Effect of different diurnal lighting conditions on serotonin content in the pig pineal gland. Subcellular fractions of the tissue.

Serotonin content in the pineal glands and in their subcellular fractions of the pig housed under natural and limited to circa 2.5 hours per day lighting conditions has been examined spectrofluorometrically. The shortened circadian light phase caused dramatically high drop of serotonin content in the evening (1900-2000). Correlation between presence of dense bodies in subcellular fractions and content of serotonin has been not observed.