Counteraction of L- tetrahydropalmatine Against Bromocriptine- induced Hypoprolactin in Lactational Rats / 中药新药与临床药理

ABSTRACT

Objective To study the counteraction of l- tetrahydropalmatine (l- THP) against bromocriptine (Bro)- induced hypoprolactin in lactational rats and to prove that l- THP is an antagonist of dopamine D2 receptors. Methods The lactational rat model with hypoprolactin was established by subcutaneous injection of Bro (0.5 mg/kg).The counteraction of l- THP (6 and 18 mg/kg, ip)was evaluated by observing serum prolactin (PRL) level, weight growing in newly born rats, and histology changes of mammary gland. Results Bro (0.5 mg/kg, sc) reduced the PRL level and induced the dysplasia of mammary gland in lactational rats. Bro also caused the retardation of the weight growing in newly- born rats. l- tetrahydropalmatine 6 and 18 mg/kg ip remarkably increased the prolactin level and promoted the development of mammary gland in lactational rats models and promoted the weight growing in newly- born rats. Conclusion l- tetrahydropalmatine(l- THP) has an antagonism against dopamine D2 receptors.