In Vivo Effects of TRH, T₃ and cGH on Antibody Production and T- and B-Lymphocytes Proliferation in Immature Male Chickens

Abstract

Newly hatched White Leghorn male chicks were used in this study. Different doses of T₃ (O.1 or 1 ppm) or TRH (1 or 5 ppm) were administered in the feed for an 8-week period. Chicken growth hormone (cGH) (10 μg/kg BW) was injected (i.v.) into a different group of chicks twice daily for 1 week starting at 7 weeks of age. A different group received both T₃ (0.1 and 1 ppm) and cGH. Serum concentrations of T₄, T₃ and GH, antibody production against sheep red blood cells (SRBC) and Brucella Abortus (BA), and in vitro proliferative response of both T- and B-lymphocytes to mitogenic stimulation were measured. Supplementation of T₃ (1 ppm) significantly lowered T₄ and increased T₃ concentrations. No effect of any hormone treatment on antibody production was observed. T₃ supplementation and cGH injection alone or with T₃ (0.1 ppm) significantly increased blastogenic response of lymphocytes to either Con-A or LPS mitogenic stimulation. It was concluded that T₃ and GH are involved in lymphocyte activity of chickens.