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Biomedical subjects

S Yehuda

Publications and source records attributed to S Yehuda.

At least 91 records · Page 5Linked to original sources
PubMed1979

A possible link between intelligence level and habituation of the GSR.

An attempt was made to correlate the intelligence level of three well-defined groups (Gifted, IQ 140; Normal, 95 IQ 105: Mentally retarded, 45 IQ 55) and the habituation rate and pattern of a GSR response to a series of light stimuli. The results indicate that the gifted and normal groups yield systematic patterns of GSR responding in contrast to the mentally retarded, whose distribution of GSR response pattern differs. The mentally retarded seem to yeild a larger number of ill-defined, non-systematic GSR responses. These results indicate a possible link between the measured level of intelligence by IQ test and the habituation pattern in an autonomic nervous system response.

Adolescent↗
PubMed1978

Effects of d-amphetamine on the set point of the thermoregulatory system in rats.

Exposing a rat's tail to an ambient temperature lower than that sensed by the rest of the body causes an increase in body temperature. Pretreatment with d-amphetamine causes an even greater increase in body temperature. Morover, while control rats perceive any ambient temperature below 20 degrees C as 'cold', amphetamine-treated animals only perceive ambient temperatures below 20 degrees C as 'cold'. This effect of d-amphetamine was found not only when the body temperature of the rats was 20 degrees C, but also when the body was kept at ambient temperatures of 15 degrees--4 degrees C. Because this effect of d-amphetamine, i.e., shifting of the reference point among treated rats, was found in two other situations (behavioral thermoregulation and in studying the anorexic effects of d-amphetamine among rats kept at different ambient temperatures), the best explanation is that in addition to the effects of the drug upon some thermal sensory roles, it also causes a change in the value of the set point of the thermoregulatory system, and drug-treated rats perceive ambient temperatures of 10 degrees C as 'normal'.

Animals↗
PubMed1977

The possible role of dopamine in phenothiazine-induced hypothermia in rats: an application to DA hypothesis of schizophrenia.

Hypothermic effects of d-Amphetamine, chlorpromazine, a variety of other phenothiazines, ET495 and haloperidol in rats at 4 degrees C were measured separately and in combination. All the drugs produced some hypothermia. Among the phenothiazines, degree of hypothermia induced was found to be correlated with relative effectiveness of the drug as an antipsychotic agent. Hypothermic effects of each of the phenothiazines in combination with d-Amphetadrugs as an antipsychotic agent. Hypothermic effects of each of the phenothiazines in combination with d-Amphetamine was greater than for either drug alone. Hypothermic effects of the combination CPZ with Amphetamine was potentiated by haloperidol but blocked by ET495. The evidence supports a model of neuronal feedback loops either within the central DA mesolimbic pathway or between the mesolimbic and nigrostriatal DA systems. The establishment of interdependency between antipsychotic and hypothermic effects of phenothiazines offers promise not only to a greater understanding of the mechanisms underlying these effects, but the possibility of an objective test for screening new materials for antipsychotic effectiveness.

Animals↗
PubMed1977

D-Amphetamine thermal effects, metabolic rate and motor activity in rats.

The effect of d-amphetamine-induced hypothermia among rats maintained at a cold ambient temperature is related to its ability to release dopamine in the dopaminergic neurons in the mesolimbic pathway. However, the physiological mechanisms which mediate the hypothermia (heat loss or a decrease in heat production) are not known. Since we have failed to demonstrate effects induced by d-amphetamine on food intake or on heat sensors on the rat's tail we conclude that these are not the mechanisms involved in hypothermia. Effects of d-amphetamine on O2 consumption and CO2 production of rats kept at various ambient temperatures were investigated in order to find out if there is any relation between a decrease in body temperature and a decrease in the Basal Metabolic Rate. Neither such relations nor any relations between levels of body temperatures and levels of motor activity were found. The problem of the peripheral mechanisms involved in d-amphetamine-induced hypothermia remain as yet unidentified.

Animals↗
PubMed1977

The effects of d-amphetamine and temperature on p-cresol and pentylenetetrazol induced convulsions.

Each of twelve (12) rats were subjected to temperatures of 37c, 20c, and 4c in an environmental chamber. Seizure responses to p-cresol injections produced a U-shaped function, with minimal seizures occuring at 20c. Subsequent administration of d-amphetamine eliminated seizures, except at 4c, at which temperature only stereotyped behavior was observed. Environmental temperature effects on metrazol injections in a second group (N=72) seemed to increase linearly with respect to seizure susceptibility and mortality, although latency to first seizure was also a U-shaped function. The findings are discussed in the context of developing a model of epilepsy appropriate for behavioral research.

Animals↗
PubMed1976

Interaction effects of d-amphetamine treatment and ambient temperature on rat's food intake.

The "thermoregulatory theory of hunger" posits that rats placed in a cold environment should increase the amount of food intake, while rats placed in a hot environment should decrease their food intake. d-Amphetamine causes hyperthermia among rats kept at warm ambient temperature, and results in hypothermia among animals kept in a cold environment. d-Amphetamine-caused-hyperthermia should therefore result in decreased eating behavior, and d-amphetamine-caused hypothermia should result in increased eating behavior. One must take into account the fact that d-amphetamine is an anorexic drug. The interaction between (a) ambient temperature, (b) body temperature and (c) food intake were tested on groups of rats injected with various doses of d-amphetamine (1.5-15 mg/kg) and placed in ambient temperatures ranging from 4-37 degrees C. No increase in food intake was revealed under any dosage or temperature condition. The decrease in food intake found with d-amphetamine treated animals could not be explained in the "thermoregulatory theory of hunger". Our data indicate that d-amphetamine anorexic effects and thermal effects are mediated by different mechanisms.

Animals↗
PubMed1976

Effects of specific brain lesions on the thermal responses of rats to D-amphetamine.

Lesions in either olfactory bulb or in area postrema modify the amphetamine-induced paradoxical thermoregulatory behavior, although these lesions in no way affect amphetamine-induced hypothermia. In addition, these lesions lead to complicated patterns of thermoregulatory behavior. These results can be best explained by assuming that lesions in one part of the brain monoamine system might affect levels and turnover of monoamines in remote parts of the brain. Among d-amphetamine behavioral effects which are known to be mediated by central dopaminergic neurons are hypothermia in animals placed in a cold environment, and paradoxical thermoregulatory behavior (this involves the movement of animals away from the heating source despite hypothermia). This latter effect requires intact alpha norepinephrine receptors. It seems that neither type of lesion affected dopaminergic neuronal activity in the brain. However, norepinephrine activity in the brain was affected by the area postrema lesion as well as by the olfactory bulb removal.

Animals↗
PubMed1975

Dopaminergic neurons in the nigro-striatal and mesolimbic pathways: mediation of specific effects of D-amphetamine.

The administration of d-amphetamine (15 mg/kg, i.p.) to rats causes stereotypy, hypothermia among animals placed in a cold environment, and paradoxical behavioral thermoregulation (i.e., animals in a cold environment choose not to place themselves under the beam emitted by a heat lamp). These effects are blocked in animals lesioned unilaterally in the mesolimbic dopaminergic projections to the olfactory tubercule and nucleus accumbens. In contrast, a unilateral lesion destroying the nigro-striatal projections within the caudate nucleus blocks none of these responses, and actually potentiates the induction of stereotypy by d-amphetamine. Both lesions cause the animal to exhibit rotational behavior in response to the subsequent administration of d-amphetamine. These observations suggest that the mesolimbic dopaminergic projections mediate some of the behavioral and visceral effects of d-amphetamine.

Animals↗