Effects of aggressive encounters on pineal melatonin formation in male gerbils (Meriones unguiculatus, Cricetidae)

Th Heinzeller, B. N. Joshi, F. Nürnberger, R. J. Reiter

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


Pineal N-acetyl-transferase activity and radioimmunoassayable melatonin levels were determined in adult male gerbils subjected to aggressive encounters using the intruder-model. In the first experiment, a single encounter of 3 min was applied in the afternoon to intact and to animals with sympathetically denervated pineal organs. Compared with controls, both stressed groups demonstrated a drastic decrease in N-acetyl-transferase activity followed by a slow recovery. In both groups there also occurred a marked change in pineal melatonin content: in intact animals pineal melatonin levels were elevated immediately after the encounter; thereafter, melatonin values decreased. In animals bearing denervated pineal organs melatonin levels fell as a consequence of the encounter. In a second experiment, intact gerbils experienced four daily encounters of 1 min for one week. Thereafter the nocturnal formation of melatonin was studied. In comparison with untreated controls, the repeatedly stressed animals demonstrated a temporal delay in the rise of both N-acetyl-transferase activity and melatonin. Since the pineal organ is able to transduce events of the social environment into an endocrine message - as set forth by both our experiments - the pineal organ might play an important role within central processing of social stress.

Original languageEnglish (US)
Pages (from-to)91-94
Number of pages4
JournalJournal of Comparative Physiology A
Issue number1
StatePublished - Jan 1988
Externally publishedYes

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Physiology
  • Animal Science and Zoology
  • Behavioral Neuroscience


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