Effect of optic chiasmotomy upon serotonin concentration in the pineal gland of the monkey

The concentration of serotonin within the pineal gland of the monkey exhibits a 24‐hour rhythm, being higher during the hours of light and falling during the hours of darkness. Chiasmotomies were performed upon male cynomolgus monkeys ( Macaca irus ) to ascertain whether the intrapineal concentration of serotonin is dependent upon information passing from the eyes by means of nerve fibers that cross in the optic chiasma. After two weeks, the operated animals, whether killed in the light or the dark, showed a significant reduction in intrapineal serotonin compared with controls; however, the concentration of serotonin in operated animals killed during hours of light was comparable with that of control animals killed during the corresponding hours of darkness. The results indicate that the intrapineal concentration of serotonin is dependent upon information transmitted from the eyes by means of nerve fibers which cross in the optic chiasma; it is possible that these fibers are also components of the accessory optic tracts. It also is suggested that during hours of light, uncrossed fibers of retinal origin may participate in the regulation of the intrapineal serotonin concentration of this monkey

Biology · Circadian rhythm · Darkness · Optic chiasma · Optic nerve · Pineal gland · Serotonergic · Serotonin · Anatomy · Endocrinology · Glaucoma and retinal disorders · Internal Medicine · Medicine · Retinal Development and Disorders · Visual perception and processing mechanisms