ISSN : 1226-9654
본 연구의 목적은 benzodiazepine 수용기에 대해 효능제로 작용하는 diazepam(DZP)과 역전 효능제로 작용하는 β-CCM의 장기투여가 조건 공포반응의 지표인 행동동결에 미치는 효과를 검토하고자 하는 것이다. 실험 1에서 DZP의 훈련전 단기투여는 조건 행동동결을 감소시켰으나, 훈련전 장기투여는, 조건 행동동결을 감소시키지 못하였으므로, 내성효과를 나타내었다. 실험 2에서 β-CCM의 투여는 조건 행동동결을 증가시켰고, 단기투여와 장기투여의 효과차이는 없었다. 효능제와 역전 효능제의 효과가 반대라는 결과는 흰쥐의 종특유의 방어반응인 조건행동동결이 benzodiazepine 수용기를 중개로 하여 학습되는 반응임을 입증해 주는 것이다. 아울러 효능제의 경우에는 장기투여에 의해 내성효과를 일으킴을 시사해 준다.
This study investigated the effects of chronic injection of benzodiazepine agonist, diazepam(2mg/kg) and inverse agonist, β-CCM(1mg/kg) on the conditioned freezing in Sparague-Dawley male rats, using 2-trial conditioned fear test. Each animal in chronic treatment groups was injected twice a day for 5 days. Each animal in acute treatment groups was injected only once before training. On the first training day, each rat was placed in the observation chamber, and 3 min later it recieved three shock (0.75s, 1mA) at a 20-s intershock interval. During the second testing day, the animal's behavior was observed according to a time-sampling procedure in the same preshocked chamber. Results showed that the conditioned freezing was significantly reduced in animals treated with single injection of diazepam, administered before the 1st training trial, but not in those treated with repeated injections of diazepam(exp 1). In constrast, both single and repeated injections of β-CCM caused an increasing in the conditioned freezing response(exp 2). The finding that the acute treatment of diazepam given before training attenuate the conditioned freezing was consistent with our previous study. It was also founded that the repeated administrations of diazepam induced tolerance effect and the effects of agonist and inverse agonist ligands of benzodiazepine receptor on conditioned freezing were contrary to each other. It is suggested that benzodiazepine receptors are involved in the control of the rat's species-specific defensive response.