ABSTRACT
Objective: To investigate the effect of Cannabis sativa extract on the development of neuro- and hepato-toxicity caused by malathion injection in rats. Methods: The extract of Cannabis sativa was obtained from the plant resin by chloroform treatment. Δ-Tetrahydrocannabinol content of the extract (20%) was quantified using gas chromatography-mass spectrometry. The doses of cannabis extract were expressed as Δ -tetrahydrocannabinol content of 10 or 20 mg/kg. Malathion (150 mg/kg) was intraperitoneally administered followed after 30 min by the cannabis extract (10 or 20 mg/kg, subcutaneously). Rats were euthanized 4 h later. Malondialdehyde (MDA), reduced glutathione (GSH), nitric oxide and paraoxonase-1 (PON-1) activity were determined in brain and liver. Brain 5-lipoxygenase and butyrylcholinesterase (BChE) activity were measured as well. Histopathological examination of brain and liver tissue was also performed. Results: Compared to controls, malathion resulted in increased oxidative stress in brain and liver. MDA and nitric oxide concentrations were significantly increased (P<0.05) and GSH significantly decreased with respect to control levels (P<0.05). Malathion also significantly inhibited PON-1 and BChE activities but had no effect on brain 5-lipoxygenase. Brain MDA concentrations were not altered by cannabis treatment. Cannabis at 20 mg/kg, however, caused significant increase in nitric oxide and restored the GSH and PON-1 activity. Brain BChE activity significantly decreased by 26.1% (P<0.05) after treatment with 10 mg/kg cannabis. Cannabis showed no effect on brain 5-lipoxygenase. On the other hand, rats treated with cannabis exhibited significantly higher levels of liver MDA, nitric oxide and PON-1 activity compared with the malathion control group. Rats treated with only malathion exhibited spongiform changes, neuronal damage in the cerebral cortex and degeneration of some Purkinje cells in the cerebellum. There were also hepatic vacuolar degeneration and dilated and congested portal vein. These histopthological changes induced by malathion in brain and liver were reduced to great extent by cannabis administration at 20 mg/kg. Conclusions: Our data suggest that acute treatment with cannabis alleviates the malathion-induced brain and hepatic injury in rats possibly by maintaining the levels of GSH and PON-1 activity.
ABSTRACT
In this study, we investigated whether alpha2-adrenoceptors are involved in the antinociception induced by different classes of antidepressant drugs using the acetic acid-induced writhing test in mice. The subcutaneous [s.c.] administration of the non-selective noradrenaline and serotonin rcuptake inhibitors; imipramine and amitriptyline; the selective 5-hydroxytryptamine [serotonin] reuptake inhibitors [SSRJs]; fluoxetine and sertraline and the heterocyclic agent; trazodonc caused dose-related decrease in the number of abdominal constrictions [writhings] caused by intraperitoneal [i.p.] injection of dilute acetic acid in mice. The acute analgesia induced by amitriptyline, sertraline and trazodone was blocked by co-administration of the alpha2-adrenoceptor antagonist yohirnbine [4 or 8 mg/kg]. In contrast, alpha-2 blockade enhanced imipramine-induced an1inociception. Meanwhile, yohimbine administration at 4 mg/kg bu1 not 8 mg/kg significantly reduced the fluoxetine-induced analgesia. These data suggest that alpha2-adrenoceptors mediate the analgesic effect of some antidepressant drugs independent of their effect on neurotransmitter release. The present data also suggest that distinct routes mediate the analgesic effect of individual agents within the same class of antidepressant drugs