Impact of prenatal and acute methamphetamine exposure on behaviour of adult male rats.

Psychostimulants have been shown to alter behaviour in both rats and humans. The aim of the present study was: (1) to assess the effect of prenatal and acute methamphetamine (MA) administration on behaviour in adult male rats and (2) to find out if the prenatal exposure to MA increases sensitivity to acute MA application in adulthood. Behaviour of adult male rats prenatally exposed to MA (5 mg/kg) or no drug was tested in Open field (OF) and Elevated plus maze (EPM). Half of the animals were injected with MA (1 mg/kg) subcutaneously 30 minutes prior to testing. Locomotion, exploration, comforting behaviour and anxiety were evaluated in the OF, while anxiety and exploratory behaviour were assessed in the EPM. Our results showed that prenatal MA did not have an effect on baseline behaviour in either of the tests. By contrast, acute MA increased overall psychomotor activity by increasing locomotion and exploratory behaviour and decreasing comforting behaviour. Moreover, adult rats prenatally exposed to MA were more sensitive to the effects of acute MA on exploration. In addition, acute MA application decreased anxiety in the OF as well as in the EPM. Our present study, thus, demonstrates that acute MA increases overall psychomotor activity and decreases anxiety to novel environment. To further support our hypothesis that prenatal MA exposure increases sensitivity to drugs in adulthood, studies investigating the levels of dopamine in the rat brain after prenatal MA exposure are planned.