Thyrotropin-releasing hormone in lamprey central nervous system

Abstract

Thyrotropin-releasing hormone (TRH) levels were measured by radioimmunoassay in the CNS of larval and adult sea lampreys and adult river lampreys. In larval sea lampreys, the pituitary complex contained approx. 609 pg TRH/mg, brain contained 43.5 ± 5.5 pg/mg (mean ± S.E.M.). while the spinal cord contained 11.2 ± 2.3 pg/mg. Corresponding levels in the adult sea and river lampreys were similar. Complete spinal transection did not significantly alter TRH levels below the lesion. Thus, the spinal cord contains TRH independent of supraspinal axonal projections.