Neuroimmunomodulation: potentiation of delayed hypersensitivity and antibody production by chronic electrical stimulation of the rat brain.

This study deals with the structural and functional correlates of the immunoneuroendocrine interconnections, and explores the effects of localized brain stimulation on immune response. Bilateral symmetrical electrodes were placed in the dorsomedial nucleus, ventromedial nucleus and posterior area of the hypothalamus, and in the sensorimotor cerebral cortex of the rat brain. Electrical stimulations were applied for 39 consecutive days, 10 days before and 29 days after single immunization. In sham-stimulated rats, electrodes were lowered into the hypothalamic areas and sensorimotor cortex without passing any current. Animals with electrodes were divided post mortem into groups according to the histological location of the electrode tips. Intact rats served as additional controls. All animals were immunized with bovine serum albumin in complete Freund's adjuvant and tested for immune reactions 7, 14, 21, and 28 days after immunization. The most significant finding was the potentiated delayed skin hypersensitivity and, to a lesser extent, antibody production to bovine serum albumin in rats with stimulated dorsomedial hypothalamus and sensorimotor cortex. On days 21 and 28, skin reactions increased in rats with stimulated posterior hypothalamus. These immune effects could not be obtained when the stimulation was applied to the hypothalamic ventromedial nucleus. Several pathways of the immunoneuroendocrine interplay are suggested.