Effect of sildenafil citrate on behavior and excitatory and inhibitory amino acids levels in albino rat's brain

Sildenafil is an active cGMP-specific phosphodiesterase type 5 inhibitor that is effective in the treatment of male erectile dysfunction. None of the previous studies have measured sildenafil or its possibly related neurochemical changes, but mainly they related their finding to sildenafil associated behavior changes. In this work, behavioral and brain neurochemical changes [excitatory and inhibitory neurotransmitters] associated with acute administration of sildenafil using male albino rats were investigated. Rats were divided into three groups [n=6]; group1 received saline [1ml/kg], group 2 received single doses of sildenafil [1.5mg/kg], while group 3 received single doses of sildenafil [100mg/kg]. Administration was via the intraperitoneal route. Behavior scores using EPM and brain homogenate for neurotransmitters evaluation by HPLC were carried out 60min after administration. Sildenafil did not produce any changes in behavior using the EPM test; also it did not alter the brain levels of excitatory, inhibitory and dopamine. Sildenafil produced dose dependent decreases in plasma dopamine level by mechanism[s] needs more neurochemical investigation. The chronic effect of sildenafil should be taken into consideration.

Pyridoxine effect on the antidepressant action of imipramine in albino mice

To evaluate the behavioral effect of pyridoxine on the antidepressant action of imipramine. Male Wistar albino mice of weights 25-35gms were used. Two experiments were carried out; the first on the acute effect of pyridoxine on the duration of immobility, and the second on the sub-chronic effects of pyridoxine alone and in combination with imipramine. In the first experiment, 4 groups of animals received saline, 65, 125, and 250mg/kg pyridoxine. Forced swimming test [FST] was performed 30 minutes after drug administration. In the second experiment, 6 groups of mice were used. The first group received saline, the second group received imipramine 10 mg/kg, the third group received pyridoxine 65mg/kg, the fourth group received pyridoxine 250mg/kg, the fifth group received combined treatment of imipramine and pyridoxine 65 mg/kg, while the sixth group received a combined treatment of imipramine and pyridoxine 250 mg/kg. Administration of drugs was at 24, 5, and one hour before the test. This work was carried out in the Biotechnology Research Center, Twisha, Libya, in June 2007. Acute administration of pyridoxine did not change the duration of immobility compared to the control group. Sub-chronic administration showed that pyridoxine [65mg/kg] did not change the immobility time, while a higher dose of pyridoxine [250mg/kg] decreased the immobility time. Imipramine at 10mg/kg reduces the immobility time significantly. Pyridoxine did not change imipramine action. Pyridoxine alone may produce an antidepressant effect. Pyridoxine in combination with imipramine did not change the imipramine action