Effect of immunization on nocturnal NAT activity in chicken pineal gland

OBJECTIVES: The effect of a single immunization with sheep red blood cells (SRBC) on the nocturnal NAT activity in the pineal gland and serum anti-SRBC agglutinin titer was examined in the young, sexually immature ASTRA S chickens. METHODS: 3-, 4-, and 5-week-old birds of both sexes, hatched in long (Spring) and short (Autumn) day, were housed from hatching in controlled light (L:D = 12:12) and temperature conditions. Quantity of produced 14C-labeled N-acetyltryptamine was used as a measure of the nocturnal NAT activity in the pineal gland. Serum anti-SRBC agglutinins were determined by microhemagglutination test. RESULTS: In experimental conditions applied, a sexual dimorphism in both pineal gland function and immune system activity was observed. NAT activity was dependent on the season, sex and age of chickens examined and was modified by the single immunization with SRBC. CONCLUSION: Results obtained confirmed once again the existence of the reciprocal functional connection between the pineal gland and immune system in chickens and demonstrated that even in well controlled experimental conditions the influence of the seasonal factor(s) on immunity must be taken into consideration.