Influence of thyroid status on TRH metabolism in rat olfactory bulb.
The effect of thyroid hormones (TH) on the metabolism of thyrotropin-releasing hormone (TRH) in the olfactory bulb (OB) was compared with the hypothalamic response to TRH. Two methods were used to induce hypothyroidism: propylthiouracyl-methimazole (PTU-M) or 131I treatment. Hyperthyroidism was produced by 3,3',5-triiodo-L-thyronine (T3) injections to the hypothyroid animals. With PTU-M treatment, paraventricular TRH mRNA levels increased 57% and returned to the euthyroid level with T3 treatment. In OB, TRH mRNA was not altered. The TRH content was unaffected in the mediobasal hypothalamus of PTU-M-treated animals whereas it was reduced in OB (31%) with no further response upon T3 treatment. 131I-induced hypothyroidism did not modify the OB TRH content but it was decreased (31%) in hyperthyroids. In the median eminence, TRH increased 26% in hypothyroids, and the response was reversed with T3. Our results demonstrate that treatments that change thyroid status can alter TRH levels in the OB, probably at a translational or postranslational level, though the effects may be pharmacological.
Uribe
R M
RM
Departamento de Bioquímica, Universidad Nacional Autónoma de México, Cuernavaca, Mor.
Joseph-Bravo
P
P
Ponce
G
G
Cisneros
M
M
Aceves
C
C
Charli
J L
JL
D000818:Animals; D007030:Hypothalamo-Hypophyseal System / Q000187:drug effects / Q000378:metabolism*; D007037:Hypothyroidism / Q000378:metabolism*; D008297:Male; D008713:Methimazole / Q000494:pharmacology; D009830:Olfactory Bulb / Q000187:drug effects / Q000378:metabolism*; D010286:Paraventricular Hypothalamic Nucleus / Q000187:drug effects / Q000378:metabolism*; D010903:Pituitary Gland, Anterior / Q000187:drug effects / Q000378:metabolism*; D011441:Propylthiouracil / Q000494:pharmacology; D014176:Protein Biosynthesis; D011499:Protein Processing, Post-Translational; D051381:Rats; D017208:Rats, Wistar; D013963:Thyroid Hormones / Q000494:pharmacology; D013973:Thyrotropin-Releasing Hormone / Q000378:metabolism*
D013963:Thyroid Hormones; D008713:Methimazole; D013973:Thyrotropin-Releasing Hormone; D011441:Propylthiouracil