PubMed Health⌕ Search

Biomedical subjects

S Yehuda

Publications and source records attributed to S Yehuda.

At least 19 recordsLinked to original sources
PubMed1995

Modification of cytokine secretion following mild emotional stimuli.

In the present study, changes in the cytokine system (IL-1 beta, IL-2, IL-3, IL-6 and TNF alpha) were assessed following exposure to mild mood induction (negative and positive) in humans. An increase in secretion of TNF alpha, a decrease in that of IL-2 and of IL-3 with no change in IL-1 beta and in IL-6 secretion levels, was observed in response to mild negative emotional changes. A reversed cytokine secretion profile was found following positive mood changes, suggesting the hypothalamic-pituitary-adrenal axis and the autonomic nervous system, as possible mediators underlying these effects, specific to the nature of the emotion.

Adolescent↗
PubMed1995

Essential fatty acid preparation (SR-3) rehabilitates learning deficits induced by AF64A and 5,7-DHT.

The purpose of this study was to examine the possible effects of a novel mixture of fatty acids, SR-3 (a specific ratio between alpha-linolenic and linoleic acids) on learning deficits induced by cholinergic (AF64A) and serotonergic (5,7-DHT) neurotoxins in rats. I.c.v. AF64A and 4th ventricle administration of 5,7-DHT induce severe learning deficit using the Morris Water Tank. Three weeks of treatment with SR-3 rehabilitated the learning capacity of rats. However, learning deficits induced by a lesion in area postrema was not rehabilitated by SR-3. The mode of action of SR-3 is unknown. We propose that this combination of free fatty acids modulates the composition of neuronal membrane lipids and allows better neuronal communication.

Animals↗
PubMed1994

Essential fatty acid preparation (SR-3) raises the seizure threshold in rats.

The anticonvulsant properties of a mixture of non-esterified alpha-linolenic acid and linoleic acid with a ratio of 1:4 (SR-3) were evaluated in four rat models of epileptic seizures: (1) i.p. injection of a single convulsant dose (50 mg/kg or 100 mg/kg) of pentylenetetrazol; (2) repeated subconvulsant doses of pentylenetetrazol; (3) cortical irritation by intraventricular administration of iron chloride (FeCl3); and (4) audiogenic seizure-prone preparation created by repeated pretreatment with p-cresol. Treatment with SR-3 (about 40 mg/kg i.p.) for a period of 3 weeks prior to challenge was found effective in each of these experimental models and caused up to a 22-fold increase in latency to major motor seizures, up to 84% reduction in the number of rats with seizures, and up to a 97% reduction in the duration of seizures. It is postulated that the anticonvulsant effects of SR-3 may be related to its stabilization of neuronal membranes. SR-3 should be evaluated further as a treatment for epilepsy.

Acoustic Stimulation↗
PubMed1994

Decrease of serum iron in acutely psychotic schizophrenic patients.

Iron deficiency has been shown to effect the dopaminergic system. Iron deficient rats have low dopamine D2 receptor levels and modified dopamine-mediated behaviors, including reversal of circadian cycles of these behaviors. Abnormal iron deposits have been found in the brains of schizophrenics in CT and post mortum studies. We examined serum iron levels at 0800, 1700 and 2400 hours in 26 medication free schizophrenic patients in acute psychotic relapse and compared them to iron levels in a normal control group. The results show significant decreases in the iron levels at 1700 and 2400, and a non significant drop in the 0800 levels. A feedback mechanism involving iron and dopamine is proposed.

Acute Disease↗
PubMed1993

Modulation of learning, pain thresholds, and thermoregulation in the rat by preparations of free purified alpha-linolenic and linoleic acids: determination of the optimal omega 3-to-omega 6 ratio.

Ingested polyunsaturated fatty acids are postulated to lead to changes in central nervous system activity, presumably by altering the lipid composition of neuronal membranes. In support of this hypothesis, we and other investigators have previously demonstrated cognitive effects in rats fed oils that contain both alpha-linolenic acid (18:3 omega 3) and linoleic acid (18:2 omega 6), with the relative content of alpha-linolenic acid being seen as the critical variable. The present study in rats examined the effects of preparations containing different ratios of highly purified free alpha-linolenic acid to linoleic acid (about 25 mg/kg of body weight daily) on learning performance (Morris water tank), pain thresholds (heated plate), and thermoregulatory control of d-amphetamine-induced hypothermia during 4 weeks of treatment. Preparations with omega 3-to-omega 6 ratios ranging from 1:3.5 to 1:5 (specifically a ratio of 1:4) produced significant favorable effects on all of these variables. Although the specific mode of action remains to be elucidated, these results suggest that such preparations of free fatty acids should be evaluated in the treatment of memory disorders and pain conditions.

Animals↗
PubMed1991

The effect of pain on pentylenetetrazol induced seizures.

Repeated administrations of subconvulsive doses of pentylenetetrazol (PTZ) leads to frank convulsions. The number of injections required to bring about such an effect is taken as an index of seizure vulnerability, and was studied in normal rats. This study examined the effect of pain induced by formaline injection or placement on a hot plate on seizure elicitation. The results could be accounted for by the role of arousal and/or endogenous opiates that are generated by the pain induction procedures, wherein the pain appears to provide some elevation of the threshold for seizure vulnerability.

Animals↗
PubMed1991

The effects of iron deficiency and electric shock on learning in rats.

It is hypothesized that electric shock can compensate for the learning deficit caused by iron deficiency in the experimental rat population, and that this effect will be sustained over a 3-week "rehabilitation" period. Forty-seven female Sprague-Dawley rats served as the experimental subjects. The learning capacity of the rats was assessed using a water Y-maze. The dependent variables were assessed twice, once after half had been made iron deficient, and again after the iron deficiency had been corrected. A 2 x 2 x 2 analysis of variance with repeated measures was employed, along with post-hoc tests, to assess the effects of the experimental manipulations on the rats' performance. The experimental results replicated previous findings regarding the damaging effects of iron deficiency on learning capacity in rats and confirmed that shock improves the performance of rats in the water Y-maze. Furthermore, it was found that shock and iron deficiency interact, such that the performance of iron-deficient rats subjected to electric shock is superior to that of rats not made iron deficient. This trend persists even after the hematological effects of iron deficiency are corrected, although to a less dramatic degree. A possible explanation for these findings is advanced.

Animals↗
PubMed1989

Putative biological mechanisms of the effect of iron deficiency on brain biochemistry and behavior.

An animal model of nutritional iron deficiency (ID) is described that demonstrates a reduction of brain nonheme iron. The most prominent feature of ID is the significant and selective diminution of central dopamine neurotransmission resulting from the decreased number of dopamine D2 receptors in the caudate nucleus, nucleus accumbens, pituitary, and in all probability the frontal cortex. The consequences of diminished dopaminergic neurotransmission is a modification of dopamine-dependent behaviors and biochemical reactions, the most important of which is the reduction in learning processes. The role of iron in maintaining the homeostasis of normally functioning dopamine neurons and their involvement in cognitive processes cannot be excluded. An interference with iron metabolism at an early age can result in irreversible damage to developing dopamine neurons, with consequences that may manifest themselves in adult life.

Animals↗
PubMed1989

Brain iron: a lesson from animal models.

Brain and blood iron deficiency (ID) can be nutritionally induced. Significant behavioral and brain-biochemical changes are observed in rats rendered iron deficient, including complete reversal of the circadian cycles of motor activity, changes in thermoregulation and stereotyped behavior, and an increased pain threshold. The increase in pain threshold is affected by diurnal factors and peripheral treatment with beta-endorphin has a significant analgesic effect, implicating selective changes in the blood-brain barrier. These effects along with modifications in responses to dopaminergic drugs, interactions of ID with neuroleptic drugs, and modifications in behavior as a result of selective brain lesions, lead to two conclusions: this animal model is appropriate for human anemia and the best explanation for the variety of behavioral and brain biochemical changes in ID rats is that the principal effect of brain ID is a selective decrease in the functional level of the dopaminergic D2 system.

Amphetamine↗
PubMed1989

The use of the Morris Water Maze in the study of memory and learning.

Although the Morris Water Maze (MWM) was introduced only a few years ago, this technique has gained wide popularity, as the large number of publications in which it is employed, testifies. A review of the literature reveals that a wide variety of technical variables were used by the various research groups employing the MWM. This review describes the major changes in research variables, i.e., environmental variables, various manipulations, and the effects of diet or age on performance. The general principles of learning as demonstrated by the MWM are discussed.

Animals↗
PubMed1988

Recall of figure "A" of the Bender-Gestalt test among delinquents.

The Bender-Gestalt test was administered to 182 Israeli adolescent males: four groups of juvenile delinquents and two of nondelinquent high-school students. Each of the delinquent groups was administered one of the following versions: a standard administration with figure A first (n = 60), a change of sequence with figure A last (n = 22), a regular sequence with figure A changed to two adjacing circles (n = 20), and with figure A changed to two adjacent diamonds (n = 20). One nondelinquent group took the test under standard administration with figure A first (n = 30), and one took it with figure A last (n = 20). The results showed significantly low recall of the original figure A by delinquents when it appeared first. This phenomenon was related to both primary effect and the design depicted in figure A, with a greater influence of the latter. Difficulties in integration were suggested as inhibiting delinquents' recall.

Adolescent↗
PubMed1988

Acute and repeated gestational stress affect offspring learning and activity in rats.

This study assessed possible long-lasting effects of mild, indirect prenatal stress upon offspring. Dams were restrained for 30 minutes either once or four times during the third trimester of gestation. Their male offspring were challenged in adulthood with a series of appetitive operant learning tasks. Both acute and repeated prenatal maternal restraint retarded the performance of the offspring in a selective manner: deficits appeared during the reversal stage of an operant discrimination task, with no effect on acquisition, discrimination or extinction. Repeated, but not acute, maternal stress was also associated with offspring hyperactivity. This highlights the differential impact of varying the stress schedule. Furthermore, use of multiple measures of learning uncovered a long-lasting, selective effect of relatively mild, indirect prenatal manipulation.

Animals↗
PubMed1988

Selective alteration in blood-brain barrier and insulin transport in iron-deficient rats.

Nutritional iron deficiency induced in rats causes a significant reduction in level of brain nonheme iron and is accompanied by selective reduction of dopamine D2 receptor Bmax. Our previous studies have clearly demonstrated that these alterations can be restored to normal by supplementation with ferrous sulfate; however, neither brain nonheme iron level nor dopamine D2 receptor Bmax can be increased beyond control values even after long-term iron therapy. The possibility that iron deficiency can induce the breakdown of the blood-brain barrier (BBB) was examined. A 70 and 100% increase in brain uptake index (BUI) for L-glucose and insulin, respectively, were noted in iron-deficient rats. However, the BUI for valine was decreased by 40%, and those for L-norepinephrine and glycine were unchanged. In addition, it was demonstrated that in normal rats insulin is transported into the brain. The data show that iron deficiency selectively affects the integrity of the BBB for insulin, glucose, and valine transport. Whether the effect of iron deficiency on the BBB is at the level of the capillary endothelial cell tight junction is not yet known. However, this study has shown that an important nutritional disorder (iron-deficiency anemia) has a profound effect on the BBB and brain function.

Anemia, Hypochromic↗
PubMed1988

DSIP--a tool for investigating the sleep onset mechanism: a review.

Delta-Sleep-Inducing Peptide (DSIP) has several physiological effects in addition to its ability to promote sleep in animals under certain conditions. These effects include modification in thermoregulation, heart rate, blood pressure, pain threshold, and in the lymphokine system. DSIP effects are circadian cycle-dependent. Moreover, some of DSIP effects appear before neurological or behavioral signs of sleep. DSIP may promote peripheral preparatory physiological mechanisms associated with sleep onset.

Animals↗
PubMed1988

The circadian cycle effects of DSIP on colonic temperature, blood pressure, and heart rate in control and area postrema-lesioned rats.

Groups of control and Area Postrema rats were treated with 0.1 mg/kg, i.p., DSIP or with saline, at 06:00, 09:00, 12:00, 15:00, 18:00, 21:00, 24:00, and at 03:00. Colonic temperature, blood pressure, and heart rate were measured 30 min after treatment. DSIP induced a shift in the hyperthermic cycle of control rats, but was unable to modify the noncyclic hypothermia found among Area Postrema-lesioned rats. Furthermore, DSIP caused a decrease in the blood pressure level of control rats, but had no such effect on the already depressed level of blood pressure in the Area Postrema-lesioned rats. Finally, DSIP decreased the heart rate of control rats and significantly antagonized the elevated heart rate observed in the Area Postrema-lesioned rats. The data do not permit us directly to relate the physiological change induced by DSIP to its sleep-promoting effects.

Analysis of Variance↗
PubMed1987

Nutrients, brain biochemistry, and behavior: a possible role for the neuronal membrane.

Nutrients can modify brain biochemistry and behavior. Many studies indicate that one possible mode of action of nutrients is to induce alterations in the bioavailability of neurotransmitter precursors within the brain. However, a series of studies has also indicated that: (a) learning induces a decrease in the level of cholesterol in specific brain regions; (b) an iron-deficient diet induces changes in dopaminergic D receptor activity and in dopamine-associated behaviors (thermoregulation and motor activity) as well as in learning and memory capacities; and (c) dietary manipulation of a specific type of fatty acid resulted in an improved learning capacity, modification of the pain threshold level, and in thermoregulatory response. The most parsimonious explanation for these results seems to be that the treatments (learning, iron-deficient and fatty acid diets) induced changes in the lipid composition of the neuronal membrane. Such changes, in turn, resulted in changes in the membrane functions. Supportive evidence for this hypothesis is presented in this review. The "neuronal membrane functional modification hypothesis" should not be considered as contradictory to the accepted "brain neurotransmitter precursors bioavailability rates model" of nutrient effects, but as a complementary hypothesis.

Animals↗