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S Yehuda

Publications and source records attributed to S Yehuda.

At least 55 records · Page 3Linked to original sources
PubMed1987

Effects of alpha-MSH, TRH and AVP on learning and memory, pain threshold, and motor activity: preliminary results.

The effect of daily peripheral administration of various peptides on learning and memory performance was studied in male albino rats. Groups of rats were treated with either TRH (1.0 mg/kg) alpha-MSH (1.0 mg/kg), or saline for three days. Other groups were treated either with vasopressin (1.0 microgram/kg) or saline. All treatments were 30 min before testing in a Morris Water Task apparatus. This type of learning is spatial learning which requires integration of environmental cues. Only alpha-MSH treated rats exhibited improved learning on Day 1 and Day 3 of the training period. One month later all rats were retested with no difference between the experimental groups. Single doses of these peptides caused a nonsignificant increase in pain threshold. The body weight gain of vasopressin-treated rats was significantly reduced as well as their motoric behavior. Therefore, the alpha-MSH effect on learning cannot be explained by nonspecific effects on body weight, pain threshold, or motor activity level.

Animals↗
PubMed1987

Effects of dietary fats on learning, pain threshold, thermoregulation and motor activity in rats: interaction with the length of feeding period.

The effects of both a semisynthetic diet containing 20% fat from various sources (soybean oil, sunflower oil and lard) and a control diet on learning capacity, motor activity, pain threshold and thermoregulation were studied in rats which were fed on these diets for various lengths of feeding periods (1, 2, 3 and 4 weeks). Two weeks feeding period of soybean oil source induced an improvement in learning capacity, which was further enhanced by increasing the length of the feeding period. A 3-week feeding period was required to obtain an increase in the pain threshold, by which time the rats were also protected from d-amphetamine induced hypothermia. The analgesia induced by the diet is naloxone-dependent. None of the other diets, including the sunflower oil diet, which is richer in polyunsaturated fatty acids, differed from control diet. While the mode of action of this diet is still unknown, the effects of the soybean oil source diet cannot be attributed to nutritional factors such as changes in energy consumption or body weight.

Animals↗
PubMed1986

Learning is improved by a soybean oil diet in rats.

A semi-synthetic diet containing 20% polyunsaturated fat (soybean) oil was fed to young male hooded rats for 21 days. These animals exhibited improved performance on an environmentally-cued testing paradigm which is thought to reflect cognitive learning skills (i.e., Place Navigation Water Task). Other rats fed the same base diet but containing 20% saturated fat (lard) showed no such improvement compared to chow-fed (4.5% mixed fat) controls. The animals fed soybean oil also exhibited a transient resistance to extinguish this learning. This improved learning could not be explained by changes in general motor activity, basal body temperature, energy consumption, body weight, or in the brain activity of choline acetyltransferase, the marker enzyme for cholinergic neurons. These findings constitute the first evidence that short-term variations in the quality of dietary fat can enhance mammalian learning.

Animals↗
PubMed1986

In vivo modulation of brain cholesterol level and learning performance by a novel plant lipid: indications for interactions between hippocampal-cortical cholesterol and learning.

In this account we report in vivo effects of a plant lipid preparation (MMPL) on brain cholesterol and the activity and learning performance of aging male rats. Three-month-old rats were fed for 3 months with a diet that was enriched with 3% MMPL. Another group of 18 month-old rats was fed for 6 months with a 3% MMPL-enriched diet. This food regime lowered markedly the cholesterol level in the hippocampal and cortical regions and increased their lipid membrane fluidity. The animals of both age groups also responded to MMPL with a higher activity and their learning performances, compared to normal diet-fed animals, improved notably. This improvement continued at least 4 months after terminating the supply of MMPL. Significant inverse correlationships were obtained between the length of the training period required to attain proper criteria and cholesterol levels of the hippocampal and cortical brain fractions.

Activity Cycles↗
PubMed1986

Brain iron-deficiency causes reduced learning capacity in rats.

Rats made nutritionally iron-deficient (ID) showed a significant deficit in water-maze learning compared with normal rats. The deficit was substantially greater the longer the rats stayed on the ID diet. The deficit in learning was established prior to any significant decrease in hemoglobin (Hb) level in the blood. Three weeks after the ID rats were placed on a control diet, the Hb level was restored to normal value, but the cognitive deficit remained. Previous studies showed that the behavioral effects of ID are mediated by a decrease in the functional activity of the dopaminergic system. The ID effects on learning and memory may be related to the irreversible diminished dopaminergic neurotransmission that results from ID.

Animals↗
PubMed1986

Effects of dietary fat on pain threshold, thermoregulation and motor activity in rats.

Groups of young male Sprague-Dawley (albino) or Long-Evans (hooded) rats were fed the same semi-purified diets containing 20% (w/w) fat in the form of soybean oil vs. lard, or a reference diet of standard Purina Chow (4.5% mixed fats) for 21 days. Behavioral testing after this time revealed that albino rats fed the diet containing soybean oil had increased paw-lick latencies on a 58 degrees C hot plate compared to chow-fed rats. In addition, both strains fed the diet containing soybean oil were protected from hypothermia induced by placing animals in a 4 degrees C cold room for 60 min following systemic injection of 10-15 mg/kg d-amphetamine. Rats of both strains fed the lard diet displayed paw-lick latencies similar to those shown by rats fed chow and hypothermic changes intermediary to those shown by rats fed soybean oil vs. chow diets. Horizontal crossings as well as rearings in a 15 min test of open field activity were the same for all diet groups within strains. No substantial differences were observed in the number of calories consumed, amount of body weight gained or basal colonic temperatures across diet conditions. The results suggest that a soybean oil-based diet can alter physiological mechanisms which mediate these indices of pain perception and thermoregulation. More generally, they indicate that qualitative changes in dietary fat content may be capable of altering certain behavioral states.

Amphetamine↗
PubMed1985

The involvement of the two hemispheres in the reaction time to central and peripheral visual stimuli.

Central and peripheral visual stimuli were presented randomly to subjects in three situations: (a) two eyes open; (b) only left eye open and (c) right eye open. The main finding is slower reaction time to right peripheral visual stimuli observed in one eye. No correlation was found between reaction time and scores on the Type A behavior test. The role of the right hemisphere in mediating this effect is discussed.

Adult↗
PubMed1985

Learning-induced changes in brain membrane cholesterol and fluidity: implications for brain aging.

Studies were conducted to elucidate effects of learning on properties of brain membranes. Sprague-Dawley rats, (3-months-old) fed with normal Purina chow cakes, were trained in a T-maze. After reaching proper criteria, the animals were sacrificed, their brains dissected into hypothalamus, hippocampus, cortex and brainstem. The various brain regions were assayed for cholesterol, phospholipids and membrane lipid microviscosity. The salient findings were (a) a marked learning-induced decrease in the level of cholesterol in the hippocampal and cortical regions and (b) a learning-induced increase in the membrane lipid fluidity. We postulate that upon the learning impact, brain membranes undergo definite changes in the lipid membrane phase which participate in the transduction of the learning process into biochemical templates.

Aging↗
PubMed1985

Flufenamic acid in prostaglandin migraine.

A new class of migraine symptomatology is suggested which consists of major signs of migraine related to disturbances in the menstrual cycle. Not only are these patients different from other migraine patients, they are most responsive to an antiprostaglandin drug. This drug is less useful in other forms of migraine. We suggest that this type of migraine be called prostaglandin migraine.

Adult↗
PubMed1984

The increased opiate action of beta-endorphin in iron-deficient rats: the possible involvement of dopamine.

Rats made nutritionally iron-deficient (ID) have been shown to have a lower brain non-haem. A selective diminution of the binding capacity of the D2-dopaminergic receptors alone was found among nutritionally iron-deficient rats. Peripherally administered beta-endorphin significantly elevated the pain threshold only in the iron-deficient rats. Naloxone blocked the beta-endorphin effect in ID rats. Morphine, as well as haloperidol, elevated the pain threshold in both the iron-deficient and the control rats but significantly more in the former group. No additive effects of combined treatment with beta-endorphin and haloperidol on pain threshold were found. Other neuroleptics also elevated the pain threshold. A possible hypothesis is that dopamine (via beta-endorphin) may play a role in modifying the pain threshold.

Animals↗
PubMed1984

Cognitive asymmetries after wakings from REM and NONREM sleep in right-handed females.

Eleven right-handed females were awakened from REM and NONREM sleep and tested on three tests designed to measure functions attributed to the left hemisphere and on three tests designed to measure right hemisphere function. A significant shift in cognitive profile was found in the direction of right hemisphere dominance after waking from REM sleep, and left hemisphere dominance after waking from NONREM sleep. Comparison of the cognitive shifts in females to that observed in males revealed a significant interaction of gender and awakening condition. Females showed a larger increase in right hemisphere performance following awakening from REM sleep relative to NONREM sleep, and a smaller increase in left hemisphere performance following awakening from NONREM sleep relative to REM sleep. The reverse trend was found for males.

Adult↗
PubMed1984

Modulation of dopamine receptor in the striatum by iron: behavioral and biochemical correlates.

The present study has shown that in the rat brain iron is unevenly distributed and may be associated with the dopaminergic neuron. The function of the large amounts of iron in certain brain areas, such as the pallidum, caudate nucleus, substantia nigra, nucleus accumbens, and olfactory tubercule, is not known. But it is obvious that by reduction of brain iron, as in the case of nutritional iron deficiency, certain dopamine-mediated behavioral phenomena and biochemical reactions are altered. These changes have been attributed to the selective reduction in dopamine D2 receptors and function in brain areas rich in dopamine neurons and iron. If iron is especially important to dopaminergic modulatory systems in the brain, its deficit might explain the increasing number of reports on behavioral disturbances, EEG, and event-related potentials (ERPs) associated with nutritional iron deficiency in children.

Animals↗
PubMed1983

Indolamine hallucinogens as MAO inhibitor agents--theoretical approach.

A new theoretical hypothesis on the mode of action of LSD and other hallucinogens of the indolamine family is proposed. In view of the suggestions that LSD acts both on the 5-HT system as an antagonist and on the DA system as an agonist, we suggest that in addition to 5-HT blocking capacity, LSD and the other indolamine hallucinogens act as MAO inhibitors.

Amines↗
PubMed1983

Brain iron and dopamine receptor function.

It has been demonstrated that nutritional iron-deficiency induced in rats results in the reduction of DA D2 receptor binding sites, leading to down-regulation of dopaminergic activity similar to that observed in neuroleptic-treated animals. The following observations are common to both conditions: (a) Decreased behavioural response to pre- and post-synaptically DA and serotonin acting drugs, amphetamine, apomorphine and 5-methoxy-N,N-dimethyltryptamine. (b) Inhibition of amphetamine or apomorphine induced hypothermia in rats kept at an ambient temperature of 4 degrees C. (c) Increased sleeping time to phenobarbitone which cannot be attributed to the rate of drug metabolism (5,38). (d) Upregulation of prolactin binding sites in the liver as a result of increased serum prolactin. Additionally, nutritional iron-deficiency lowers brain iron and interferes with protein synthesis in this organ, which could explain the reduction of DA D2 receptor number and function. Given the fact that the highest brain concentrations of iron are found in dopaminergic structures (see 42 for review), and the essential role of intact dopaminergic systems to attentional and learning processes (15b,30), the resultant behavioural changes due to the reduction of dopaminergic activity in iron-deficient animals may go some way to explain the adverse effects on cognition, behavioural patterns, learning and attention, event-related potentials (ERPs) and EEG changes reported in iron-deficient children (19-28,30).

Anemia, Hemolytic↗
PubMed1982

Possible serotonergic mediation of induction of sleep signs by DSIP and by d-amphetamine.

Although the peripheral administration of DSIP (delta sleep inducing peptide) to intact animals does not consistently induce behavioral sleep, potentiation of the effect by d-amphetamine has been established earlier. This study investigated DSIP effects in rats following pretreatment with alpha MPT and/or 1-tryptophan at various dose levels. A clear potentiation was found. Furthermore, pretreatment with methysergide blocked the emergence of sleep signs in various treated groups. It is proposed that the action of DSIP is best understood in the context of mediation via serotonergic mechanisms.

Animals↗