title: Melatonin and differential effect of L-thyroxine on immune system of Indian tropical bird Perdicula asiatica.
abstract: Interaction of thyroxine and melatonin on immune status was noted in vivo and in vitro when peripheral melatonin was high and thyroxine low in plasma of male Perdicula asiatica during reproductively inactive phase. During this phase exogenous thyroxine (4 microg/100g. Bwt./day) and melatonin (25 microg/100g. Bwt./day) increased immune parameters (spleen weight, total leukocyte count, lymphocyte count, percent stimulation ratio) and increased splenocyte density in spleen. In vitro l-thyroxine (10(-6)M/ml) supplementation decreased the splenocyte proliferation which was reversed by melatonin (500 pg/ml) supplementation. In vivo l-thyroxine showed immunoenhancing effect while in vitro it decreased the splenocyte proliferation presenting a differential effect. In the absence of internal physiological conditions of the birds, T(4) showed a negative effect on splenocytes proliferation in vitro when treated alone. However, melatonin maintained its lymphoproliferative effect under both conditions. Thus, avian splenocyte exposed to different hormonal conditions in vitro might have produced different signal peptides other than in vivo, thereby making the result different.
authors.affiliation: Pineal Research Laboratory, Department of Zoology, Banaras Hindu University, Varanasi-221 005, India.
authors.forename: Shiv Shankar
authors.initials: SS
authors.lastname: Singh
authors.forename: Chandana
authors.initials: C
authors.lastname: Haldar
authors.forename: Seema
authors.initials: S
authors.lastname: Rai
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D003208:Concanavalin A / Q000494:pharmacology; D007107:Immune System / Q000187:drug effects*; D007958:Leukocyte Count; D008213:Lymphocyte Activation / Q000187:drug effects; D018655:Lymphocyte Count; D008214:Lymphocytes / Q000166:cytology / Q000187:drug effects; D008297:Male; D008550:Melatonin / Q000494:pharmacology*; D009929:Organ Size / Q000187:drug effects; D011784:Quail / Q000276:immunology*; D012098:Reproduction / Q000187:drug effects / Q000276:immunology; D013154:Spleen / Q000033:anatomy & histology / Q000166:cytology / Q000187:drug effects; D013974:Thyroxine / Q000494:pharmacology*
chemical_list: D000975:Antioxidants; D003208:Concanavalin A; D008550:Melatonin; D013974:Thyroxine