Immunoregulation by the neurohypophysis

Abstract

The role of the neurohypophysial hormones on immunoregulation has not been completely elucidated. To obtain a deeper insight, groups of Lewis rats were subjected to sham operation (SHAM), anterior (AL) or neurointermediate pituitary lobectomy (NIL) or total hypophysectomy (HYPX) and immunized for adjuvant induced arthritis (AIA) or experimental autoimmune encephalomyelitis (EAE). Intact control groups were included for reference. Groups were sacrificed 15 days postimmunization. Serum levels of PRL, ACTH and AVP, and spleenic ILs mRNA expression and macrophages number were assessed. In the AIA experiment, SHAM animals showed normal PRL, ACTH and AVP serum levels, increased expression of ILs 1 and 12, no changes in the remaining ILs, and significant increase in macrophages number. In the AL rats, normal AVP and low PRL and ACTH serum levels occurred. Except TNFα, ILs‐1,‐2,‐6,‐10,‐12, INFγ and macrophages number were significantly increased. In NIL rats, low AVP and normal PRL and ACTH levels occurred, and no alterations in ILs expression and macrophages number were found. In HYPX animals, low PRL, ACTH and AVP were apparent, while ILs‐1 and ‐12 and macrophages number were significantly increased. In general, similar results were obtained in EAE groups. The results indicate that immune responses can occur in absence of the pituitary gland and that AVP is an important immunoregulator.Supported by UAA and CONACYT. México