Pineal Hydroxyindole-O-Methyltransferase and Gonadal Responses to Blinding or Continuous Darkness Blocked by Pineal Denervation in the Male Hamster

Abstract

Denervation of the pineal by cervical sympathectomy is equivalent to pinealectomy in blocking the testicular atrophy caused by blinding or exposure of male hamsters to constant darkness. Ganglionectomy, or decentralization of the superior cervical ganglia, was found in this study to block the rise in activity of the pineal melatonin-forming enzyme, hydroxyindole-O-methyltransferase, and the testicular atrophy produced by blinding and constant darkness. These findings provide further evidence for the role or melatonin as a pineal hormone affecting gonadal function in the hamster.