Cocaine transiently impairs maternal behavior in the rat.

This paradigm distinguished between two hypotheses not previously directly addressed. Do repeated exposures to cocaine at critical times during pregnancy, when the neural mechanisms that support maternal behavior are being read, alter some fundamental neural underpinning of maternal behavior in rats? Alternatively, does cocaine alter maternal behavior only when circulating? During the 4 hr after cocaine injection (20 or 40 mg/kg), there were significant deficits in maternal behavior. In contrast, 16 hr after cocaine injection, drug-injected females, in which plasma cocaine had fallen to nondetectable levels, showed the normal maternal behavior of saline-injected controls. This pattern of impaired maternal behavior after cocaine injection, followed by normal behavior as blood levels returned to zero, was replicated over 8 days. It was concluded that cocaine impairs maternal behavior only when circulating and does not have a residual effect in the transiently drug-free, chronically drug-treated dam.