Long-term impairment of social memory in the rat after social defeat is not restored by desglycinamide-vasopressin

Repeated social defeat followed by individual housing caused a long-term im pairment of social memory in male rats. Social memory, as assessed in the s ocial discrimination test using an intertrial interval of 3 min, was impair ed for at least 8 weeks after the social defeat experience. Since social me mory of male rodents depends on proper functioning of the sexually dimorphi c vasopressin system, it was investigated whether a centrally active vasopr essin fragment could restore the impaired social memory. Subcutaneous admin istration of 6 mug/kg of the vasopressin fragment desglycinamide-vasopressi n (VP1-8) 40 days after social defeat slightly improved social memory in bo th control and socially defeated rats. It is concluded that social defeat f ollowed by individual housing caused a long-term impairment of social memor y, which was not restored by treatment with VP1-8. (C) 2001 Published by El sevier Science Ireland Ltd.