Reproductive phase dependent effects of dietary L-tryptophan on biochemical constituents of pineal gland in male Indian palm squirrel, Funambulus pennanti.

Tryptophan serves as the substrate for the synthesis of various hydroxy- and methoxyindoles in the pineal gland. In the present study L-tryptophan (L-Trp; 0.5 mg/animal/day) was given in drinking water to male Indian Palm Squirrel for 30 days during reproductive active and pineal inactive phase (April) as well as during reproductive inactive and pineal active phase (December). During reproductive active phase serotonin (5-HT) content of pineal gland increased while accessory sex organ's weight decreased without affecting testes weight. During reproductive inactive phase all the biochemical constituents (protein, cholesterol and serotonin) of pineal gland decreased while testes and accessory sex organ's weight increased. This indicates a reproductive phase dependent effect of L-Trp on the biochemistry of pineal gland including 5-HT synthesis/release which in turn (via melatonin) manipulates reproductive functions of this rodent.