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Biomedical subjects

S Amir

Publications and source records attributed to S Amir.

At least 127 records · Page 7Linked to original sources
PubMed1982

Involvement of endogenous opioids with forced swimming-induced immobility in mice.

The present study investigated the involvement of endogenous opioid mechanisms with the immobility response induced in mice by forced swimming. Pretreatment with the narcotic antagonist naloxone (0.625--40.0 mg/kg) caused a dose-dependent decrease in the duration of immobility in mice subjected to a 10 min swim test. This effect was more pronounced in C57BL/6J mice than in BALB/C mice. A low dose of morphine (0.15 mg/kg) potentiated immobility whereas higher doses (0.625/10.0 mg/kg) had no demonstrable effect on immobility in these strains. The results suggest that release of endogenous opioids may be a physiological event promoting natural cataleptic-like behaviors in mice.

Animals↗
PubMed1982

Endogenous opioids interact in stress-induced hyperglycemia in mice.

Intermittent inescapable foot shock stress for 1 hour elicited significant hyperglycemia in mice. Pretreatment with the long acting narcotic antagonist naltrexone (1.0 mg/kg, 1 hr prior to stress) prevented stress hyperglycemia. Naltrexone did not affect blood glucose in unstressed control mice. These findings suggest the involvement of endogenous opioids in the hyperglycemic response to stress in mice. The possible mode of interaction of endorphin in stress hyperglycemia is discussed.

Animals↗
PubMed1981

Pinch-induced catalepsy in mice.

Pinch-induced catalepsy was readily obtained in five strains of mice following repeated administration of strong pinches at the scruff of the neck. This catalepsy outlasted the pinch by minutes and was more easily induced on retests 48 hr after the initial acquisition tests. Repetitive tail pinches and/or exposure to the testing procedure without pinches also resulted in immobility; however, this was weak in magnitude and short in duration. Treatments designed to prevent immobility between trials (swimming in water or housing in the home cage with normally behaving littermates) failed to block or modify pinch-induced catalepsy. Spacing the trials up to one pinch per 10 min did not affect the emergence of pinch-induced catalepsy, but at one pinch per 30 min it was abolished. Pinch-induced catalepsy is strikingly similar to the behavior elicited in mice when attacked by a cat. In both cases, immobility is produced by pinches or bites at the scruff of the neck, and it outlasts the duration of the stimulus. These results support the notion of pinch-induced catalepsy as an adaptive coping strategy, increasing the chance of survival in predator/prey confrontations.

Animals↗
PubMed1980

Opiate receptors may mediate the suppressive but not the excitatory action of ACTH on motor activity in rats.

Subcutaneous injections of adrenocorticotropin (ACTH) or of the opiate antagonist naltrexone produced a one (2.0 mg/kg) dpressed, whereas smaller doses of ACTH (50 micrograms/kg) and of naltrexone (0.125 and 0.25 mg/kg) stimulated motor activity in the open field test. Furthermore, naltrexone at a dose level that had no effect on motor activity blocked the suppressive effect of the high doses of ACTH but had no effect on the stimulating effect of the intermediate dose of ACTH. Finally, chronic naltrexone administration resulted in enhanced sensitivity to the suppressive but not to the stimulating effect of ACTH on motor activity. It is argued that opiate receptors may play a selective role in the effect of ACTH on motor activity. Such receptors may mediate the supressive effect of high doses of ACTH whereas other, naltrexone insensitive receptor systems may mediate the stimulating effect of ACTH on activity functions.

Adrenocorticotropic Hormone↗
PubMed1980

The role of endorphins in stress: evidence and speculations.

Several lines of evidence suggest that the endogenous opioid peptides endorphins may play a role in the defensive response of the organism to stress. The present paper summarizes these findings as well as evidence linking endorphins to the anterior pituitary polypeptide hormone adrenocorticotropin (ACTH). Evidence is presented that endorphins may function as trophic hormones in peripheral target organs such as the adrenal medulla and the pancreas. As such they may be part of the physiological mechanisms that mediate adrenaline and glucagon release in response to stress. Endorphins (enkephalins) are also suggested to play a role in the control of the pituitary gland during stress. In such capacity they may act as hormone-releasing or inhibiting factors. Finally, endorphins appear to play a role in the behavioral concomitants of stress. In such capacity endorphins are suggested to function as modulators of neural systems that mediate the elaboration and expression of the reactive/affective components of stress. Speculations on the mode of interaction between endorphins and ACTH in the global response to stress are discussed.

Adaptation, Physiological↗
PubMed1979

Enhanced analgesic effects of stress following chronic administration of naltrexone in rats.

Chronic administration of the long acting opiate antagonist naltrexone potentiated the analgesic effects of foot-shock stress in the hot-plate test in rats. No changes in pain responsiveness were noted in naltrexone-treated rats that were not subjected to the foot-shock treatment. The results suggest that chronic opiate receptor may lead to the development of supersensitivity in endogenous opiate systems that mediate the analgesic effects of stress.

Analgesia↗
PubMed1979

The protective influence of progestogen only contraception against vaginal moniliasis.

The incidence of Candida albicans (C.A.) infection of the vagina was evaluated in vaginal discharges obtained from 85 subjects using a large battery of culture media and confirmatory tests. Twenty women using DMPA 150 mg i.m. contraceptive injections for more than one year (long-term users) were compared with forty 2nd trimester pregnant cases with respect to vaginal candidiasis. The basis of comparison was the presence of amenorrhea and high hormonal levels in both groups. However, pregnant subjects showed a 60% prevalence while none of the DMPA cases had a positive culture or smear. Another group of 25 cases was similarly studied once before DMPA injection and again three months following drug administration (short-term use). The pre-therapy samples demonstrated a 32% incidence which was reduced to 8% after three months of use. It therefore appears that progestogen only contraceptives have the advantage of some protective influence against monilial vaginitis. Moreover, the use of these drugs may carry the beneficial potential of use in resistant cases of monilial vaginitis, either as a single approach or better as a supplementary procedure to known antifungal agents.

Adult↗