Antidepressant-like effect of nitric oxide synthase inhibitors and sildenafil against lipopolysaccharide-induced depressive-like behavior in mice.

Inflammation, oxidative and nitrosative stress underlie depression being assessed in rodents by the systemic administration of lipopolysacharide (LPS). There is an increasing body of evidence of an involvement of nitric oxide (NO) pathway in depression, but this issue was not investigated in LPS-induced model. Thus, herein we evaluated the effects of NO-pathway-modulating drugs, named aminoguanidine, l-NAME, sildenafil and l-arginine, on the behavioral (forced swimming test [FST], sucrose preference [SPT] and prepulse inhibition [PPI] of the startle) and neurochemical (glutathione [GSH], lipid peroxidation, IL-1ß) alterations in the prefrontal cortex, hippocampus and striatum as well as in BDNF levels in the hippocampus 24h after LPS (0.5mg/kg, i.p.) administration, a time-point related to depressive-like behavior. Twenty-four hours post LPS there was an increase in immobility time in the FST, decrease in sucrose preference and PPI levels accompanied by a decrease in GSH levels and an increase in lipid peroxidation, IL-1ß and hippocampal BDNF levels suggestive of a depressive-like state. The pretreatment with the NOS inhibitors, l-NAME and aminoguanidine as well as sildenafil prevented the behavioral and neurochemical alterations induced by LPS, although sildenafil and l-NAME were not able to prevent the increase in hippocampal BDNF levels induced by LPS. The iNOS inhibitor, aminoguanidine, and imipramine prevented all behavioral and neurochemical alterations induced by LPS. l-arginine did not prevent the alterations in immobility time, sucrose preference and GSH induced by LPS. Taken together our results show that the NO-cGMP pathway is important in the modulation of the depressive-like alterations induced by LPS.

Central nervous system activity of yangambin from Ocotea duckei Vattimo (Lauraceae) in mice.

This work presents behavioral effects of yangambin isolated from the leaves of Ocotea duckei on open field, rota rod, barbiturate sleeping time, forced swimming and elevated plus maze test in mice. Yangambin was intraperitoneally administered to male mice at single doses of 12.5, 25 and 50 mg/kg. The results showed that yangambin in the doses of 25 and 50 mg/kg decreased the locomotor activity and the number of rearing. However, no change was observed in the rota rod test between the yangambin groups as compared to the control group. Reduction on the sleep latency and a prolongation of the sleeping time induced by pentobarbital was observed only with the yangambin dose of 50 mg/kg. In the forced swimming test, yangambin (25 and 50 mg/kg) increased the immobility time. Yangambin, in the doses of 25 and 50 mg/kg, decreased the number of entries and the time of permanence in the open arms of the elevated plus maze test. However, this effect can not be related to anxiogenic effects, but to a decrease in locomotor activity. The results showed that yangambin presents a depressant activity in the open field, forced swimming and pentobarbital sleeping time tests. These effects probably were not due to peripheral neuromuscular blockade, since there was no alteration on the rota rod test. Also, no anxiolytic effect was observed after the treatment with yangambin.