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J Palermo-Neto

Publications and source records attributed to J Palermo-Neto.

88 records · Page 5Linked to original sources
PubMed1985

A biochemical study of cholinergic-dopaminergic interactions in the central nervous system.

The effects of cholinergic (Ach) and anti-Ach drugs on striatal dopamine (DA) levels and turnover were studied. Treatment with both atropine sulfate and scopolamine hydrobromide increased striatal DA levels; scopolamine increased striatal DA turnover and decreased both striatal 3,4-dihydroxyphenylacetic acid (DOPAC) levels and DOPAC/homovanillic acid (HVA) relation. Oxotremorine decreased striatal DA levels but did not change striatal DA turnover or DA metabolites. Changes in striatal DA levels or turnover were not observed after atropine methyl nitrate or physostigmine. The data show the Ach-DA interactions in the striatum.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1985

Differential alterations in brain sensitivity to amphetamine and pentylenetetrazol in socially deprived mice.

Mice deprived of social interactions for different periods of time (56, 69, 79, 89 or 97 days) were studied. Social isolation increased both general activity observed in an open-field and amphetamine-induced hyperactivity; CNS responsiveness to pentylenetetrazol-induced convulsions, however, decreased. The differences in general activity were detected after 69 and 79 days of social deprivation; the hyperactivity induced by amphetamine was greater after 79 days of isolation and the pentylenetetrazol CD50's were higher after 56, 69 and 79 days of solitude. These data, obtained with mice, show first that isolation time is an important variable to display drug effects and secondly that long-term deprivation of social stimuli does not increase CNS susceptibility to all stimulant drugs. A combination of a higher release of catecholamines onto previously supersensitive receptors was considered to be involved with the differences observed.

Amphetamine↗
PubMed1985

Social isolation and tolerance development to sodium barbital in mice.

The effect of the duration of isolation periods on the development of tolerance to sodium barbital was studied in mice. The HD50 values for pentobarbital-induced hypnosis were higher in all mice that were long-term treated with sodium pentobarbital, whether or not they were isolated or in groups. Diazepam HD50s were higher in mice isolated and long-term treated with sodium barbital for 38 days and in grouped animals treated with the barbiturate for 20 and 30 days. Social isolation for 8 weeks plus 23 days increased the pentobarbital hypnotic dose (HD50). These data show that social isolation increased the rate of tolerance acquisition to sodium barbital by mice.

Animals↗
PubMed1984

Effects of apomorphine administration on rearing activity of control and experimental rats withdrawn from long-term haloperidol treatment.

Rats were administered increasing doses of haloperidol or control solution for 25 days. 72 hr after drug withdrawal they were observed for rearing activity in an open field with or without apomorphine treatment. Rearing frequency was higher in haloperidol withdrawn rats. In control rats rearing frequency decreased 15 min after apomorphine administration in a dose-dependent way. In haloperidol withdrawn animals the apomorphine effects were dual, first an increase in rearing frequency induced by the smaller apomorphine doses (0.025-0.1 mg/kg) was observed and secondly a progressive and dose-dependent decrease was scored. Apomorphine also induced different motor effects not necessarily similar in control and experimental rats. Supersensitivity of dopaminergic receptors induced by the long-term neuroleptic administration was considered to be involved with the difference observed.

Animals↗
PubMed1984

Kinetic analysis of central nervous system supersensitivity induced in rats by long-term haloperidol administration. I. pA2 determination.

A kinetic analysis of central dopamine receptors in control and in experimental rats, withdrawn from long-term haloperidol treatment was made in vivo. Using the stereotyped behavior induced by apomorphine administration as the response, the relative affinity of metoclopramide as reflected by pA2 values, was examined in normal and supersensitive rats. Metoclopramide antagonized apomorphine stereotypy in a dose-dependent and competitive manner. At each dose tested, metoclopramide produced a larger rightward shift of the apomorphine dose-response curve in the control rats than in withdrawn rats. The Schild plot resulted in a straight line, the slopes being -1.2 +/- 0.3 and -0.8 +/- 0.2 for control and experimental rats, respectively. These findings suggest a decrease in receptor affinity after long-term haloperidol treatment, a concept not demonstrated in binding studies in vitro.

Animals↗
PubMed1983

Effects of apomorphine administration on locomotor activity of control and experimental rats withdrawn from long-term haloperidol treatment.

Rats were administered increasing doses of haloperidol or control solution for 25 days, 72 hr after drug withdrawal they were observed for locomotor activity in an open field with and without apomorphine treatment. Locomotion frequency was higher in haloperidol withdrawn rats. In both groups locomotion frequency decreased 15 min after apomorphine administration, in a dose-dependent way. Apomorphine induced, also, different motor effects not necessarily similar in control and experimental rats. Supersensitivity of dopaminergic receptors induced by the long-term neuroleptic administration was considered to be involved with the differences observed.

Animals↗
PubMed1983

Central nervous system supersensitivity and withdrawal from long-term diphenylhydantoin treatment.

The effects of withdrawal from long-term treatment with increasing doses of diphenylhydantoin (DPH) were studied in rats. The dose of DPH was increased from 5 to 200 mg/kg over 20 days and the animals were tested 72 h after withdrawal. DPH withdrawal induced a leftward displacement of the dose-response curves obtained for the convulsive effects of both picrotoxin and metrazol and decreased the latency of 3-mercaptopropionic acid-induced seizures. These effects were interpreted to be a consequence of supersensitivity of the central nervous system induced by long-term DPH depression.

Animals↗
PubMed1982

Effects of withdrawal from long-term barbital treatment on open-field behaviour and seizure susceptibility of rats.

Rats withdrawn from long-term barbital treatment were tested both for their activity in an open-field and for their sensitivity to convulsant stimuli. Barbital withdrawal induced a significant increase on locomotion and rearing frequency. Drug removal also made the rats more sensitive to convulsions elicited by sound and maximal electroshock. A positive correlation was found between locomotion plus rearing frequency and audiogenic-induced seizures 3, 4 and 5 days after barbital withdrawal. The results show that exploratory behaviour evaluated through the open-field method can be used as a reliable method to show barbital withdrawal in rats. Taken together, the results suggest that long-term barbital treatment might develop a supersensitivity state, in noradrenergic neurons in the central nervous system.

Acoustic Stimulation↗
PubMed1982

A quantitative study of cholinergic-dopaminergic interactions in the central nervous system.

The effects of cholinergic (Ach) and anti-Ach drugs on stereotyped behavior induced by apomorphine administration were studied quantitatively. Dose-response curves were constructed to apomorphine and the horizontal shifts of the experimental curves induced by the different treatments were measured at the level of ED50 of apomorphine. Treatment with both atropine sulfate and scopolamine hydrobromide induced a leftward displacement of the dose-response curve; physostigmine and oxotremorine displaced the curve to the right. Changes in stereotypy were not observed after atropine methyl nitrate. It is concluded that the activity of acetylcholine-containing neurons may exert a modulatory influence on dopaminergic systems.

Acetylcholine↗
PubMed1982

Effects of alpha-adrenergic blocking agents on stereotyped behavior induced by apomorphine in rats.

1. The effects of alpha-adrenergic blocking agents on stereotyped behavior induced by apomorphine in rats were studied. 2. Pretreatment of rats with 5 and 10 mg/kg of phenoxybenzamine or phentolamine displaced the dose-response curves for apomorphine-induced stereotypy to the left in a dose dependent manner. The ED50 for apomorphine was reduced from 1.92 +/- 0.38 (mean +/- SEM) to 0.63 +/- 0.08 by 10 mg/kg phenoxybenzamine and from 1.92 +/- 0.38 to 0.61 +/- 0.10 by 10 mg/kg phentolamine. 3. These results support the view that the expression of dopaminergic-induced stereotyped behavior is dependent on noradrenergic activity in the central nervous system.

Animals↗
PubMed1981

The effects of scopolamine pretreatment on stereotyped behavior induced by apomorphine in rats withdrawn from long-term haloperidol administration.

1. The effects of scopolamine on intensity of stereotyped behavior induced by the ED50 dose of apomorphine in controls and in animals withdrawn from long-term haloperidol treatment were studied. 2. Doses of 1.0 and 3.0 microgram/kg of scopolamine increased apomorphine-induced stereotypy in both groups. However, this increase was smaller in the haloperidol-treated than in the control animals. 3. These data support the hypothesis that long-term administration of haloperidol may produce a change not only in dopaminergic but also in central cholinergic receptor sensitivity.

Animals↗
PubMedDate not supplied

Developmental and behavioral effects of prenatal amitraz exposure in rats.

The effects of prenatal amitraz exposure on physical and behavioral parameters of rats were studied. Pregnant rats were orally gavaged with amitraz (20 mg/Kg) or with distilled water (1.0 ml/Kg) on Days 1, 4, 7, 10, 13, 16, and 19 of pregnancy. After birth, cross-fostering was performed thus generating the following groups: control pups nursed by control dams (CC); control pups nursed by treated dams (CE); treated pups nursed by treated dams (EE) and treated pups nursed by control dams (EC). Results show that compared to pups of Group CC, groups prenatally exposed to amitraz (EC and EE) showed decreased age of vaginal opening. Group EE also showed earlier fur development and a delay in incisor eruption compared to Group CC. The ages of pinna detachment, eye and ear opening, testes descent, and reflex development (surface righting and startle) were not affected by amitraz exposure. Offspring of group CE also showed earlier fur development. Rats of group EE had higher locomotor activity and rearing frequency and shorter immobility time compared to the rats of group CC when observed in an open-field 30 days after birth but not 60 and 90 days. No significant differences were found in open-field behaviors among the CC, CE, and EC groups. The present findings indicate that prenatal exposure to amitraz caused transient developmental and behavioral changes in the exposed rat offspring and suggest that further investigation of the potential health risk of amitraz exposure to developing human offspring may be warranted.

Animals↗
PubMedDate not supplied

Toxicology of 2,4-dichlorophenoxyacetic acid (2,4-D) and its determination in serum and brain tissue using gas chromatography-electron-capture detection.

A gas-liquid chromatographic method with an electron-capture detector was applied for 2,4-dichlorophenoxyacetic acid (2,4-D) determination in the serum and brain tissue of rats acutely intoxicated with the dimethylamine salt of 2,4-D. After extraction with ethyl ether, 2,4-D derivatization was performed using 2-chloroethanol and BCI3. The average recovery values found for serum and brain tissue were 98.5 +/- 4.8 and 93.3 +/- 7.5, respectively. The sensitivity limit of the method was 250 ng/mL for serum and 300 ng/g for brain tissue. The toxic effects of 2,4-D in rats were observed within one-half hour after its oral administration. Results suggest that the toxic mechanism of 2,4-D is related to an action on the central nervous system.

2,4-Dichlorophenoxyacetic Acid↗