The effect of exogenous growth hormone releasing hormone on the regulation of growth hormone in prepubertal and pubertal cats

• Main Authors: Sasisopa Singhanetr, 辛美月
• Other Authors: 李衛民
• Format: Others
• Language: en_US
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/05491134558868842317

碩士 === 國立中興大學 === 獸醫學系暨研究所 === 96 === Growth hormone releasing hormone (GHRH) is a hypothalamic peptides that stimulates GH secretion. Growth hormone (GH) is a major regulator of growth, somatic development and body composition; it is secreted in a pulsatile manner which is sexually dimorphic in most mammalian species, and affected by age, gender, body composition and so on. In this study, we aim to investigate the GH response to exogenous GHRH for determining pituitary functions in the cats (4 females, 4 males) in different age (5, 11, 17, and 21 months). Different doses of GHRH (1, 2, and 4 µg/kg) were infused intravenously in pubertal cats. The administration of 1 µg/kg GHRH did not result in the change of plasma GH level in both prepubertal and pubertal cats, as well as 2 and 4 µg/kg GHRH in pubertal cats, and there were no significant different in basal plasma GH level between male and female cats. Although the change of plasma IGF-1 level after GHRH administration was not observed, however, we found that pubertal female cats had significantly lower basal plasma IGF-1 level than prepubertal period (p<0.01), and male cats had significantly higher basal plasma IGF-1 level than female since prepubertal period (p<0.01). There were no glucose and cortisol response to GHRH observed as well. In conclusion, exogenous GHRH did not stimulate GH, IGF-1, glucose, and cortisol secretion in both prepubertal and pubertal cats. The present study suggest that plasma IGF-1 level of the cats were reducing by age, and the different of plasma IGF-1 level could be observed since prepubertal period.