pituitrin and sauvagine

Neuroendocrine factors that produce species differences in aggregation behavior ("sociality") are largely unknown, although relevant studies should yield important insights into mechanisms of affiliation and social evolution. We here focused on five species in the avian family Estrildidae that differ selectively in their species-typical group sizes (all species are monogamous and occupy similar habitats). These include two highly gregarious species that independently evolved coloniality; two territorial species that independently evolved territoriality; and an intermediate, modestly gregarious species that is a sympatric congener of one of the territorial species. Using males and females of each species, we examined binding sites for (125)I-vasoactive intestinal polypeptide (VIP), (125)I-sauvagine (SG; a ligand for corticotropin releasing factor, CRF, receptors) and a linear (125)I-V(1a) vasopressin antagonist (to localize receptors for vasotocin, VT). VIP, CRF and VT are neuropeptides that influence stress, anxiety and/or various social behaviors. For numerous areas (particularly within the septal complex), binding densities in the territorial species differed significantly from binding in the more gregarious species, and in most of these cases, binding densities for the moderately gregarious species were either comparable to the two colonial species or were intermediate to the territorial and colonial species. Such patterns were observed for (125)I-VIP binding in the medial bed nucleus of the stria terminalis, medial septum, septohippocampal septum, and subpallial zones of the lateral septum; for (125)I-SG binding in the infundibular hypothalamus, and lateral and medial divisions of the ventromedial hypothalamus; and for the linear (125)I-V(1a) antagonist in the medial septum, and the pallial and subpallial zones of the caudal lateral septum. With the exception of (125)I-SG binding in the infundibular hypothalamus, binding densitites are positively related to sociality.

Topics: Amphibian Proteins; Animals; Autoradiography; Biological Evolution; Birds; Brain Chemistry; Corticotropin-Releasing Hormone; Female; Ligands; Male; Neuropeptides; Peptide Hormones; Peptides; Protein Binding; Receptors, Neuropeptide; Social Behavior; Species Specificity; Terminology as Topic; Territoriality; Vasoactive Intestinal Peptide; Vasopressins; Vasotocin

Corticotropin-releasing factor (CRF), sauvagine (SVG), and urotensin I (UI) were tested for their effects on superior mesenteric blood flow in conscious dogs. Intravenous (iv) administration of CRF, SVG, and UI induced an immediate rise of mesenteric blood flow that was associated with a decrease in mean arterial pressure and an increase in heart rate. Intracerebroventricular (ICV) injection of SVG and UI, but not CRF, rapidly (within 5 min after injection) elicited a long (90 min) elevation of mesenteric blood flow. Central administration of these peptides induced a delayed rise in heart rate and slightly elevated mean arterial pressure. The finding that CRF given ICV did not increase mesenteric blood flow could not be explained by the release of vasoactive agents such as vasopressin, epinephrine, or norepinephrine. After injection of CRF, SVG, and UI, plasma concentrations of CRF-, SVG-, and UI-like immunoreactivity did not increase as determined by radioimmunoassay. These results indicate that SVG and UI, but not CRF, administered ICV produce a long increase of mesenteric blood flow in conscious dogs. Because iv SVG and UI decrease mean arterial pressure and ICV SVG and UI increase mean arterial pressure and do not cause an increase in SVG- and UI-like immunoreactivity in the peripheral circulation, it is proposed that SVG and UI injected into the third cerebral ventricle act within the central nervous system to increase superior mesenteric blood flow in the dog.

Topics: Amphibian Proteins; Animals; Blood Pressure; Brain; Corticotropin-Releasing Hormone; Diuresis; Dogs; Epinephrine; Heart Rate; Injections, Intraventricular; Male; Norepinephrine; Peptide Hormones; Peptides; Radioimmunoassay; Splanchnic Circulation; Time Factors; Urotensins; Vasopressins

The biological activity of partially purified bovine hypothalamic CRF (corticotrophin- releasing factor) was compared to those of synthetic CRFs (ovine, rat) sauvagine and vasopressin in vivo and in vitro. ACTH-primed hypophysectomized rats with heterotopically transplanted pituitaries and medial basal hypothalamic ablation (H-T + MBHA ), and intact rats pre-treated with chlorpromazine, morphine and Nembutal (C-M-N) were used for in vivo CRF assays. Perifused rat adenohypophyseal fragments were employed for in vitro studies. CRF-A (void volume fractions, 'big' CRF) and CRF-B (Kav = 0.583) purified from bovine hypophyseal stalk, synthetic ovine and rat CRF, and sauvagine all induced significant stimulation of ACTH and/or corticosterone secretion in these systems. Synthetic ovine and rat CRF and sauvagine showed comparable CRF potency. The CRF dose-response slopes for bovine CRF were somewhat steeper than those for ovine CRF or sauvagine in the in vitro system. Vasopressin had the least steep dose-response slope. Intravenous bolus administration of ovine CRF caused a more prolonged (greater than 20 min) elevation of plasma ACTH compared to a relatively short duration after bovine CRF-A. These data suggest that bovine hypothalamus contains substance(s) which exhibits different CRF characteristics from those of ovine CRF.

Topics: Adrenocorticotropic Hormone; Amphibian Proteins; Animals; Cattle; Corticosterone; Corticotropin-Releasing Hormone; Dose-Response Relationship, Drug; Female; Hypophysectomy; Hypothalamo-Hypophyseal System; Male; Peptide Hormones; Peptides; Rats; Rats, Inbred Strains; Sheep; Species Specificity; Vasopressins

Topics: Adrenocorticotropic Hormone; Amino Acid Sequence; Amphibian Proteins; Animals; Corticotropin-Releasing Hormone; Gonadotropin-Releasing Hormone; Humans; Melanocyte-Stimulating Hormones; Peptide Hormones; Peptides; Thyrotropin-Releasing Hormone; Vasodilator Agents; Vasopressins