Circadian variations in peripheral levels of growth hormone and testosterone in male Murrah buffaloes

Abstract

The aim of this study was to investigate the endocrine profiles of growth hormone (GH), testosterone and their interrelationship in prepubertal, pubertal and orchiectomised male Murrah buffaloes under starving conditions. The prepubertal and pubertal buffaloes were subjected to frequent blood sampling over 24 h at an interval of 1 h, whereas in orchiectomised buffaloes, the blood samples were collected over 18 h. Irrespective of group, the GH concentrations fluctuated in an episodic manner over 24 h and the fluctuations did not exhibit a consistent pattern between the animals of each group. The mean basal and peak concentrations of GH did not differ significantly (p > 0.05) among the groups. A significant (p > 0.0001) difference in testosterone concentrations was observed between prepubertal and pubertal groups. The differences in mean basal and peak testosterone concentrations between the prepubertal and pubertal groups were also significant (p < 0.01). The associations between testosterone and GH levels in both prepubertal (r = 0.15; p > 0.05) and pubertal (r = −0.37; p > 0.05) buffaloes were non-significant. The possible reasons for erratic episodic pattern of GH secretion will be discussed.

Keywords:

• Growth hormone
• male Murrah buffaloes
• orchiectomy
• testosterone

Acknowledgements

Financial support provided by the Director, NDRI, Karnal, India, and testosterone antisera gifted by Dr. GD Niswender, former Director, Colorado State University, and Fort Collins are greatly acknowledged.

Disclosure statement

No potential conflict of interest was reported by the authors.