pineal body Pineal Gland 82 Rats 72 Animal 70 rat 70 endocrine system 66 animal experiment 62 radioisotope 58 Support, Non-U.S. Gov't 56 central nervous system 56 Male 50 Rats, Inbred Strains 46 nonhuman 44 melatonin 38 Female 36 Norepinephrine 32 Melatonin 30 autonomic nervous system 30 noradrenalin 30 superior cervical ganglion 30 Ganglia, Sympathetic 24 Pineal gland 24 pineal gland 24 article 22 estradiol 22 in vitro study 22 Animals 20 Kinetics 20 animal cell 20 nervous system 18