“…In cattle luteinizing hormone (LH) is released in a pulsatile pattern (Williams et al, 1987;Roberson et al, 1989;Kojima et al, 2003) that depends on age, reproductive stage of the estrous cycle, pregnancy and post-partum (Roberson et al, 1989;Nakada et al, 2002) and effects of other factors, i.e., leptin, naloxone (an opiate antagonist), neuropeptide-Y (Zieba et al, 2003;Kadokawa et al, 2006;Stahringer et al, 1990;Thomas et al, 1999;Ahmadzadeh et al, 1998). Hypophysial stalk transection of prepuberal beef heifer calves results in complete inhibition of episodic LH secretion compared with that seen in sham-operated controls .…”