Characterization and Regulation of the Neonatal Growth Hormone Surge

Author(s)

Gusmao, Daniela O. ; de Sousa, Ligia M. M. ; de Sousa, Maria E. ; Rusew, Stephanie J. R. ; List, Edward O. ; Kopchick, John J. ; Gomes, Andre F. ; Campideli-Santana, Ana C. ; Szawka, Raphael E. ; Donato Jr, Jose

• Document type: Journal article
• Source: Endocrinology; v. 165, n. 12, p. 12-pg., 2024-11-08.

Abstract

High neonatal growth hormone (GH) secretion has been described in several species. However, the neuroendocrine mechanisms behind this surge remain unknown. Thus, the pattern of postnatal GH secretion was investigated in mice and rats. Blood GH levels were very high on postnatal day (P)1 and progressively decreased until near zero by P17 in C57BL/6 mice without sex differences. This pattern was similar to that observed in rats, except that female rats showed higher GH levels on P1 than males. In comparison, follicle-stimulating hormone exhibited higher secretion in females during the first 3 weeks of life. Hypothalamic Sst mRNA and somatostatin neuroendocrine terminals in the median eminence were higher in P20/P21 mice than in newborns. Knockout mice for GH-releasing hormone (GHRH) receptor showed no GH surge, whereas knockdown mice for the Sst gene displayed increased neonatal GH peak. Leptin deficiency caused only minor effects on early-life GH secretion. GH receptor ablation in neurons or the entire body did not affect neonatal GH secretion, but the subsequent reduction in blood GH levels was attenuated or prevented by these genetic manipulations, respectively. This phenotype was also observed in knockout mice for the insulin-like growth factor-1 (IGF-1) receptor in GHRH neurons. Moreover, glucose-induced hyperglycemia overstimulated GH secretion in neonatal mice. In conclusion, GH surge in the first days of life is not regulated by negative feedback loops. However, neonatal GH secretion requires GHRH receptor, and is modulated by somatostatin and blood glucose levels, suggesting that this surge is controlled by hypothalamic-pituitary communication. (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: 23/11833-5 - Physiological mechanisms that control GH secretion: identification of the pulse generator and events associated with somatotropic axis maturation
• Grantee: Lígia Maria Martins de Sousa
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 24/03067-3 - Role of somatostatinergic neurons of the extended amygdala in the control of food intake
• Grantee: Stephanie Junqueira dos Reis Rusew
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)
• 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