Steroid Binding at σ Receptors Suggests a Link Between Endocrine, Nervous, and Immune Systems

Abstract
Specific σ binding sites have been identified in the mammalian brain and lymphoid tissue. In this study, certain gonadal and adrenal steroids, particularly progesterone, were found to inhibit σ receptor binding in homogenates of brain and spleen. The findings suggest that steroids are naturally occurring ligands for σ receptors and raise the possibility that these sites mediate some aspects of steroid-induced mental disturbances and alterations in immune functions.