Comparative evaluation of the effect of L-Arginine and L-Homoarginine supplementation on reproductive physiology in ewes

Abstract

L-Arginine (LA) is a well-known amino acid involved in vital physiological processes. However, the physiological function of its methylated form known as L-Homoarginine (LHA), is not well understood. The aim of this study was to study the comparative effects of LA and LHA treatment on selected metabolites and parameters of reproductive physiology in non-pregnant ewes. Twelve Deccani ewes were selected and randomly distributed into 3 groups: Control, LA treated group and LHA group. Blood samples were collected for the evaluation of blood indices and hormone levels. Overall, nitrite, ovary weight, surface follicle number, estrogen, insulin like growth factor-1 (IGF-1), vascular endothelial growth factor (VEGF) showed an increase in the LA and LHA treated animals. On the other side, the levels of progesterone, inteleukin-1 beta (IL-1β), IL-6, tumor necrosis factor-alpha (TNF-α) were found to be decreased in LA and LHA group. Ovary size was not affected by LA and LHA treatment groups. In comparison with LA, the ovary weight, surface follicle number, estrogen levels and IL-6 expression were higher in LHA treated animals. The expression of VEGF indicated improved angiogenesis in the treated animals. Further, the expression of heat shock protein-27 (HSP-27) and HSP-70 were differentially modulated by LA and LHA. This data reinforces the beneficial role of LA and its metabolites LHA on the ovarian physiology and functionality and also reveals the potent role of LHA as an alternative to LA treatment in enhancing the reproductive ability in non-pregnant ewes.