Synergetic Inhibition of Bromocrptine and Baclofen on the Naloxone-induced Withdrawal Syndromes

Mice were administrated by the consecutive morphine, subcutaneous injection (25, 50, 75, 100, 125, 150 mg/kg）to establish the withdrawal model. The naloxone (6 mg/kg)-induced responses, namely jumping behavior can be observed as withdrawal behavior. Bromocriptine and baclofen were used in the protocol and their synergetic inhibition was also studied. The results suggested that the low dose of bromocriptine (10 mg/kg) can not inhibit the withdrawal syndromes , whereas the mid (20 mg/kg) and high (30 mg/kg) doses can do. The low (0.5 mg/kg) and mid (1.0 mg/kg) doses of baclofen can not decrease the withdrawal syndromes, whereas the high dose can effectively inhibit the nalxone-induced response in the mice. However the co-administration of bromocriptine (10 mg/kg) and baclofen (1.0 mg/kg) can inhibit the withdrawal response. The results showed that the two receptors synergized and effectively inhibited the naloxone-induced withdrawal syndromes.