Hypothalamic-pituitary-go nad al (HPG) axis and its functional regulation in birds

Reproductive physiology and behavior of birds aregoverned by the neuroendocrine regulation of the Hypothalamic-Pituitary-Gonadal (HPG)-axis. Hypothalamic neurons integrate internal and external signals to initiate the synthesis and secretion of gonadotropin-releasing hormone (GnRH), which marks the activation of the neuroendocrine pathway. GnRH mediated adeno-hypophysial gonadotropin stimulate the production of sex steroids and gonadal development. The entire process is strictly regulated by several external as well as internal factors. Present reviewgives information on the significance of HPG-axis in birds, along with the role of various internal and external factors on HPG-axis that helps in the regulation of reproduction in birds.