Effect of thyrotropin-releasing hormone (TRH) on plasma glucocorticoids and thyroxine in cattle.
The repeated systemic infusion of TRH (200 mug, twice daily) was effective in repeatedly elevating plasma T4 levels (20-40 min postinfusion) for the 3 experimental days. The post-TRH treatment (saline infusion) exhibited a depression of plasma thyroxine levels, possibly explained by previous high thyroxine levels exerting a suppressive effect on the hypothalamic-pituitary-thyroid axis. A depression of plasma glucocorticoid levels was shown within 1 hr in both experiments after TRH administration. The results indicate that TRH administration (systemic) is effective in temporarily elevating thyroxine levels and simultaneously lowering plasma glucocorticoids in cattle.
D000818:Animals; D002417:Cattle / Q000097:blood*; D005260:Female; D005938:Glucocorticoids / Q000097:blood*; D006361:Heating; D006813:Humidity; D007263:Infusions, Parenteral; D007601:Jugular Veins; D012965:Sodium Chloride / Q000008:administration & dosage; D013973:Thyrotropin-Releasing Hormone / Q000008:administration & dosage / Q000494:pharmacology*; D013974:Thyroxine / Q000097:blood*; D013997:Time Factors
D005938:Glucocorticoids; D012965:Sodium Chloride; D013973:Thyrotropin-Releasing Hormone; D013974:Thyroxine