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Biomedical subjects

S Tufik

Publications and source records attributed to S Tufik.

14 recordsLinked to original sources
PubMed1991

Effects of selective adrenoceptor agonists and antagonists on aggressive behavior elicited by apomorphine, DL-dopa and fusaric acid in REM-sleep-deprived rats.

REM sleep deprivation (REMSD) results in behavioral changes such as the appearance of affective aggression induced by apomorphine (APO) and other dopaminergic agents. REMSD modifies dopamine-mediated behavior as well as the adrenergic receptor sensitivity. This paper evaluates the interaction between these two neurotransmission systems through changes in APO-, DL-DOPA- and fusaric acid (FA)-induced aggressive behavior in REMSD rats pretreated with phentolamine, propranolol, metaraminol, prazosin, clonidine, yohimbine, isoproterenol, butoxamine and maprotiline. Only isoproterenol reduced FA-induced aggressiveness. No specific changes in aggressiveness were noticed with other treatments and not even inhibitors of norepinephrine transmission induced aggressive behavior. It is concluded that norepinephrine had a slight inhibitory action on aggressiveness elicited by dopaminomimetic agents in REMSD rats. Beta-adrenoceptors could be responsible for this effect since only beta-selective drugs reduced aggression. As REMSD reduces beta-adrenoceptor sensitivity, only minor changes in aggressiveness could be observed. It was noted that the three drugs used to induce aggressive behavior elicited different patterns of aggression.

Aggression↗
PubMed1990

Effects of REM sleep deprivation of ACTH-induced yawning.

Central administration of ACTH in rats induces yawning and stretching. In order to study the effects of REM sleep deprivation on ACTH-induced yawning, the peptide was injected immediately after the REM sleep deprivation period or 24 h later. REM sleep deprivation impaired ACTH-induced yawning, but after a 24-hour recovery period, rats displayed a number of yawns similar to those in control animals. Implications for an involvement of dopaminergic and mainly cholinergic systems are discussed.

Adrenocorticotropic Hormone↗
PubMed1988

Reversal of the increase in apomorphine-induced stereotypy and aggression in REM sleep deprived rats by dopamine agonist pretreatments.

REM sleep deprivation (REMSD) induces augmented responses to dopaminergic agonists. Prolonged administration of neuroleptics induces a similar state, probably by the production of supersensitivity of dopaminergic receptors. Such a supersensitive state could be induced by REMSD as a result of impairment of dopamine neurotransmission. In order to test this hypothesis, bromocriptine, nomifensine, amphetamine, L-dopa, imipramine and electroconvulsive shock (ECS) were administered to rats during REMSD, and aggressive and stereotyped behaviors were measured. Amphetamine and L-dopa pretreatment attenuated the increases in apomorphine-induced stereotypy and aggression in REMSD rats, but ECS selectively reduced apomorphine-induced aggression. The other drugs tested were ineffective on both behavioral tests. Such a selective action may reflect different effects of ECS on different dopaminergic systems such as those involved with stereotypy and aggression. The results suggest that REMSD induces an increase in dopaminergic sensitivity which may be reversed by pretreatment with some dopaminergic agonists.

Aggression↗
PubMed1987

Does REM sleep deprivation induce subsensitivity of presynaptic dopamine or postsynaptic acetylcholine receptors in the rat brain?

Yawning behavior was used to evaluate the sensitivity of presynaptic dopamine receptors and postsynaptic acetylcholine receptors of normal and REM sleep-deprived (REMSD) rats. The results show a lowering of the dose-response curve obtained with apomorphine and pilocarpine, as well as a shift to the right in the curve obtained with physostigmine. These results suggest that REMSD induces subsensitization of presynaptic dopamine receptors and/or postsynaptic acetylcholine receptors with different characteristics related to the mechanism of action of the cholinomimetic agent employed.

Animals↗
PubMed1987

Rem sleep deprivation in an experimental model of Parkinson's disease.

Previous investigations have shown that REM sleep deprived (REM SD) rats display an enhanced response to dopamine agonists. This action seems to be mediated through a supersensitivity of dopamine post-synaptic receptors. Accordingly, REM SD was performed on rats with an experimental model of Parkinson's disease. The animals were bilaterally lesioned in the nigrostriatal pathway through a stereotaxically directed electrical current. Seven days after the surgery the animals were REM SD for 72 hours and immediately after the end of this period were observed in an open field for ambulation, rearing, grooming, and latency. In comparison with non-deprived rats there was a significant increase in ambulation and rearing, a response that appeared again after a second REM SD period on day 21th after the surgery. These data of improvement of two parameters of an experimental model of Parkinson's disease suggest that SD may be useful in this condition.

Animals↗
PubMed1986

REM sleep deprivation induces a decrease in norepinephrine-stimulated 3H-cyclic AMP accumulation in slices from rat brain.

Beta adrenergic sites in rat brain are reduced after repeated treatment with antidepressant drugs, with REM sleep deprivation (REMSd) having the same effect. This paper reports the effects of REMSd in the production of 3H-cyclic AMP in frontal cortical slices by NE challenge. Data presented in this paper report a marked decrease in 3H-cyclic AMP synthesis after REMSd, which is in accordance with previous results showing adrenergic receptor down-regulation following REMSd. Results are discussed in view of possible interaction with dopaminergic systems and depression management.

Adenylyl Cyclases↗
PubMed1986

Pharmacology of lemongrass (Cymbopogon citratus Stapf). III. Assessment of eventual toxic, hypnotic and anxiolytic effects on humans.

A herbal tea (called an abafado in Brazil) prepared from the dried leaves of lemongrass was administered to healthy volunteers. Following a single dose or 2 weeks of daily oral administration, the abafado produced no changes in serum glucose, urea, creatinine, cholesterol, triglycerides, lipids, total bilirubin, indirect bilirubin, GOT, GPT, alkaline phosphatase, total protein, albumin, LDH and CPK. Urine analysis (proteins, glucose, ketones, bilirubins, occult blood and urobilinogen) as well as EEG and EKG showed no abnormalities. There were slight elevations of direct bilirubin and of amylase in some of the volunteers, but without any clinical manifestation. These results taken together indicate that lemongrass as used in Brazilian folk medicine is not toxic for humans. The eventual hypnotic effect of lemongrass was investigated in 50 volunteers who ingested samples of lemongrass and a placebo under double-blind conditions. The parameters (i.e. sleep induction, sleep quality, dream recall and rewakening) did not show any effect of lemongrass as compared to the placebo. Eighteen subjects with high scores of trait-anxiety were submitted to an anxiety-inducing test following taking lemongrass or placebo under double-blind conditions. Their anxiety levels were similar, indicating that the abafado of the plant does not have anxiolytic properties. It is concluded that lemongrass, one of the most popular Brazilian herbal medicines, used for its alleged CNS-depressant effects, is atoxic but lacks hypnotic or anxiolytic properties.

Administration, Oral↗
PubMed1978

Does REM sleep deprivation induce a supersensitivity of dopaminergic receptors in the rat brain?

The possibility that REM sleep deprivation induces increased sensitivity of rats to the effects of apomorphine was investigated. Rats were deprived of REM sleep by placing them on 6.0 cm platforms for 3 days. Stress control groups consisting of rats placed on 14 cm platforms (control rats) and groups of nonmanipulated animals (normal rats) were used for comparison purposes. Several doses of apomorphine were administered to these 3 groups of animals, and aggressive behavior, stereotyped behavior, verticalization and body temperature were recorded. All measures indicated that REM-deprived rats were more responsive to apomorphine than the normal and control animals, with the exception of verticalization effect, in which both REM-deprived and control animals reacted similarly. These results suggest that REM deprivation induced supersensitivity in brain dopamine receptors. Other possible interpretations are also discussed.

Aggression↗
PubMed1977

Cannabis, catecholamines, rapid eye movement sleep and aggressive behaviour.

1. Previous work from our laboratory has shown that cannabis induces aggressive behaviour in rats that have been deprived of rapid eye movement (REM) sleep. It was suggested that this effect was related to brain catecholamines, with dopamine playing an agonist role and noradrenaline an inhibitory one. The present paper describes new experiments dealing with this subject. 2. Previous REM sleep-deprivation enhanced both delta9-tetrahydrocannabinol (THC)-induced hypothermia and nomifensine effects on aggressive behaviour. 3. A marihuana extract decreased brain dopamine turnover in REM sleep-deprived rats, an effect not observed in non-deprived rats. Noradrenaline metabolism was not altered. 4. Fighting behaviour was elicited in REM sleep-deprived rats treated with 4 different dopamine-beta-hydroxylase inhibitors. 5. Apomorphine, nomifensine and delta9-THC administered to non-deprived rats pretreated with bis(4-methyl-1-homopiperanzinyl-thiocarbonyl) disulphide (Fla-63), induced fighting behaviour. 6. Nomifensine and apomorphine induced fighting in non-deprived rats pretreated with delta9-THC. 7. Clonidine inhibited the fighting elicited in REM sleep-deprived rats by either delta9-THC or Fla-63 pretreatment. 8. The data are discussed in terms of the influence of REM sleep-deprivation (or the stress associated with deprivation) on the response to dopaminergic drugs and cannabis. Taken together they emphasize the participation of brain dopamine and noradrenaline systems in the aggressive behaviour studied.

Aggression↗
PubMedDate not supplied

Modifications on dopaminergic and cholinergic systems induced by the water tank technique: analysis through yawning behavior.

Animals deprived of REM sleep by the water tank technique show an important decrease in frequency of yawning, induced by dopaminergic (apomorphine in low doses) and cholinergic (physostigmine and pilocarpine) agonists, if they are tested immediately after the 96 hr of deprivation. In order to understand the mechanisms underlying the effects of REM sleep deprivation on dopaminergic and cholinergic systems, we decided to test the animals after a recovery period of 24 hr. It was observed that apomorphine-induced yawning was still significantly reduced, whereas pilocarpine-induced yawning had returned to normal. The findings suggest that REM sleep deprivation alters dopaminergic and cholinergic systems in different ways: it seems that the interference on the dopaminergic system is prior and stronger than on the cholinergic system, thus its recovery demands more time.

Animals↗