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The major non-psychoactive compound of cannabis plant, cannabidiol, has been reported to be a promising therapeutic agent for many inflammatory, autoimmune and neurodegenerative diseases. In spite of growing interest in therapeutic use of cannabidiol very little is known about its influence on the immune system. Present study aimed to evaluate lymphocyte subsets distribution in peripheral blood after repeated, systemic administration of cannabidiol. Adult male Wistar rats received intraperitoneal injections of vehicle or cannabidiol at dose of 2.5 or 5 mg/kg/day, for 14 consecutive days. Blood samples were collected one hour after the last injection. Three-color immunofluorescent antibody staining procedure (CD3-FITC/CD45RA-PC7/CD161A-APC and CD3-FITC/CD4-PC7/CD8-APC) was used for determination of T, B, NK, NKT, T helper, and T cytotoxic lymphocyte subsets. Total leukocyte number and percentage numbers of leukocyte subpopulations were also assessed. Administration of cannabidiol at dose of 5 mg/kg caused a significant decrease in total leukocyte number and a significant fall in total numbers of T, B, and both T helper and T cytotoxic lymphocyte subsets. This immunosuppressive effect did not affect the total numbers of NK and NKT cells that are responsible for the primary, nonspecific antiviral and antitumor immune response. In contrast, administration of cannabidiol at dose of 2.5 mg/kg increased the total and percentage NKT cells numbers, and the percentage number of NK cells. The results suggest that repeated treatment with cannabidiol inhibits specific immunity by reduction of T, B, T cytotoxic, and T helper cell numbers, and may enhance nonspecific antiviral and antitumor immune response related to NK and NKT cells.

Food intake is regulated not only by homeostatic requirements but also by emotional factors (e.g. palatability of food, alleviation of emotional tension etc.). The nucleus accumbens (Acb) is a part of the mesolimbic dopaminergic system which is responsible for a positive emotional aspect of various homeostasis-relevant stimuli. In the present work, we tested the Acb involvement in feeding behaviour using an experimental paradigm specifically designed to assess motivational vs motor aspect of food ingestion. In rats, feeding was evoked by electrical stimulation of the midbrain ventral tegmental area (a somatodendritic region of mesolimbic system) and assessed quantitatively with the use of the latency to feed/stimulation frequency curve-shift paradigm before and after electrolytic lesion of Acb. An impairment of stimulation-induced feeding manifesting as an elevation of the reaction threshold and a rightward, parallel shift of the stimulation frequency/reaction latency curve in the range of frequency which is sensitive to motivational aspects of food occurred after lesions localized mainly in the Acb shell. The lesions situated mainly in the Acb core were ineffective. The results obtained indicate that the Acb shell connected with the limbic system but not the motor-related Acb core affects motivational aspects of feeding behaviour.