Immunocytochemical detection of effects of TRH and T4 on prolactin- and TSH-producing cells in the pituitary gland of Rana ridibunda.
Effects of synthetic thyrotropin-releasing hormone (TRH) and various doses of thyroxin (T4) on prolactin (PRL)-producing cells and thyrotropic cells in the pituitary were investigated in adult male and female Rana ridibunda frogs. Animals were given 200 microg TRH once a week for 4 weeks and 0.2-0.5 mg T4 during 3 days per week for a period of 2 weeks by injections in the groin. PRL-producing cells and thyrotropic cells were identified with light microscopical and electron microscopical immunocytochemical methods, using rabbit anti-PRL and rabbit anti-thyroid stimulating hormone (TSH) as primary antibodies. TRH caused cytological changes in both cell types, which were consistent with increased synthesis and release of both PRL and TSH. Treatment with 0.5 mg T4 activated both cell types less than TRH treatment did, whereas 0.2 and 0.4 mg T4 caused inactivation of both cell types. In conclusion, mammalian TRH is effective on both types of frog pituitary cells. Our study suggests that T4 has a positive rather than a negative effect when concentrations above a certain threshold are given.
Akgün-Dar
Kadriye
K
Istanbul University, Faculty of Science, Department of Biology, Zoology Section, Vezneciler, 34459 Istanbul, Turkey. ezgi_hazal@hotmail.com
Erensoy
Nevin
N
Yilmazer
Selma
S
D000818:Animals; D004305:Dose-Response Relationship, Drug; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D007124:Immunoenzyme Techniques; D008297:Male; D016253:Microscopy, Immunoelectron; D010903:Pituitary Gland, Anterior / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D011388:Prolactin / Q000378:metabolism*; D011895:Rana ridibunda; D013972:Thyrotropin / Q000378:metabolism*; D013973:Thyrotropin-Releasing Hormone / Q000494:pharmacology*; D013974:Thyroxine / Q000494:pharmacology*
D013973:Thyrotropin-Releasing Hormone; D011388:Prolactin; D013972:Thyrotropin; D013974:Thyroxine