CYCLIC VARIATIONS IN SPINAL CORD LEVELS OF OXYTOCIN AND VASOPRESSIN DURING THE STAGES OF THE RAT ESTROUS CYCLE

Publisher Website
Google Scholar
Abstract
Oxytocin (OT) and vasopressin (VP) have been localized to numerous central nervous system locations outside the classic hypothalamo-neurohypophyseal tract including all levels of the spinal cord. To date, the physiological function of these peptides within the spinal cord is unknown. The purpose of this study was to determine if the variations exhibited by pituitary OT and VP during the stages of the estrous cycle in the rat were also present in the spinal cord. The stages of the estrous cycle was determined by vaginal smears in female Long Evans rats. Following decapitation, the cervical, thoracic, and lumbosacral segments of the spinal cord were isolated and homogenized, and the hormones were extracted from the tissue with the Sep-pak method. OT and VP content were determined by RIA. A cyclic variation in spinal cord OT and VP was present, with maximal levels occurring in diestrus, a time in the estrous cycle when LH and estradiol levels are lowest. Our results suggest that spinal cord OT and VP may be regulated by ovarian hormones. There data represent the first documented changes in spinal cord levels of OT and VP under physiological conditions.