Effect of injection of thyrotropin-releasing hormone into nucleus accumbens on pain discharges in nucleus parafascicularis of the thalamus in rats

Abstract

Glass microelectrode recording method was used to investigate the effect of injection of thyrotropin-releasing hormone (TRH) into nucleus accumbens, nucleus amygdalae or nucleus caudatus on unit discharges from pain-excitation neurons (PEN) in nucleus parafascicularis of the thalamus in rats. The results showed that: l) Injection of TRH into the nucleus accumbens resulted in a significant inhibition of pain discharges from PEN in nucleus parafascicularis, while injection of TRH into nucleus amygdalae, nucleus caudatus exerted no significant effect. 2) Pretreatment with atropine abolished the above-mentioned effect of TRH. 3) Pretreatment with haloperidol also abolished the above-mentioned inhibitory effect of TRH. 4) Pretreatment with naloxone, propranolol or phentolamine did not affect the inhibitory effect of TRH. These results suggested that nucleus accumbens might be a special area in response to TRH and the effect of TRH seems to be involved in both cholinergic M-receptor and dopaminergic receptor.

Keywords

nucleus accumbens / nucleus parafascicularis / thyrotropin-releasing hormone / atropine / haloperidol

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