Effect of injection of TRH into cerebral ventricles on the analgesic effect of acupuncture and morphine in rats

Abstract

Value of pain threshold of rats as index was determined by radiant heat-induced tail-flick to observe the effects of injection of TRH (10 μ/20 μ1) into cerebral ventricles (i.c.v.) on the analgesic effect induced by electro-acupuncture (1, 2 or 3 V) of bilateral “Zu San Li” and “San Yin Jiao”, and s.c. injection of morphine (2, 4, 6 mg/kg). The results of our study indicated that injection of TRH i.c.v. does not influence the radiant heat-induced tail-flick response of rats under normal condition, but antagonizes the analgesic effect caused by electro-acupuncture 2 and 3 V in strength and by s.c. infection of morphine (2, 4 mg/kg).

Keywords

thyrotropin-releasing-hormone (TRH) / electro-acupuncture / morphine / radiant heat-induced tail-flick

References

[1] MorleyJE, et al. . Extrahypothalamic thyrotropin releasing hormone (TRH) -its distribution and its functions. Life Sci, 1979, 251539-50

[2] JacksonIMD. Thyrotropin-releasing hormone. New Eng J Med, 1982, 306(3): 145-55

[3] HoritaA, et al. . Influence of thyrotropin releasing hormone (TRH) on drug-induced narcosis and hypothermia in rabbits. Psychopharmacology, 1976, 4957-62

[4] BreeseGR, et al. , et al. . LombardiniJB, KennyAD, et al. , et al. . Effects of thyrotropin releasing hormone on central nervous system function. The Role of Peptides and Amino Acids as Neurotransmitters, 1981, New York, Liss Inc.: 99-99

[5] 1978;30(2):204–8.

[6] 1980: 448–53.

[7] MartinBR, et al. . Interactions of thyrotropin releasing hormone and morphine sulfate in rodents. Life Sci, 1977, 20715-22

[8] SmithJR. The effects of thyrotropinreleasing hormone on cyclic AMP accumulation in rabbit cerebral cortical tissue in presence and absence of CNS depressants. Life Sci, 1981, 282065-9

[9] cAMP cGMP1981: 13:31–3.

[10] 1979:129–30.

[11] 1979: 128.