Distribution and variation of neuropeptide Y in the brain of native Thai chicken

Neuropeptide Y (NPY) plays a pivotal role in food intake and body weight regulation in both birds and mammals. Unlike imported broilers and layers, native Thai chicken, a tropical non-seasonal breeding species, has lower body weight and exhibits strongly maternal behaviors which, in turn, affect feeding behavior during the reproductive cycle. The aim of this study was to investigate the role(s) of NPY that might be associated with the reproductive cycle of female native Thai chickens using immunohistochemistry technique. The distributions of NPY-immunoreactive (-ir) neurons and fibers in the brain of laying and fasted chickens was also elucidated. Changes in body weight and number of NPY-ir neurons in the nucleus paraventricularis magnocellularis (PVN) were compared across reproductive stages. The results revealed that NPY-ir neurons and fibers were distributed throughout the brain with the greatest density located in the PVN. Differences in the number of NPY-ir neurons in the PVN were found across reproductive stages. The numbers were lowest in non-egg laying and egg laying stages and significantly higher during egg-incubating and chick-rearing stages. Changes in body weight were inversely related to the number of NPY-ir neurons across reproductive stages. In addition, food restriction caused an increase in NPY immunoreactivity, confirming the role of NPY in response to food restriction. Taken together, the present findings suggest that the NPYergic system in the PVN plays an important role in the regulation of food intake during the reproductive cycle in this non-seasonal breeding tropical species.

Acute hypothalamo-pituitary-adrenal axis response to LPS-induced endotoxemia: expression pattern of kinin type B1 and B2 receptors

Bradykinin (BK) and des-Arg9-BK are pro-inflammatory mediators acting via B2 (B2R) and B1 (B1R) receptors, respectively. We investigated the role of B2R and B1R in lipopolysaccharide (LPS)-induced hypothalamo-pituitary-adrenal (HPA) axis activation in SD rats. LPS given intraperitoneally (ip) up-regulated B1R mRNA in the hypothalamus, both B1R and B2R were up-regulated in pituitary and adrenal glands. Receptor localization was performed using immunofluorescence staining. B1R was localized in the endothelial cells, nucleus supraopticus (SON), adenohypophysis and adrenal cortex. B2R was localized nucleus paraventricularis (PVN) and SON, pituitary and adrenal medulla. Blockade of B1R prior to LPS further increased ACTH release and blockade of B1R 1 h after LPS decreased its release. In addition, we evaluated if blockade of central kinin receptors influence the LPS-induced stimulation of hypothalamic neurons. Blockade of both B1R and B2R reduced the LPS-induced c-Fos immunoreactivity in the hypothalamus. Our data demonstrate that a single injection of LPS induced a differential expression pattern of kinin B1R and B2R in the HPA axis. The tissue specific cellular localization of these receptors indicates that they may play a crucial role in the maintenance of body homeostasis during endotoxemia.