Orexin system in buffalo ovarian follicles and effect of orexin on oestradiol production

Abstract

The orexins A and B, also known as hypocretin A and B, are excitatory hypothalamic neuropeptide hormones produced by the cleavage of a single precursor protein prepro-orexin (PPO), consisting of 131 amino acids. Orexin-A and -B were discovered simultaneously in 1998 by two independent laboratories (De Lecea et al., 1998;Sakurai et al., 1998). Orexin-A (OXA) is a 33-amino acid peptide, while orexin-B (OXB) consists of 28 amino acids. The amino acid sequence of OXA is highly conserved among mammalian species, including rats, pigs, cows, and humans, and the sequence of OXB in pigs and humans varies by only one amino acid residue (Sakurai