vasoactive-intestinal-peptide and mesotocin

Topics: Animals; Birds; Chickens; Corticotropin-Releasing Hormone; Enkephalin, Methionine; Glucagon; Gonadotropin-Releasing Hormone; Hormones; Hypothalamus; Median Eminence; Microscopy, Electron; Oxytocin; Pituitary Gland, Anterior; Pituitary Hormone-Releasing Hormones; Pituitary Hormones, Anterior; Somatostatin; Substance P; Vasoactive Intestinal Peptide; Vasotocin

The pars distalis of the avian adenohypophysis consists of well-defined cephalic and caudal lobes which are distinct in their cellular constituents. Immunocytochemical investigations on the pituitary hormones of the pars distalis of the Japanese quail reveal five types of secretory cells, adenocorticotropin (ACTH) cells, prolactin (PRL) cells, thyroid-stimulating hormone (TSH) cells, growth hormone GH (STH) cells, and FSH/LH (gonadotropic) cells. The ACTH cells, TSH cells, and PRL cells are restricted to the cephalic lobe, and GH (STH) cells are confined to the caudal lobe, while FSH/LH cells are distributed throughout the cephalic and caudal lobes. The median eminence of birds has distinct anterior and posterior divisions, each with different neuronal components. The avian hypophysial portal vessels also consists of two groups, anterior and posterior. The peculiar arrangement and distribution of the avian hypophysial portal vessels are possibly related to the distribution of neuropeptides in the two divisions of the median eminence and to the cytological and functional differentiation of two lobes of the pars distalis. The localization of perikarya and fibers containing luteinizing hormone releasing hormone (LHRH), somatostatin, vasotocin, mesotocin, corticotropin-releasing factor (CRF), vasoactive intestinal polypeptide (VIP), glucagon, metenkephalin, and substance P in the hypothalamus and median eminence of the Japanese quail has been investigated by means of immunohistochemistry using antisera against the respective neuropeptides. LHRH-, somatostatin-, VIP-, met-enkephalin-, and substance P-immunoreactive fibers are localized in the external layer of the anterior and posterior divisions of the median eminence, while CRF- and vasotocin-reactive fibers are demonstrated only in the external layer of the anterior division of the median eminence. The metenkephalin fibers are thicker in the anterior median eminence but the substance P fibers are more abundant in the posterior division. Mesotocin fibers occur only in the internal layer of the median eminence and neural lobe.

Topics: Adrenocorticotropic Hormone; Animals; Corticotropin-Releasing Hormone; Coturnix; Enkephalin, Methionine; Fluorescent Antibody Technique; Follicle Stimulating Hormone; Glucagon; Gonadotropin-Releasing Hormone; Growth Hormone; Histocytochemistry; Hypothalamus; Luteinizing Hormone; Nerve Tissue Proteins; Neurons; Oxytocin; Pituitary Gland, Anterior; Prolactin; Quail; Somatostatin; Substance P; Thyrotropin; Vasoactive Intestinal Peptide; Vasotocin

Previous research demonstrates that intraseptal administrations of arginine vasotocin (AVT) inhibit male aggression in the territorial field sparrow (Emberizidae: Spizella pusilla) but facilitate aggression in the colonial zebra finch (Estrildidae: Taeniopygia guttata). In order to determine whether this difference may be related to the territorial and colonial social organizations of these two species, the effect of AVT infusions was examined in a territorial Estrildid species, the violet-eared waxbill (Uraeginthus granatina). This species is more closely related to the zebra finch than to the field sparrow and shares most critical features of breeding ecology in common with zebra finches, but differs in social organization. AVT infusions administered via chronic guide cannulae directed at the septum significantly inhibited aggressive behavior, consistent with results in the territorial field sparrow, supporting the hypothesis that social organization is correlated with AVT function. Similar experiments with mesotocin and substance P produced no effects on any of the behaviors measured, but infusions of vasoactive intestinal polypeptide (VIP) significantly facilitated aggression. This result contrasts with the inhibitory effect of septal VIP obtained in the colonial zebra finch, suggesting that VIP function may be correlated with social organization as well.

Topics: Aggression; Animals; Birds; Female; Male; Oxytocin; Substance P; Vasoactive Intestinal Peptide; Vasotocin; Vocalization, Animal