Fasting and prolonged food restriction differentially affect GH secretion independently of GH receptor signaling in AgRP neurons

Author(s)

de Sousa, Maria E. ; Gusmao, Daniela O. ; dos Santos, Willian O. ; Moriya, Henrique T. ; de Lima, Felipe F. ; List, Edward O. ; Kopchick, John J. ; Donato Jr, Jose

• Document type: Journal article
• Source: Journal of Neuroendocrinology; v. N/A, p. 14-pg., 2023-03-25.

Abstract

Growth hormone (GH) receptor (GHR) is abundantly expressed in neurons that co-release the agouti-related protein (AgRP) and neuropeptide Y (NPY) in the arcuate nucleus of the hypothalamus (ARH). Since ARH(AgRP/NPY) neurons regulate several hypothalamic-pituitary-endocrine axes, this neuronal population possibly modulates GH secretion via a negative feedback loop, particularly during food restriction, when ARH(AgRP/NPY) neurons are highly active. The present study aims to determine the importance of GHR signaling in ARH(AgRP/NPY) neurons on the pattern of GH secretion in fed and food-deprived male mice. Additionally, we compared the effect of two distinct situations of food deprivation: 16 h of fasting or four days of food restriction (40% of usual food intake). Overnight fasting strongly suppressed both basal and pulsatile GH secretion. Animals lacking GHR in ARH(AgRP/NPY) neurons (AgRP?GHR mice) did not exhibit differences in GH secretion either in the fed or fasted state, compared to control mice. In contrast, four days of food restriction increased GH pulse frequency, basal GH secretion, and pulse irregularity/complexity (measured by sample entropy), whereas pulsatile GH secretion was not affected in both control and AgRP?GHR mice. Hypothalamic Ghrh mRNA levels were unaffected by fasting or food restriction, but Sst expression increased in acutely fasted mice, but decreased after prolonged food restriction in both control and AgRP?GHR mice. Our findings indicate that short-term fasting and prolonged food restriction differentially affect the pattern of GH secretion, independently of GHR signaling in ARH(AgRP/NPY) neurons. (AU)

• FAPESP's process: 21/03316-5 - Evaluation of the importance of GABAergic and dopaminergic transmission in neurons that express the growth hormone-releasing hormone to the control of GH secretion
• Grantee: Daniela de Oliveira Gusmão
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 20/01318-8 - Central nervous system as a target of growth hormone for the regulation of multiple biological functions
• Grantee: Jose Donato Junior
• Support Opportunities: Research Projects - Thematic Grants