Immune Modulation in Goats by Melatonin and Other Hormones: A Novel Horizon of Research

Goats are the primary producers of meat, milk and leather in the tropical and temperate countries from time unknown. In global as well as Indian economic scenario goats are regarded as “Poor man's Cow”. But, the management of immune system of this animal was neglected by the researchers for prolonged time. Immune system of the body of an individual is an open circuit and is being regulated by a number of hormones (gonadal steroids/ neurohormones/ metabolic hormones) and factors (cytokines, chemokines and lymphokines). Some of the hormones are having immune suppressive functions (particularly the gonadal steroids and cortisol/ corticosterone) or some of them are having neutral effect on immune modulation. Goats are ruminant short day breeders and their seasonality in terms of reproduction and immunity is under influence of melatonin. Melatonin is regarded as immunostimulator in most of the species having a direct correlation with interleukins (particularly with IL-2) in a paracrine manner it regulates immunity. Administration of exogenous hormones in vitro is an approach that can directly measure the effects of said hormone on immune cell proliferation. It also helps in understanding the cross-talk between the metabolic (thyroxin, cortisol), gonadal steroid (testosterone, estrogens) and circulatory cytokines (IL-2, IL-6, TNF-α, IFN-γ) with potent immunostimulator melatonin on isolated goat splenocytes and thymocytes. In the present review we elaborated the effects of different hormones in vivo and in vitro along with melatonin in a seasonal short day breeder i.e. goat.