Immune responses in nucleus basalis magnocellularis-lesioned rats exposed to chronic isolation stress

The present study was designed to establish the influence of chronic social isolation stress on humoral and cellular immunity in nucleus basalis magnocellularis (NBM)-lesioned rats. Therefore, ten days after bilateral electrolytic lesions of NBM, adult male Wistar rats were immunized with bovine serum albumin in complete Freund's adjuvant (BSA-CFA) and placed individually or in groups of five rats during 21 days. On days 10 and 21 after immunization, the Arthus and delayed hypersensitivity skin reactions to BSA as well as anti-BSA antibody production were determined. On day 10, the diameter and intensity of delayed hypersensitivity skin reaction to BSA were significantly higher in social-isolated rats in comparison with the group-reared ones. On day 21, the diameter and intensity of the Arthus skin reaction were significantly higher in social-isolated rats compared to group-reared rats. Between days 10 and 21, the diameter and intensity of the Arthus skin reaction significantly increased in social-isolated rats, while the diameter of delayed hypersensitivity skin reaction significantly decreased. In contrast to social-isolated rats, there were no significant differences in Arthus and delayed hypersensitivity skin reactions in group-reared rats, between days 10 and 21. Also there were no significant differences in the production of anti-BSA antibody between social-isolated and group-reared rats. The relative spleen weight was significantly lower in social-isolated rats. These data suggest that chronic isolation stress modify humoral and cellular immunity in NBM-lesioned rats.