL) release were examined in unanesthetized ovariectomized rats with or without estrogen priming. Microinjection of glucagon (1.0 microgram) into the medial preoptic area of ovariectomized estrogen-primed rats significantly facilitated the circadian afternoon rise in LH secretion as compared to the hormone values in control animals microinjected with physiological saline. The timing of the afternoon LH rise was not altered by glucagon and the circadian rise of PRL secretion was not altered by glucagon injected in the preoptic area. The injection of GIP did not have any significant effect on either LH or PRL secretion. In ovariectomized estrogen-unprimed rats, on the other hand, glucagon did not affect the pulsatile LH secretion, but it inhibited PRL secretion. GIP did not affect any hormone secretion. The results show that (1) glucagon, as other secretion family peptides such as secretion and PHI, can stimulate the preoptic LH secretory mechanism that undergoes the circadian clock mechanism under the influence of estrogen, and (2) without estrogen priming, glucagon in the preoptic area inhibits PRL secretion.

Animals↗
PubMed1988

Plasma biopterin levels of patients with affective disorders.

The plasma biopterin levels of 13 patients with affective disorders were measured both in the symptomatic phase and in the remission phase, and under no influence of psychotropic drugs except lithium and/or carbamazepine by high-performance liquid chromatography with fluorescence detection, and were compared with those of normal controls. The biopterin levels of patients in the symptomatic phase were elevated significantly as compared with those of normal controls, and the elevation tended to be more pronounced in the hypomanic phase than in the depressive phase. In contrast, the biopterin levels of patients in remission were not different from those of normal controls.

Adult↗
PubMed1988

Quadricuspid aortic valve perforation resulting from bacterial endocarditis--2-D echo- and angiographic diagnosis and its surgical treatment.

A 75-year-old man with quadricuspid aortic valve regurgitation affected by bacterial endocarditis is reported. The aortic valve consisted of 4 equal-sized cusps (type a) and a supernumerary cusp located between the right and noncoronary cusps. A right coronary ostium was close to the accessory commissure, but there was no displacement. A few small fenestrations were found at the 4 commissures and a large perforation resulting from endocarditis was observed in the noncoronary cusp. 2-D echocardiogram and angiogram suggested these findings, and they were confirmed at surgery. Successful aortic valve replacement was achieved.

Aged↗
PubMed1987

The depressor effect of secretin administered either centrally or peripherally in conscious rats.

The role of secretin in systemic blood pressure was examined in conscious rats. Either i.c.v. (0.5 or 1.0 micrograms/2 microliter 0.9% saline) or i.v. (1.0 or 2.0 micrograms/10 or 25 microliter saline) administration of secretin in conscious rats resulted in a significant fall in blood pressure. In consideration of previous findings that many other peptides such as substance P, enkephalin, bradykinin, neurotensin and vasoactive intestinal polypeptide cause pressor effects when administered centrally, but produce depressor responses after peripheral administration, the hypotension induced as both central and peripheral effects of secretin is unique and significant.

Animals↗
PubMed1987

Total biopterin levels of plasma in patients with depression.

The total biopterin levels of plasma in 12 patients with depression were measured. They were elevated significantly as compared with those in normal controls. The plasma biopterin levels in 6 of 12 patients were measured both in the depressive and in the remissive phases. In the depressive phase the total biopterin levels were increased, whereas in the remission phase they did not differ from those in normal controls. Antidepressants did not affect the plasma biopterin levels. We speculate that the elevation of the plasma biopterin levels in patients with depression was related to the depressive state itself.

Adult↗
PubMed1987

Roles of catecholamine at the preoptic region in the regulation of cyclic ovulation and gonadotropin.

Experiments were designed to see how a transplantation of newborn norepinephrine (NE) neurons from A-6 groups or dopamine (DA) neurons from A-10 groups in the third ventricle at the level of the preoptic region affected the vaginal oestrous cycle and gonadotropin secretion in the female rat. Sixty-two rats that had tissues in contact with the preoptic region were evaluated as having surviving transplants by histological examination after sacrifice. The rats that had surviving NE-neuron transplants frequently showed prolongation of oestrus during the 70-day study period, indicating that ovulation was severely impaired in these rats. However, after ovariectomy, they showed a pulsatile secretion of LH with a remarkably large amplitude. The DA-neuron transplants sustained the oestrous cycle unchanged, but increased blood levels of FSH prior to the ovulatory secretion of gonadotropin. Pulsatile LH secretion was not affected. Sham and cerebellum control rats did not show any significant changes in the oestrous cycle. The results suggest that the NE-neuron transplants at the preoptic region somehow inhibit gonadotropin secretion in intact rats, whereas they facilitate it in ovariectomized rats. The DA-neuron transplants appear to exert facilitatory effects on FSH secretion in intact rats.

Animals↗