J. Palermo Neto

Effects of single and long-term haloperidol administration on open field behavior of rats

The effects of single and long-term haloperidol administration on rat open field behavior was studied. Withdrawal from long-term haloperidol treatment induced a significant increase in all parameters of activity recorded, expcept rearing. There was a direct relationship between the impairment of motor function induced by the single haloperidol administration and the increment of general activity observed after withdrawal from repeated drug administration. The results were considered to be a consequence of the supersensitivity of central dopaminergic receptors probably, of the mesostriatal pathway, that occurred in order to maintain the animals homeostasis.

Effects of abrupt and gradual withdrawal from long-term haloperidol treatment on open field behavior of rats

The effects of abrupt and gradual withdrawal from long-term haloperidol treatment on rat open field behavior was studied. Abrupt withdrawal induced a significant increase in all parameters of activity observed except defecation, this increase being higher 72 h after the last haloperidol injection. Results were considered to be a consequence of supersensitivity of central dopaminergic receptors. These differences were almost unobservable in animals gradually withdrawn, thus suggesting that the phenomenon is reversible.

The effects of chronic cannabis treatment on the aggressive behavior and brain 5-hydroxytryptamine levels of rats with different temperaments.

The effects of cannabis extract on aggressive behavior and whole and regional brain 5-HT levels were studied in rats selected for differences in temperament. The results indicated that rats with a high index of defection (HI) appeared to be more susceptible to the cannabis elicited aggressive behavior than the animals with a low index of defecation (LI). The defecation score expressed by the number of boluses and the ambulation score were counted in a series of open-field experiments. After chronic treatment with cannabis the 5-HT whole brain levels remained unchanged in the non-aggressive rats of both LI and HI group whereas the 5-HT levels fell down to about 50% of normal levels in the whole brain of aggressive animals. The greatest regional reductions in 5-HT were found in the cerebral hemispheres, midbrain and hypothalamus, although 5-HT levels remained unchanged in cerebellum and medula oblongata. This paper presents evidence suggesting that temperament may be an important factor involved in the ability of cannabis to induce aggressive behavior in starved rats, and that some basic brain mechanism probably differs in HI and LI rats. This difference could be responsible for the small aggressive response observed in LI rats after chronic treatment with cannabis.

The effects of chronic cannabis treatment upon brain 5-hydroxytryptamine, plasma corticosterone and aggressive behavior in female rats with different hormonal status

Ovariectomized rats, chronically treated with cannabis extract or control solution, were given different hormonal treatments. Results indicated that both cannabistreated and estrogen-treated animals were more aggressive than controls. Furthermore, aggressiveness was virtually abolished when cannabis-treated females were made sexually receptive by estrogen and progesterone treatments. After 25 days of cannabis or control solution treatment, all subjects were sacrificed. The levels and turnover rate of brain 5-HT and peripheral plasma corticosterone were then assayed. Data indicated both a significant inverse relationship between plasma corticosterone and whole brain levels of 5-HT (r=−0.742 to −0.985) for all groups and a significant positive relationship between aggressive behavior and plasma corticosterone (r=+0.675 to +0.946) in all groups that were fighting prior to decapitation. Results are tentatively explained, suggesting that the variability of the female response to stress during the different phases of the estrus cycle, permitted them to perform differently after chronic cannabis treatment. 5-HT is apparently involved, either directly in its effects on aggressive behavior or indirectly through the pituitary-adrenocortical axis activation.

The effects of diphenylhydantoin on rat behavior

Animals were administered increasing doses of diphenylhydantoin (DPH) for 20 days. During withdrawal they were observed in an open field. The results suggest that chronic DPH administration leads to a central supersensitivity phenomenon. Possible interference of DPH with dopaminergic systems was discussed.

Dexamethasone Regulates Macrophage and Cd4+Cd25+ Cell Numbers in the Chicken Spleen

Dexamethasone (DEX) is a corticoid hormone that is experimentally used to mimic the effects of increased levels of endogenous corticosterone observed during the stress response. Currently, stress is considered one of the major predisposing factors for diseases in the poultry industry. The aim of this study was to analyze the effects of DEX and/or of a 20-fold coccidial vaccine dose on leukocyte phenotypes in the spleen and cecal tonsils of chickens. Twenty specific-pathogen-free (SPF) Leghorn chickens were divided into four groups: a non-treated group (NT), a DEX-treated group (Dex), a vaccinated group (V) and a DEX-treated+vaccinated group (Dex+V). On experimental day (ED) 42, each bird in the vaccinated groups received a anti-coccidial vaccine. DEX was injected in the birds of the Dex and Dex+V groups (0.9 mg/kg) onED42 and ED45. The immunophenotyping was performed by flow cytometry analysis of splenocytes and cecal tonsils cells onED48. DEX treatment per se was unable to change CD4+CD8+, CD4+CD8+ and CD4-CD8+ populations with TCRgd or CD28 in the spleen, or macrophages and T lymphocytes in the cecal tonsils. V group birds presented higher numbers of splenic macrophages compared with those measured in the Dex+V group. The number of CD4+CD25+ cells in the spleen of birds of the V group was higher than those measured in the other experimental groups. Our data suggest that CD4+CD25+ cells and macrophages might be influenced by DEX treatment in spleen, but not in the cecal tonsils of chickens inoculated with Eimeria.

Effects of anti-acetylcholine drugs on aggressive behaviour induced by Cannabis sativa in REM sleep-deprived rats

Cannabis sativa extracts (CE) and (-)-A9-trans-tetrahydrocannabinol( A9-THC) induce aggressive behaviour in paired rats previously deprived of rapid eye movement (REM) sleep (Alves, Goyos & Carlini, 1973; Carlini, 1977). We have examined the influence of pretreatment with anti-acetylcholine drugs on agressive behaviour induced by CE in REM sleep-deprived rats. Genetically similar female Wistar rats, after weaning at 30 days, were randomly housed in pairs in wire cages (16 x 30 x 18crn) at 22 ! C lo, on a non-reversed 12-h-light cycle, animals were 90 days old at the beginning of the experiments and had free access to food and water. CE was suspended in 0.9% NaCl + Tween-80 (Carlini & Kramer, 1965). Analysis of the CE showed it to contain 68 % of AO-THC, 5 % of cannabinol and 1 % of cannabidiol. Experiments were replicated seven times. All rats in each replication were REM-deprived three times, with an intersession period of 16 days, during which they were kept in pairs in their home cages. In each session REM sleep-deprivation was performed according to Alves & others (1973). After 96 h of REM deprivation, the animals were removed from the 6 c m platforms in water containers in fixed numerical order and returned to their homc cages. About 10 min after the end of each of the three sessions of REM-deprivation all rats were injected with a dose of CE(20mgkg-’, i.p.) and were observed for aggressive behaviour for 100 min. This dose of CE had previously produced more than 2 x lo3 s of fighting in all pairs of R E M sleep-deprived rats tested. 1 h before the end of REM-deprivation of both 2nd and 3rd sessions antiacetylcholine pretreatment was given. This consisted of intraperitoneal injections of atropine sulphate (25, 50, 100 mg kg-l), scopolamine hydrobromide (10,20 mg kg-’ or atropine methyl nitrate (50 mg kg-I). All dosages refer to the salt, and all drugs were dissolved in distilled water. Controls received only the vehicle (1 .O ml kg-I). The same pretreatment was given in both the 2nd and 3rd sessions within a group. Aggressive behaviour was recorded in seconds by two different observers as described by (Palermo Neto, Nunes & Carvalho, 1975). This criterion is very objective since highly positive correlations (r = +0492 to +0.965) were found between the scores from the two observers. To minimize possible effects of circadian changes that could interfere with the results, the experiments were designed to allow all subjects to be observed at the same time of the day, i.e., a t 9.30a.m. The results were analysed using the Mann-Whitney U one-tailed test for differences in duration of aggressiveness among the several groups. Differences were considered significant when P < 0.05. * Correspondence. 3-