The 1-Adrenergic Receptor Antagonist, Doxazosin, Reduces Alcohol Drinking in Alcohol-Preferring (P) Rats

Background Evidence supports a role for the noradrenergic system in alcohol drinking in animals and humans. Our previous studies demonstrated the efficacy of prazosin, an 1-adrenergic antagonist, in decreasing alcohol drinking in rat models of alcohol dependence. Prazosin has also been shown to decrease alcohol drinking in treatment-seeking alcohol-dependent men. Clinically, the use of prazosin is limited by the requirement for multiple daily administrations, whereas doxazosin, a structurally similar 1-adrenergic antagonist, requires only once-daily dosing. In this study, we tested the hypothesis that doxazosin, like prazosin, would decrease alcohol drinking in rats selectively bred for alcohol preference (P line). Methods Adult male P rats were given 2h/d scheduled access to a 2-bottle choice (15% v/v alcohol vs. water) session 5d/wk (MF), with food and water available ad libitum 24h/d. Rats were injected with doxazosin (0 to 10mg/kg, IP) 40minutes prior to initiation of the alcohol access session in 3 trials (of 3, 5, and 5 consecutive days) each separated by 5 to 8weeks. The third trial included 1day without alcohol access (for locomotor testing), and 1day of a single hour of alcohol access (for plasma alcohol determination). Results Doxazosin significantly reduced alcohol intake in all 3 trials. The 5mg/kg dose consistently reduced alcohol intake, increased water drinking, did not affect locomotor activity, and resulted in lower plasma alcohol concentrations, suggesting that the doxazosin-induced reduction in alcohol drinking was not dependent on a motor impairment or an alteration in alcohol clearance. Conclusions Doxazosin decreases voluntary alcohol consumption by male alcohol-preferring (P) rats, supporting a role for the noradrenergic system in alcohol drinking in P rats and suggesting that doxazosin could potentially be an effective once-daily pharmacotherapeutic agent for the treatment of alcohol use disorders.