Neurobehavioral effects of alcohol in overcrowded male adolescent rats

Being a critical neurodevelopmental stage that is affected by social conditions, the period of adolescence was chosen as the age of examining possible modification of alcohol neurobehavioral effects by overcrowding. Adolescent male rats (postnatal day 35 +/- 1) were subjected to overcrowding and/or injected with ethanol, 2 g/kg, 20% w/v, (i.p.) for one week. 24 h after the last dose, motor, exploratory behavior, sociability and fear responses were assessed using open field, social interaction and defensive probe burying tests, respectively. Wet brain tissue nitric oxide and reduced glutathione contents as well as monoamine levels, namely dopamine, norepinephrine and serotonin, in addition to 5-HIAA were estimated. Overcrowding increased social play and freezing time. Alcohol administration under overcrowding condition impaired sociability and interfered with active fear response. Alcohol in normal or in under overcrowding condition, impaired motor and exploratory behavior and increased anxiety. These results indicate that concomitant exposure of male adolescent rats to overcrowding and alcohol induced adverse behavioral changes.