In vitro and in vivo displacement of [3H]-diazepam binding by purine derivatives in developing rat brain.

In vitro inhibiton of [3H]-diazepam binding to developing rat brain synaptosomal membranes has been studied. Adenosine, inosine, and hypoxanthine display approximately equal potencies as inhibitors of [3H]-diazepam binding to young rat brain membranes. In adult, inosine and hypoxanthine exhibit greater inhibitory potency. Data are also presented which show that the xanthine stimulants caffeine and theophylline competitively inhibit [3H]-diazepam binding with an equal potency throughout the development. In vivo study is also reported which shows that [3H]-diazepam binding to membranes from 5-day-old rats is displaced when female rats have been daily injected with caffeine or theophylline during gestation and lactation.