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Biomedical subjects

K Suemaru

Publications and source records attributed to K Suemaru.

30 records · Page 2Linked to original sources
PubMed1993

Effect of beta-adrenergic receptor antagonists on nicotine-induced tail-tremor in rats.

The effects of various beta-adrenergic receptor antagonists on nicotine-induced tail-tremor were investigated in rats. Atenolol (5 and 10 mg/kg, IP), arotinolol (5 and 10 mg/kg, IP), and carteolol (5 and 10 mg/kg, IP), hydrophilic beta-adrenergic receptor antagonists, did not affect the tail-tremor induced by nicotine given at a dose of 0.5 mg/kg SC. However, propranolol (5-20 mg/kg, IP) and pindolol (5-20 mg/kg, IP), nonselective and lipophilic beta-adrenergic receptor antagonists, did suppress the tail-tremor dose dependently. In contrast, metoprolol (5-20 mg/kg, IP), lipophilic and beta 1-selective adrenergic receptor antagonists, did not show such an effect. These results suggest that nicotine-induced tail-tremors may be mediated through central beta 2-adrenergic receptors as an appearance and developmental mechanism.

Adrenergic beta-1 Receptor Antagonists↗
PubMed1993

Chronic nicotine treatment potentiates behavioral responses to dopaminergic drugs in rats.

In the present study, the behavioral effects of apomorphine, methamphetamine, and haloperidol were examined in nicotine-treated rats. All animals were SC administered nicotine at a dose of 0.5 mg/kg or saline once daily for 14 days. Hyperlocomotion induced by apomorphine (0.2 mg/kg, IP) and methamphetamine (1.0 mg/kg, IP) was greater in nicotine-treated rats than in control rats. Stereotyped behaviors induced by apomorphine (1.0 mg/kg, IP) and methamphetamine (5.0 mg/kg, IP) were also potentiated in nicotine-treated rats. However, the incidence of catalepsy induced by haloperidol (0.25-1.5 mg/kg, IP) was slightly lower in nicotine-treated rats. These results suggest that chronic nicotine treatment may increase the susceptibility of the dopaminergic system to dopaminergic drugs.

Animals↗
PubMed1993

[Cerebrospinal fluid and plasma corticotropin-releasing hormone (CRH) in dentatorubropallidoluysian atrophy (DRPLA)--study in two cases of hereditary DRPLA].

The levels of corticotropin-releasing hormone (CRH) in cerebrospinal fluid (CSF) and plasma were examined in two cases of hereditary dentatorubropallidoluysian atrophy (DRPLA). Both patients were female and showed cerebellar ataxia, choreic movement and subcortical dementia. The onset ages of the first and second patients were 30 and 47 years, respectively. The first patient did not have the cerebral white matter damage (CWD). The second patient of late onset was associated with marked and diffuse CWD which was shown as high signal intensity by T2-weighted image on MRI. Regardless of accompaniment with CWD, the radioimmunoassay studies of CSF and plasma CRH revealed that both patients had markedly reduced levels of CRH in CSF and plasma. Together with the recent anatomic evidence on the distribution of CRH neurons and receptors in the central nervous system, the present results suggest that degeneration of the subcortical structures including the basal nuclei, the brain stem and the cerebellum involves degeneration and/or dysfunction of the CRH neuronal system which, presumably, are related to those of some other neurotransmitter systems, and that the reduced activity of the CRH system plays a pathophysiological role in such diseases as DRPLA with degeneration of the subcortical nuclei and the cerebellum.

Adult↗
PubMed1992

Effect of long-term cigarette smoke exposure on locomotor activity and brain monoamine levels in rats.

Rats were chronically exposed to cigarette smoke for 20 min twice daily using a smoking machine. On days 1, 4, and 14, locomotor activity and rearing were measured for 15 min in an open-field apparatus. On day 1, exposure to cigarette smoke increased locomotor activity and rearing in the latter half of the observation period. This effect became more pronounced on days 4 and 14. Chronic cigarette smoke exposures for 21 days significantly decreased the norepinephrine levels in the hypothalamus, thalamus, and pons-medulla, but not the levels of dopamine, 5-hydroxytryptamine, or their metabolites. These results suggest that repeated cigarette smoke exposure increasingly stimulates locomotor activity and rearing and affects norepinephrine metabolism, especially in the brainstem.

Animals↗
PubMed1991

Cerebrospinal fluid and plasma corticotropin-releasing hormone in senile dementia.

Cerebrospinal fluid (CSF) levels of corticotropin-releasing hormone (CRH) and ACTH, and plasma levels of CRH, ACTH and cortisol were determined in samples taken simultaneously from 28 patients with dementia including senile dementia of the Alzheimer type (SDAT), multi-infarct dementia (MID), dementia following a cerebrovascular accident (CVD), and the borderline-to-normal state. CRH levels in CSF were significantly reduced in patients with SDAT and CVD, but not in those with MID, as compared with the borderline cases. ACTH levels in CSF were significantly reduced in the patients with SDAT compared to those with MID. Reduced CRH levels in CSF were found in the patients who showed severe dementia and poor activities of daily living (ADL). Plasma levels of CRH, ACTH and cortisol were normal and were not significantly different among the four groups of patients. CRH levels in CSF were positively correlated with ACTH levels in CSF, but not with the levels of plasma CRH, ACTH or cortisol. Plasma CRH levels were positively correlated with plasma ACTH levels. These results suggest that: 1) abnormalities in the extrahypothalamic CRH system play a role in the pathophysiology of senile dementia, which may not be specific to SDAT; 2) CSF CRH is correlated with the severity of dementia and ADL; 3) the levels of CRH in CSF and plasma are independent, and 4) the plasma CRH reflects, at least in part, the activity of the hypothalamic CRH regulating the secretion of pituitary ACTH.

Adrenocorticotropic Hormone↗
PubMed1991

Tail-tremor induced by exposure to cigarette smoke in rats.

Tremors appearing only in the tail (tail-tremor) induced by cigarette smoke and subcutaneous nicotine were investigated using a smoking machine and Wistar rats. Daily exposure (twice a day) to smokes of two commercial cigarettes (Mild-Seven Select for the first 7 days and Long-Peace for the next 6 days) caused the tail-tremor to appear even if it was slight. A single subcutaneous nicotine (0.5 mg/kg) administration to rats exposed to the cigarette smokes for 13 days markedly caused the tail-tremor. On the other hand, daily subcutaneous injection of nicotine (0.5 mg/kg/day) also caused the tail-tremor to appear beginning on the 4th day and the incidence of tremor increased to 100% by the 12th day. These results indicate that tail-tremor can be caused not only by daily subcutaneous administration of nicotine but also by daily exposure to cigarette smoke.

Animals↗
PubMed1991

Hyperkinesia, plasma corticotropin releasing hormone and ACTH in senile dementia.

Senile dementia of the Alzheimer type (SDAT), in contrast to multi-infarct dementia (MID) was associated with delirium and marked increases in the number of walking steps taken during both the day and night. In SDAT patients, plasma ACTH levels in the afternoon and evening were higher but plasma corticotropin releasing hormone (CRH) levels in the evening were lower than in the MID patients. A positive correlation between ACTH levels and walking steps and a negative correlation between plasma levels of CRH and ACTH were found. These results suggest relevance of hyper-kinetic delirium to disruption of diurnal rhythm of the pituitary-adrenal axis, and a possible mechanism of the short feedback suppression of CRH release by increased circulating ACTH.

Adrenocorticotropic Hormone↗
PubMed1991

Effect of cigarette smoking on theophylline pharmacokinetics in rats.

The effect of acute cigarette smoke inhalation on the plasma levels of theophylline administered orally and parenterally to rats has been studied. The animals were exposed to smoke containing low- or high-nicotine/tar concentration for 10 min immediately after oral, intraperitoneal (i.p.) or intravenous (i.v.) administration of theophylline. The plasma levels of theophylline when administered orally (20 mg kg-1) were lower in the two cigarette smoke-inhaling groups than in the non-smoking restrained control group, with the lowest values in the high-nicotine/tar group. The plasma levels (8 and 12 h after administration) in the high-nicotine/tar group when theophylline was administered i.p. (10 mg kg-1), were also slightly lower than in the non-smoking restrained control group but this was not significant. When theophylline was administered i.v. (5 mg kg-1), there was no difference between the high-nicotine/tar group and the non-smoking restrained control group. These data indicate that cigarette smoke inhalation causes suppression or delay of theophylline absorption from the gastrointestinal tract.

Administration, Oral↗
PubMed1990

Behavioral effects of HR-592, a new derivative of indole.

Effects of HR-592 on various behaviors were investigated in rats and mice. 1) HR-592 at doses of 10-100 mg/kg, p.o., and chlorpromazine at doses of 2.5-20 mg/kg, p.o., suppressed dose-dependently spontaneous activities of mice. 2) In the mice treated with HR-592, 10 and 30 mg/kg, p.o., and with chlorpromazine, 1.25-5 mg/kg, p.o., the durations of loss of the righting reflex induced by thiopental-Na were extended in a dose-dependent manner. 3) In the mice and rats when HR-592 was administered at doses of 3-100 mg/kg, p.o., catalepsy was induced in a dose-dependent manner. 4) The incidence of catalepsy induced by haloperidol in mice was reduced dose-dependently after HR-592 administration (10-100 mg/kg, p.o.). 5) Dose-dependent suppressions of the slant of screen at which the mice slipped down were observed by HR-592 at 3-100 mg/kg, p.o., and chlorpromazine at 5-20 mg/kg, p.o. 6) The rotarod performance in mice was suppressed dose-dependently by HR-592, 3-100 mg/kg, p.o., and chlorpromazine, 5-20 mg/kg, p.o. 7) HR-592 at doses of 0.3-3 mg/kg, i.p., suppressed dose-dependently the turning behavior induced by methamphetamine in unilateral substantia nigra-lesioned rats. From these results and our previous data, it is considered that HR-592 has pharmacological properties as a major tranquilizer, although its behavioral effect is slightly weaker than that of chlorpromazine. Furthermore, these results imply that HR-592 has anti-cataleptogenic activity and might thereby alleviate the adverse effect of neuroleptics such as haloperidol.

Anesthetics↗
PubMed1989

Nicotine-induced tail-tremor and drug effects.

Tail-tremor induced by repeated and daily administration (0.5 mg/kg SC x 6 times/day) of nicotine as well as effects of various drugs on this response were investigated in Wistar strain male rats. Daily administration of nicotine in doses of 0.5 mg/kg SC caused tail-tremors to appear beginning on the 3rd day. Tail-tremor induced by the first injection of each day gradually increased with the daily injections, however, the heightened effect of this first injection at the beginning of each day decreased during the day upon repeated administration of 6 times/day at 2-hr intervals. Basically, tail-tremor appeared about 5 min after SC administration of nicotine and reached a peak approximately 7-9 min after injection, declining to zero afterwards. Different drugs showed various effects on this response. While mecamylamine (0.5 and 1.0 mg/kg IP) abolished nicotine-induced tail-tremor, arecoline (0.5 and 1.0 mg/kg IP), atropine (2.5 and 5.0 mg/kg IP), scopolamine (1.0 and 2.0 mg/kg IP) and hexamethonium (0.5 and 1.0 mg/kg IP) showed no such effects. Furthermore, physostigmine (0.1 mg/kg IP) actually potentiated this action. These results suggest that tail-tremor induced by nicotine may be mediated through central nicotine receptor system.

Animals↗