Biomedical subjects

J Palermo-Neto

Publications and source records attributed to J Palermo-Neto.

At least 55 records · Page 3Linked to original sources

PubMed1995

Chemical and biological demonstration of the presence of monofluoroacetate in the leaves of Palicourea marcgravii St. Hil.

Cattle losses in Brazil have been attributed to Palicourea marcgravii St. Hil., a toxic plant for cattle. The crude extract from the leaves of P. marcgravii was successively fractionated using solvents with different polarities to determine whether monofluoroacetic acid and/or some other substance present in the leaves may be responsible for the acute symptoms caused by the plant. Authentic sodium monofluoroacetate (SMFA) was used for comparison. The only P. marcgravii fraction which induced seizures and death in intoxicated rats was water soluble. The signs and symptoms induced in the animals by the crude extract and water-soluble fraction were the same as induced by SMFA and included tonic seizures and other actions on the CNS. The dose-lethality and dose-latency to the 1st seizure curves constructed for the water-soluble fraction of the leaf extract (30-100 mg/kg) and SMFA (0.6-3.0 mg/kg) were parallel. Five animals per dose were used. The potency ratio of SMFA in relation to the water-soluble fraction of the leaf extract was 53.8 (dose-lethality curve) and 64.1 (dose-latency to the 1st seizure curve). The water-soluble fraction contained a substance with hRf = 20 which was the same as that of authentic SMFA. The 19F NMR spectra of authentic SMFA and the P. marcgravii water-soluble fraction were identical. These data demonstrate the presence of SMFA in the water-soluble fraction of P. marcgravii leaves and show that monofluoroacetate is the active principle responsible for the signs and symptoms of acute intoxication.

Animals↗

PubMed1994

Behavioral and neurochemical changes induced by aging in dopaminergic systems of male and female rats.

Changes induced by aging in dopaminergic activity of male and female rats were compared by behavioral and neurochemical methods. Young (3 months) and old (23 months) rats were used. Aging decreased animal activity in the open field and increased apomorphine-induced stereotyped behavior. No differences in open field data were observed between males and females. Young and aged female rats had higher striatal DA and HVA levels than males; aging induced a decrease in both striatal DA and HVA levels in males, but not in females. No changes in HVA/DA ratios were observed among the different groups. These results show that aging reduces nigrostriatal activity as well as nigrostriatal DA levels. Furthermore, they indicate that time course events related to aging differ between males and females.

Aging↗

PubMed1994

Acute 2,4-dichlorophenoxyacetic acid intoxication in cattle.

The acute toxicity of 2,4-dichlorophenoxyacetic acid (2,4-D) was studied in cattle. Steers were orally treated with 100, 300 or 600 mg 2,4-D/kg. Behavioral alterations, heart and respiratory functions, rectal temperature and ruminal movements were observed at 2, 4, 8, 12, 24, 48, 72 and 96 h after treatment. At these moments, blood and urine samples were collected and serum 2,4-D levels were determined. Results show that animals' vital function and hematocrit were not modified by the herbicide. Other signs were doses and time-dependent and included motor alterations (weakness, lethargy, decreased general activity) and decreased ruminal movements and proteinuria. The herbicide was rapidly excreted and the intoxication signs were completely reserved. 2,4-D is an herbicide of small toxicological consequences for cattle kept under in natural grazing systems.

2,4-Dichlorophenoxyacetic Acid↗

PubMed1994

Pro and anticonvulsant effects of xylazine on convulsion models in rodents.

Pretreatment of mice with 30 mg xylazine/kg ip protected against convulsions induced by amphetamine, but it intensified pentylenetetrazole- and strychnine-induced seizures. Xylazine pretreatment also protected rats against electroshock-induced convulsions. These findings support a noradrenergic mechanism being involved in the proconvulsant and/or anticonvulsant effects of xylazine.

Amphetamine↗

PubMed1994

Effects of acetamide on experimentally-induced Palicourea marcgravii (St Hill) poisoning in rats.

High indices of mortality in cattle have been reported in Brazil as a consequence of Palicourea marcgravii (Pm) acute intoxications. It has been established that Pm leaves contain monofluoroacetic acid (MFA), the active toxic principle of the plant. Rational therapy for MFA poisoning involves the use of a substance that might prevent fluorocitric acid formation. The present work was undertaken to verify if acetamide, a MFA antidote and an acetate donor, protects rats against both Pm and MFA intoxications. It was verified that acetamide protected rats from both convulsions and death. Future experiments should be carried out on cattle to examine the efficiency of acetamide, and particularly under field conditions.

Acetamides↗

PubMed1993

Effects of 2,4-dichlorophenoxyacetic acid (2,4-D) on open-field behaviour and neurochemical parameters of rats.

The effects of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) on the central nervous system (CNS) were studied in rats. Behavioural and neurochemical studies were performed. Results show that acute and oral administration of dimethylamine 2,4-D was able to decrease locomotion and rearing frequencies and to increase immobility duration of rats observed in an open-field test. Treatment of rats with p-chlorophenylalanine (PCPA) was unable to change rat's open-field behaviour; 5-hydroxytryptophan (5-HTP) administration not only increased locomotion and rearing frequencies but also decreased immobility duration. Pretreatment of the rats with PCPA and 5-HTP decreased and increased dimethylamine 2,4-D effects, respectively. The herbicide was not able to change the striatal levels of dopamine and homovanilic acid but decreased the striatal levels of serotonin (5-HT), as observed for the doses of 100 and 200 mg/kg and increased those of 5-hydroxyindoleacetic acid (5-HIAA) as measured after the 200 mg/kg dose treatment. When the levels of serotonin and 5-HIAA were measured at the brain stem level, only those of 5-HIAA were modified, being increased by diethylamine 2,4-D (60; 100 and 200 mg/kg); this increment on 5-HIAA levels was observed even 1 hr after pesticide administration. Further analysis showed that 2,4-D concentrations chromatographically detected both in serum and brain of the intoxicated animals were dose-dependent, being found as early as 1 hr after the smaller dose of the herbicide used (10 mg/kg). The results suggest that diethylamine 2,4-D modify 5-HT functional activity within the CNS.(ABSTRACT TRUNCATED AT 250 WORDS)

2,4-Dichlorophenoxyacetic Acid↗

PubMed1993

Effects of amitraz on motor function.

The effects of amitraz, a formamidine derivative, on motor function were studied in rats. Behavioural and neurochemical studies were performed. Results show that amitraz was able: 1) to decrease locomotion and rearing frequencies of rats and to increase their immobility time in an open-field; 2) to displace to the left the control dose-response curve constructed to apomorphine-induced stereotyped behavior; 3) to potentiate both pentobarbital sleeping time and amphetamine effects on open-field behaviour of rats and 4) to increase not only the whole brain levels of noradrenaline but also the striatal levels of dopamine. In relation to control animals, the pesticide also induced 5) a decrease in the striatal levels of homovanillic acid, 6) pesticide effects on open-field behaviour of rats were not antagonized by yohimbine administration, and 7) metoclopramide administration on amitraz pretreated rats antagonized not only amphetamine effects on open-field behaviour, but also apomorphine-induced stereotypy. These results are discussed in the light of the actions of amitraz on biogenic amines. It is suggested that the pesticide effects on motor function are consequences of the inhibitory effects on MAO activity, most probably through the increases produced on catecholamine levels within the central nervous system.

Amines↗

PubMed1992

Evaluation of prenatal aldrin intoxication in rats.

The aim of the present study was to evaluate the impact of prenatal exposure to low doses of aldrin on physical and behavioral developments of rats (1-21 days old). To detect the possible persistent adversities produced by this exposure, the animals were also tested when adults (90 days old). Plasma determinations of both aldrin and its metabolite dieldrin and histopathological evaluations of brain slices were also performed in adult animals. Pregnant female rats were subcutaneously (s.c.) treated with aldrin (1.0 mg/kg) or with its vehicle (0.9% NaCl solution plus Tween-80) from day 1 of pregnancy until delivery. Results show that prenatal aldrin administration was able to decrease the median effective time (TE50) for incisor teeth eruption and to increase the TE50 for testes descent; other parameters indicative of physical development were not modified. Aldrin and dieldrin were not found in plasma of the adult rats; no differences were observed between control and experimental rats in the cellular and structural organization of the cerebral cortex neurones. Prenatal aldrin administration produced no impairment of adult animal's behavior in an avoidance learning test; nevertheless, the locomotor frequency of the experimental rats was higher than that of controls at 21 and 90 days old. When adults, these experimental rats had their performance in a hole-board apparatus (total number and duration of head-dips) also higher than that of the control ones. It was concluded that prenatal aldrin exposure induced not only developmental changes in the rat pups but also persistent behavioral alterations in adulthood, when the pesticide was not present in these animals.

Aldrin↗

PubMed1992

Lithium effects on estrogen-induced dopaminergic supersensitivity in rats.

The effect of lithium (2.0 mEq/kg, IP) on dopaminergic supersensitivity induced by long-term estrogen treatment (0.25 mg/day, SC) was investigated. Ovariectomized rats were treated for 28 days with estrogen and/or lithium and 6 days after the last administration all animals were observed for apomorphine-induced stereotyped behavior (1.0 mg/kg, SC). The abrupt withdrawal from long-term estrogen treatment increased rats' sensitivity to apomorphine but lithium administration was able to prevent this increase. Lithium alone produced no effect on stereotyped behavior. It was suggested that lithium may antagonize the estrogen effect on the nigrostriatal dopamine system.

Animals↗

PubMed1992

Effects of age and isolation on the evolution of catalepsy during chronic haloperidol treatment.

Sixteen young (5 months) and 16 old (20-24 months) male Wistar rats, housed together or in individual cages were observed for cataleptic behavior 10, 20 and 30 days after the beginning of chronic haloperidol treatment (1.0 mg/kg, twice daily, for 30 days). Catalepsy was measured by the bar test. Age increased the duration of haloperidol-induced catalepsy of isolated and group-housed rats in the three observation sessions (old-isolated = 7.4 +/- 0.2; old-group housed = 7.5 +/- 0.1; young-isolated = 6.3 +/- 0.2; young-group housed = 6.8 +/- 0.2 In seconds in session 1, for example). Conversely, isolation did not modify the sensitivity to the cataleptic effect of haloperidol. Even more important, no differences in duration of haloperidol-induced catalepsy were observed among the three sessions for each group. The results indicate that under the experimental conditions employed the animals did not develop tolerance nor sensitization to haloperidol-induced catalepsy. In addition, neither age nor isolation modified the absence of effects of repeated haloperidol treatment on the catalepsy behavior of rats.

Aging↗

PubMed1991

Effects of single and long-term droperidol administration on open-field and stereotyped behavior of rats.

The effects of single and long-term droperidol administration on rat open-field and apomorphine-induced stereotyped behavior were studied. A single dose of droperidol decreased dose dependently not only locomotion and rearing frequencies in the open-field but also the apomorphine effects. Long-term droperidol administration induced significant tolerance to all parameters of activity recorded in the open-field. Unlike other dopamine blockers, droperidol withdrawn from long-term droperidol administration wasn't able to increase rats' open-field parameters significantly. However, like other dopamine blockers, droperidol withdrawn produced an augmented responsiveness to apomorphine-induced stereotyped behavior. These results suggest that the supersensitivity of central dopamine receptors developed after droperidol treatment may have peculiar characteristics.

Animals↗

PubMed1991

Effects of Croton zehntneri aqueous extracts on some cholinergic- and dopaminergic-related behaviours of laboratory rodents.

The effects of aqueous Croton zehntneri leaf and branch extracts, orally administered, on some dopaminergic- and cholinergic-related behaviours were studied in rats and mice. The leaf extract did not modify apomorphine-induced stereotypic behavior, haloperidol-induced catalepsy and active avoidance/escape responses. The branch extract reduced stereotypy but did not interfere with catalepsy and active avoidance behavior. Both extracts were capable of increasing the tremor induced by oxotremorine.

Animals↗

PubMed1991

Effects of acute 2,4-dichlorophenoxyacetic acid intoxication on some rat serum components and enzyme activities.

The present study was undertaken to investigate the effects of acute 2,4-dichlorophenoxyacetic acid (2,4-D) intoxication (0.6 g/kg, po) on lactate dehydrogenase, alkaline phosphatase, aspartate aminotransferase, alanine aminotransferase, amylase, creatinine, glucose, total protein and albumin levels in rats. Serum levels of lactate dehydrogenase, alkaline phosphatase and creatinine increased from 1- to 4-fold at 5, 8 and 24 h after 2,4-D administration, whereas serum levels of aspartate and alanine aminotransferase were higher only at 8 and 24 h. Amylase levels were only increased 8 h after administration of 2,4-D and then returned to normal levels. In contrast, 2,4-D reduced the serum levels of glucose and total protein 5, 8 and 24 h and serum albumin levels 5 h after herbicide intoxication. Thus, acute intoxication with 2,4-D disrupts serum levels of several enzymes and components which are considered to be indicators of tissue injury. Most likely these alterations mainly reflect hepatic and muscle tissue damage induced by the herbicide, but significant pancreatic and kidney toxicity may also have occurred.

2,4-Dichlorophenoxyacetic Acid↗

PubMed1990

Influences of estrogen and/or progesterone on some dopamine related behavior in rats.

1. The effects of ovariectomy and/or of female hormonal treatments on open-field behavior, apomorphine-induced stereotypies and haloperidol-induced catalepsy were studied in rats. 2. Rat's locomotion frequency was significantly decreased by 17 beta-estradiol and estradiol plus progesterone treatments; this open-field parameter was not affected by progesterone administration per se. 3. 17 beta-estradiol and progesterone treatments, alone or in combination decreased apomorphine-stereotyped behavior. 4. Haloperidol effects were higher in both 17 beta-estradiol and 17 beta-estradiol plus progesterone treated rats. 5. Progesterone treatment alone, decreased the duration of catalepsy induced by the minor (1.0 mg/kg) neuroleptic dose. 6. These results were discussed in the light of a possible interference of estrogen and/or progesterone on dopaminergic transmission at the level of the nigroestratial pathway.

Animals↗

PubMed1990

Effects of dihydroergotoxine on some dopamine-related behaviors in rats.

1. The effects of dihydroergotoxine on open-field behavior, apomorphine-induced stereotype and haloperidol-induced catalepsy were studied quantitatively in rats. 2. Dihydroergotoxine decreased the open-field behavior of rats, in a dose-dependent manner; this effect remained at least for 8 hr. 3. Dihydroergotoxine (10.0 mg/kg) caused a 1.40 leftward displacement of the dose-response curve constructed for apomorphine-induced stereotypy; the ED50 for apomorphine was reduced from 0.40 (+/- 0.05) to 0.29 (+/- 0.03). 4. Dihydroergotoxine (10.0 mg/kg) was unable to change haloperidol-induced catalepsy. 5. Results were discussed in the light of a possible interference of central noradrenergic systems with the expression of dopaminergic behaviors.

Animals↗

PubMed1990

Effects of a Palicourea marcgravii leaf extract on some dopamine-related behaviors of rats.

The effects of a Palicourea marcgravii leaf extract on some dopamine-related behaviors were studied in rats. The extract given subcutaneously decreased both spontaneous locomotion and rearing frequencies of rats observed in open-field studies and increased their periods of immobility. The extract was also able to produce a rightward displacement of the apomorphine dose-response curve for stereotyped behavior and decrease the maximum response possible. Although the extract (1.87 g/kg subcutaneously) was unable to produce true catalepsy by itself, it potentiated that induced by haloperidol. These results with the extract can be interpreted to be due to a direct blocking action for the extract on a mesostriatal dopamine receptor or to an indirect effect on dopamine pathways through central cholinergic activation.

Animals↗

PubMed1990

Effects of single and long-term administration of sulpiride on open-field and stereotyped behavior of rats.

1. The effects of single (3.0 to 180.0 mg/kg) and long-term (up to 90.0 mg/kg) administration of sulpiride on open-field and apomorphine-induced stereotyped behavior of rats were studied. 2. When animals were studied 30 min after ip sulpiride administration, locomotion and rearing frequencies in the open-field or apomorphine effects were not modified in a dose-dependent and consistent way by the single sulpiride administration. 3. In relation to control values, a significant decrease in apomorphine-induced stereotyped behavior was observed when rats were injected with a single sulpiride dose 2.5, 5.0, 7.5 and 10.0 h before the dopaminergic agonist. 4. Withdrawal from long-term ip sulpiride administration (up to 90.0 mg/kg per injection, twice daily for 57 days) induced a significant increase in all parameters of activity recorded in the open-field, and the responsiveness to apomorphine was also augmented in sulpiride-withdrawn rats. 5. These results suggest that sulpiride, a benzamide drug that differs from classic neuroleptic agents by producing fewer extrapyramidal side effects, also induces supersensitivity of central dopaminergic receptors.

Animals↗

PubMed1990

Effects of exposure to a pyrethroid insecticide during lactation on the behavior of infant and adult rats.

Cyhalothrin, a pyrethroid insecticide, was administered to female Wistar rats as a 0.02% solution plus 0.04% sucrose (w/v) in drinking water from whelping to pup weaning after 21 days of lactation. The pesticide did not change the maternal behavior of the dams as measured by the scoring system of Soderstein and Eneroth. The body weight of pups exposed to the pesticide and at age 90 days was not different from that of controls, and the motor activity of the pups measured in a simple photocell activity cage was not affected by pesticide treatment. Furthermore, no overt signs of neural toxicity were observed in the offspring. However, the treatment disrupted rat behavior in adulthood when assessed by using an inhibitory avoidance learning task. Thus, inhibitory avoidance tests carried out on rats at 90 days of age were capable of demonstrating neural toxicity of Cyhalothrin (0.02%) present only in the drinking water of dams during 21 days of lactation.

Animals↗