The long-term effect of serotonin on the thermoregulatory behavior in juvenile cyprinidae (Cyprinus carpio and Carassius auratus)

The effect of serotonin after intracerebroventricular (ICV) injections in dosage of 0.3 and 0.15 μg/g of the body weight on the thermoregulatory behavior in juvenile carp Cyprinus carpio L. and goldfish Carassius auratus (L.) has been studied in two experiments of 10- to 11-day duration. It has been found that ICV injection of serotonin in dosage of 0.3 μg/g caused the initial decrease in preferred temperatures (PT) (2–3 days) followed by their further increase (4–8 days after the administration) in carp. ICV injection of serotonin in dosage of 0.15 μg/g caused more durable initial decrease in PT (2–8 days) followed by the increase of once (9–11 days of observation) in goldfish. The values of the ultimate preferred temperature in fish of the experimental group exceeded that in control specimens by 4.1 °C at the first experiment and by 3.1 °C in the second experiment. The data for the first time demonstrated long-term effect of a single ICV injection of serotonin on the thermoregulatory behavior in two closely related species of teleosts.