Functions of the Sensory Circumventricular Organs

Abstract

The morphology, neural connectivity, neurochemistry and modified barrier properties of the sensory CVOs dealt with in the preceding sections are guideposts to the functions that these regions of the CNS subserve. Investigations over the past 30 years have greatly enriched our understanding of why these CVOs are built the way they are and what their physiological and pathophysiological roles may be. High on the list are sensory functions related to body fluid regulation and cardiovascular control, but clearly the sensory CVOs may also have other important roles such as that of the area postrema in vomiting and the participation of the sensory CVOs in fever. Neurosecretion into the circulation may also be a function, particularly in regard to the OVLT, where LHRH-containing neurons may release this peptide into the bloodstream (Samson et al. 1980), possibly in a cyclic manner (Wenger and Leonardelli 1980; Wenger et al. 1981; Piva et al. 1982). There is no evidence of a portal secretion from the OVLT to the anterior pituitary, and the target for this LHRH released from the OVLT is unknown (Lescure et al. 1978). In this final section we review sensory functions of the CVOs.