noradrenalin h 3 Animal 32 Rats 32 radioisotope 32 Norepinephrine 28 noradrenalin 28 rat 28 animal experiment 26 endocrine system 24 Male 22 Support, Non-U.S. Gov't 22 Female 18 In Vitro 18 central nervous system 18 Rats, Inbred Strains 16 article 16 in vitro study 16 Hypothalamus 14 autonomic nervous system 14 hypothalamus 14 pineal body 14 Pineal Gland 12 animal 12 metabolism 12 nonhuman 12 Castration 10 Ganglia, Sympathetic 10 estradiol 10 Arthropod Venoms 8 Black Widow Spider 8