Elevated daytime rat pineal and serum melatonin levels induced by isoproterenol are depressed by swimming

Wutain Wu, Russel J. Reiter, Marueen E. Troiani, George M. Vaughan

Research output: Contribution to journalArticlepeer-review

22 Scopus citations


Isoproterenol (1 mg/kg) was subcutaneously injected into adult male rats during the day to stimulate pineal N-acetyltransferase (NAT) activity and pineal and serum melatonin levels. Two hours after isoproterenol administration when levels of each of these variables had increased significantly, the experimental animals swam for 10 min in 22°C water. At 15 min after swimming onset, pineal and serum melatonin levels were highly significantly depressed compared to those in control animals that did not swim. The high NAT level was not influenced by swimming. In a second study, isoproterenol injected rats swam for either 1, 3, 6 or 10 min and were sampled 15 min after the onset of swimming. The reduction in the elevated pineal melatonin in these animals was correlated with the length of the swim, i.e., as the duration of swim increased the percent reduction in pineal melatonin also increased. Neither pineal NAT nor hydroxyindole-O-methyltransferase (HIOMT) activities were influenced by swimming. The results suggest that elevated pineal and serum melatonin induced by isoproterenol can be depressed with no effect on the activity of the enzymes which convert serotonin to melatonin.

Original languageEnglish (US)
Pages (from-to)1473-1479
Number of pages7
JournalLife Sciences
Issue number12
StatePublished - Sep 21 1987

ASJC Scopus subject areas

  • General Pharmacology, Toxicology and Pharmaceutics
  • General Biochemistry, Genetics and Molecular Biology


Dive into the research topics of 'Elevated daytime rat pineal and serum melatonin levels induced by isoproterenol are depressed by swimming'. Together they form a unique fingerprint.

Cite this