title: Effects of epinephrine and cortisol on the analgesic activity of metyrosine in rats.
abstract: Some endogenous hormones (epinephrine and cortisol) can change an individual's pain threshold. Propranolol is a non-selective β adrenergic receptor blocker which antagonises the anti-inflammatory effect of non-steroidal anti-inflammatory drugs via the β1 and β2 adrenergic receptors. The roles of epinephrine and cortisol were investigated in the analgesic activity of metyrosine in rats with reduced epinephrine levels induced by metyrosine. Pain threshold measurement was performed using an analgesimeter with different doses and the single or combined usage of metyrosine, prednisolone, metyrapone and propranolol in rats. Epinephrine and corticosterone levels were measured by high-performance liquid chromatography in metyrosineadministered rats. Metyrosine reduces the epinephrine levels without affecting the corticosterone levels, thereby creating an analgesic effect. It was determined that prednisolone did not have an analgesic effect in rats with normal epinephrine levels, but its analgesic activity increased with a parallel decrease in the epinephrine levels. Similarly, the combined use of prednisolone and metyrosine provided a stronger analgesic effect than that rendered by metyrosine alone. The strongest analgesic effect, however, was observed in the group of rats with the lowest epinephrine level in whom the metyrosine + prednisolone combination was administered. The findings of this study may be useful in severe pain cases in which the available analgesics are unable to relieve the individual's pain.
authors: Department of General Surgery, Regional Education and Research Hospital, 25240 Erzurum, Turkey.
authors: Yavuz
authors: Y
authors: Albayrak
authors: Mustafa Bahadir
authors: MB
authors: Saglam
authors: Kadir
authors: K
authors: Yildirim
authors: Saliha
authors: S
authors: Karatay
authors: Beyzagul
authors: B
authors: Polat
authors: Turan
authors: T
authors: Uslu
authors: Halis
authors: H
authors: Suleyman
authors: Fatih
authors: F
authors: Akcay
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000008:administration & dosage / Q000494:pharmacology; D000700:Analgesics / Q000008:administration & dosage / Q000627:therapeutic use*; D000818:Animals; D002351:Carrageenan / Q000008:administration & dosage / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid; D003345:Corticosterone / Q000097:blood; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D004359:Drug Therapy, Combination; D004837:Epinephrine / Q000097:blood / Q000502:physiology*; D006854:Hydrocortisone / Q000097:blood / Q000502:physiology*; D008297:Male; D008797:Metyrapone / Q000008:administration & dosage / Q000494:pharmacology; D010146:Pain / Q000097:blood / Q000139:chemically induced / Q000188:drug therapy*; D017288:Pain Threshold; D011239:Prednisolone / Q000008:administration & dosage / Q000627:therapeutic use*; D011433:Propranolol / Q000008:administration & dosage / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors; D019805:alpha-Methyltyrosine / Q000008:administration & dosage / Q000627:therapeutic use*
chemical_list: D000319:Adrenergic beta-Antagonists; D000700:Analgesics; D019805:alpha-Methyltyrosine; D002351:Carrageenan; D011239:Prednisolone; D011433:Propranolol; D003345:Corticosterone; D006854:Hydrocortisone; D004837:Epinephrine; D008797:Metyrapone