Anxiolytic-like actions of melatonin, 5-metoxytryptophol, 5-hydroxytryptophol and benzodiazepines on a conflict procedure

1. Male Wistar rats(120-230 g) were used in these experiments.: Some rats were deprived of water for 48 h before testing in a conflict procedure. Then, after 20 licks from a water bottle with a metal drinking tube, the animal received an electric shock (0.5 mA/500 msec). 2. The effects of two classical anxiolytic drugs, DIAZ (1.0, 2.0 and 40 mg/Kg b.wt), and CDP (5.0 and 10.0 mg/Kg b.wt) were compared to those produced by MEL (0.1, 0.2, 0.5, 1.0 and 2.0 mg/Kg b.wt), 5-MTOPHOL (1.0 and 2.0 mg/Kg b.wt), 5-HTOPROL (1.0 and 2.0 mg/Kg b.wt) and vehicle solution. 3. Anxiolytic drugs as well as MEL produced a dose-dependent increase in the number of shocks received. 4. The results suggest that the three pineal indoles are involved in the modulation of the stress responses. MEL showed a higher potency than the other indoles.