Mario Tannhauser

Comparison of behavioral effects of moclobemide and deprenyl during forced swimming.

The present study compared the antiimmobility effects of l-deprenyl (DEP) and moclobemide (MOC) to the classic antidepressant imipramine (IMI), using an ethological approach. To investigate the degree of MAO-B inhibition by DEP and MOC, combination of treatments of ineffective doses of phenylethylamine (PHEA) with DEP or with MOC were administered in three doses before immobility was tested in the forced-swimming paradigm. Tests were videotape recorded for analysis of the frequency and duration of the behaviors during the procedure. There was a significant, dose-dependent decrease in immobility duration and an increase in mobility duration of rats treated with IMI. Both active behaviors of climbing and swimming were equally enhanced by the tricyclic antidepressant, climbing behavior composing 75% of the mobile behaviors. The intermediate doses of the MAOIs tested, DEP 0.25 mg/kg and MOC 30 mg/kg, decreased immobility and increased mobility. The antiimmobility effect of DEP was due to longer climbing behavior while MOC enhanced swimming duration. No behavioral changes were seen with the administration of the lower and higher doses of the MAOI. Potentiation of the antiimmobility effects was observed when ineffective doses of PHEA and of DEP or MOC were administered in combination. Differences between the MAO inhibitors on the active behaviors were also observed when administered with PHEA; DEP and PHEA significantly increased climbing and MOC and PHEA increased swimming. This preclinical evaluation of selective MAO inhibitors indicates that both MAO-A and MAO-B inhibitors have antidepressant effects. However, to clearly demonstrate that these antiimmobility effects are a consequence of increased brain concentrations of any one of the several monoamines implicated in the mechanism of action of DEP or MOC should be the subject of future studies.

Enhanced detection of hyperactivity after drug withdrawal with a simple modification of the open-field apparatus

The open-field apparatus has been used to study withdrawal reactions from chronic treatments with central nervous system depressant drugs. To study the behavior of the same animal after drug withdrawal, the rats are introduced into the open field on consecutive days. Because the open field is a novel environment, the repetition could lead to false-negative results with regard to drug withdrawal. To overcome this problem, we sought a modification of the open field, using different floor-painting patterns every time the animal is observed. The most frequently observed withdrawal manifestation was hyperactivity. We verified that long-term treatment withdrawal reactions from barbital, clonazepam, and ethanol were seen more often if the rats were introduced in the modified open field. In addition, fewer animals were used here than in other trials and hyperactivity was detected more frequently in the modified open field than was sound-induced convulsions. We propose that the modified open field is more useful than the classic one for screening of drug withdrawal reactions.

Effect of morphine on the RNA and ATP concentration of brain structures of the rat.

The effect of morphine on rat cortical, hippocampal, thalamic, and hypothalamic RNA and ATP concentration was studied. After a single dose (10 mg/kg, i.p.) there was an increase of RNA in the cortex and thalamus, and a decrease of ATP levels in both structures. When the drug was given chronically (daily injections during 10 days at increasing doses from 10 to 100 mg/kg), only a fall of thalamic RNA and an increase of thalamic ATP were observed relative to saline-treated controls. Rats which received the chronic saline treatment, however, had higher hippocampal thalamic RNA and levels and a lower thalamic ATP concentration than those which received a single saline Injection.

Toxicologia do tolueno: aspectos relacionados ao abuso

O tolueno esta presente em muitos produtos de uso domestico e industrial e e o principal solvente envolvido no abuso de substâncias e na exposicao ocupacional. O problema mais grave no estudo de patologias relacionadas ao tolueno e que este esta geralmente associado, em suas preparacoes comerciais, a outras substâncias. O potencial toxico do tolueno foi abordado nos seguintes aspectos: parâmetros farmacologicos; caracteristicas fisico-quimicas; exposicao; estudos clinicos; diagnostico; pesquisa experimental; tolerância e dependencia; efeitos agudos e cronicos; neurotoxicidade; teratogenicidade; doencas psiquiatricas; carcinogenicidade e tratamento. Conclui-se ser de grande importância e urgencia que se realizem estudos clinicos com amostras maiores para definicao mais precisa das consequencias do uso cronicoToluene, present in many industrial and domestic products, is the main solvent involved in solvent abuse and occupational exposure. The main problem in studying toluene-related pathologies is the fact that it is frequently combined with other substances. This review focuses on its potential toxicity. The following subjects are discussed: pharmacologic parameters; physico-chemical features; exposure; clinical trials; experimental research; diagnosis; tolerance and dependence; acute and chronic effects; neurotoxicity; teratogenicity; psychiatric disorders; carcinogenicity; and treatment. It is concluded that is important more research on larger population samples with a view to better definition of the consequences of chronic use should be undertaken.

Lack of Tolerance to Imipramine or Mianserine in Two Animal Models of Depression

Few clinical reports describe tolerance induced by antidepressants and this question is considered an unsolved problem for clinical use of this group of drugs. The present report deals with the effects of imipramine and mianserine on two animal models of depression, after acute or prolonged previous treatment with these antidepressants. Imipramine and mianserine potentiated amphetamine-induced anorexia both after acute administration or after prolonged previous treatment with each drug. Mianserine effects were not detected in the behavioral despair test and imipramine reduced rats immobility equally after acute and prolonged previous treatment. It was concluded that imipramine and mianserine do not induce detectable tolerance when previously administered to animals submitted to amphetamine anorexia or behavioral despair.

Effect of Seizures and Anticonvulsant Agents on Hippocampal RNA Concentration

Epileptogenic stimulation of the fornix during 25 min caused a fall of total hippocampal RNA concentration in rats. This fall was prevented by the preadministration of phenobarbital, trimethadione, di