FMRF-NH2-LIKE PEPTIDE IS DEFICIENT IN THE PITUITARY-GLAND OF THE BRATTLEBORO RAT

Phe-Leu-Phe-Gln-Pro-Gln-Arg-Phe-NH2 (F-8-F-NH2), isolated from bovine brain, is an FMRF-NH2-like peptide with morphine-modulating activity. In the rat, F-8-F-NH2 immunoreactivity (IR) is highly localized in the neurohypophysis. In this study, F-8-F-NH2-IR was studied in the hypothalamo-neurohypophyseal system of an Arg8-vasopressin (AVP)-deficient animal, the Brattleboro (DI) rat, and the normal control Long-Evans (LE) strain. F-8-F-NH2-IR in the DI pituitary is below the level of detection in contrast to that in the LE (0.50±0.04 pmol/gland). Neuropeptide Y (NPY) levels are increased two-fold in the DI pituitary while AVP levels are below detection. The content of F-8-F-NH2-IR in the hypothalami and spinal cords of DI and LE rats is not statistically different, suggesting that the absence of F-8-F-NH2-IR in the Brattleboro pituitary is not due to a genetic defect in F-8-F-NH2 biosynthesis. The results of this study raise the question whether AVP could be involved in the regulation of F-8-F-NH2 immunoreactivity in the neurohypophysis. © 1990.