The mechanism underlying the central glucagon-induced hyperglycemia and anorexia in chicks.
We investigated the mechanism underlying central glucagon-induced hyperglycemia and anorexia in chicks. Male 8-day-old chicks (Gallus gallus) were used in all experiments. Intracerebroventricular administration of glucagon in chicks induced hyperglycemia and anorexia from 30 min after administration. However, the plasma insulin level did not increase until 90 min after glucagon administration, suggesting that glucose-stimulated insulin secretion from pancreatic beta cells may be suppressed by central glucagon. The plasma corticosterone concentration significantly increased from 30 min to 120 min after administration, suggesting that central glucagon activates the hypothalamic pituitary adrenal (HPA) axis in chicks. However, central administration of corticotropin-releasing factor (CRF), which activates the HPA axis in chicken hypothalamus, significantly reduced not only food intake but also plasma glucose concentration, suggesting that CRF and the activation of the HPA axis are related to the glucagon-induced anorexia but not hyperglycemia in chicks. Phentolamine, an α-adrenergic receptor antagonist, significantly attenuated the glucagon-induced hyperglycemia, suggesting that glucagon induced hyperglycemia at least partly via α-adrenergic neural pathway. Co-administration of phentolamine and α-helical CRF, a CRF receptor antagonist, significantly attenuated glucagon-induced hyperglycemia and anorexia. It is therefore likely that central administration of glucagon suppresses food intake at least partly via CRF-induced anorexigenic pathway in chicks.
Graduate School of Agricultural Sciences, Kobe University, Kobe 657-8501, Japan. honda@tiger.kobe-u.ac.jp
Kazuhisa
K
Honda
Hiroshi
H
Kamisoyama
Taku
T
Uemura
Takashi
T
Yanagi
Noboru
N
Saito
Yohei
Y
Kurose
Kunio
K
Sugahara
Kazuo
K
Katoh
Shin
S
Hasegawa
D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000818:Animals; D001069:Appetite Regulation; D001786:Blood Glucose; D002645:Chickens / Q000378:metabolism / Q000502:physiology*; D003345:Corticosterone / Q000097:blood; D003346:Corticotropin-Releasing Hormone / Q000494:pharmacology; D002149:Energy Intake; D005934:Glucagon / Q000008:administration & dosage / Q000502:physiology*; D006727:Hormone Antagonists / Q000494:pharmacology; D007328:Insulin / Q000097:blood; D008297:Male; D010446:Peptide Fragments / Q000494:pharmacology; D010646:Phentolamine / Q000494:pharmacology
D000317:Adrenergic alpha-Antagonists; D001786:Blood Glucose; D006727:Hormone Antagonists; D007328:Insulin; D010446:Peptide Fragments; D005934:Glucagon; D003346:Corticotropin-Releasing Hormone; C045089:corticotropin releasing hormone (9-41); D003345:Corticosterone; D010646:Phentolamine