Neuropeptide FF in the Rat Adrenal Gland: Presence, Distribution and Pharmacological Effects

Abstract

Neuropeptide FF (NPFF, FLFQPQRFamide) is an FMRFamide-like octapeptide exhibiting antiopiate activity. The presence of both NPFF-immunoreactivity (NPFF-IR) and NPFF-specific receptors has been described in the mammalian central nervous system (CNS). The peripheral effects of NPFF indicate that NPFF-IR material is present outside the CNS. Biochemical and immunohistochemical methods enabled us to determine the presence and distribution of NPFF-IR in the rat adrenal gland. The amount of NPFF-IR material in whole gland was estimated by radioimmunoassay to be 19.00 +/- 4.00 fmol/gland. High performance liquid chromatography analysis of adrenal extracts revealed a single molecular form which coeluted with authentic NPFF. Demedullation decreased adrenal NPFF-IR content, indicating that NPFF-IR was present in both cortex and medulla. Light microscopy revealed NPFF-IR in beaded fibers confined in the outer part of the cortex and in medullary cells. Double-labeling with antityrosine-hydroxylase and anti-NPFF antibodies showed NPFF-IR in cortical catecholaminergic postganglionic fibers restricted to the subcapsular and glomerulosa zonae. NPFF-IR was also located in medullary chromaffin cells and in rays and islets of chromaffin cells dispersed throughout the cortex. Insulin-induced hypoglycemia did not alter NPFF-IR content. Denervation lowered adrenal NPFF-IR content. These data indicate that this peptide is present in nerve fibers of extrinsic origin. In vitro approaches using adrenal slices have shown that NPFF inhibited aldosterone release in a dose-dependent manner. Taken together, these data suggest that NPFF may participate in the control of aldosterone production and adrenal blood supply.

Identification of a Novel Prothoracicostatic Hormone and Its Receptor in the Silkworm Bombyx mori

“…Vertebrates including humans have also been shown to possess peptides with an RFamide C terminus (39,40), and at least one RFamide peptide has been shown to inhibit steroid hormone release in experiments using an in vitro adrenal slice culture system (41). Considering the conservation of RFamide peptides throughout metazoans, our result also indicates that RFamide peptides modulate steroid hormone secretion in various kinds of species, thereby controlling their postembryonic development.…”

A New Peptidic Ligand and Its Receptor Regulating Adrenal Function in Rats

“…Enkephalins reportedly have regulatory functions in the release of catecholamine from the medulla of the adrenal gland. In addition, neuropeptide FF exists in the adrenal gland and inhibits aldosterone release (27). Considering these results, RFamide peptides might play roles in the regulation of adrenal functions.…”

Identification of 26RFa, a hypothalamic neuropeptide of the RFamide peptide family with orexigenic activity

“…These two neuropeptides modulate the action of morphine (6) and are thus thought to be involved in the transmission of pain stimuli. However, NPFF is probably implicated in other physiological processes, such as regulation of energy homeostasis (7), arterial blood pressure (8), and hormone secretion (9,10). A second RFRP gene encodes the precursor for prolactin-releasing peptide (PrRP), which has been originally identified as the endogenous ligand of the orphan G protein-coupled receptor hGR3 (11).…”