Failure to stimulate melatonin synthesis in the rat pineal gland with an adenosine analog

Maurizio Nordio, Domenico Conte, Keico O. Nonaka, Russel J. Reiter, Aldo Isidori

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


Recent studies indicate the presence of adenosine binding sites in rat pinealocytes and an effect of their activation on pineal serotonin metabolism. However, controversial data exist, and reports suggest that the role of adenosine in pineal physiology is complex. On this basis, we evaluated the effects of an adenosine analog (N-ethyl-carboxamido-adenosine: NECA) on in vitro and in vivo melatonin production in the rat pineal gland. In the in vitro protocol, pineals were incubated with NECA (0.5 mM, 1 mM, or 2.5 mM) or isoproterenol (ISO: 10-6 M) for 4 hr. In the in vivo experiments, animals were given NECA (1 mg/kg IP), ISO (0.5 mg/kg IP) or 1 ml saline diluent and sacrificed 2 hr later. The samples were assayed for pineal N-acetyltransferase (NAT) activity and melatonin concentrations. ISO caused the expected marked rise in NAT activity and melatonin levels in both protocols. NECA was ineffective in causing any modification of the parameters measured. We conclude that the adenosine analog NECA may not be involved in the activation of melatonin production. These data contrast with others in which NECA administration resulted in an increase in an increase in melatonin levels. The participation, if any, of the purinergic system in the physiology of the pineal gland is still far from being characterized.

Original languageEnglish (US)
Pages (from-to)249-254
Number of pages6
Issue number2-3
StatePublished - 1992
Externally publishedYes

ASJC Scopus subject areas

  • Endocrine and Autonomic Systems
  • Psychiatry and Mental health
  • Biological Psychiatry
  • Endocrinology
  • Endocrinology, Diabetes and Metabolism


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