Involvement of dopaminergic system in the nucleus accumbens in the discriminative stimulus effects of phencyclidine

Evaluation of cognitive behaviors in young offspring of C57BL/6J mice after gestational nicotine exposure during different time-windows

Gestational nicotine exposure is associated with cognitive abnormalities in young offspring. However, practical strategies for prevention or treatment of impaired cognitive behaviors of offspring are not available due to the lack of systematic investigation of underlying mechanism. Therefore, this study aimed at examining the effects of gestational and/or perinatal nicotine exposure (GPNE) on cognitive behaviors in offspring of C57BL/6J mice to provide systematic behavioral data. Pregnant mice were exposed to nicotine via sweetened drinking water during six time-windows, including gestational day 0 to day 13 (G0-G13), G14-postnatal day 0 (P0), G0-P0, G14-P7, G0-P7, and P0-P7. During P42-P56 days, both male and female offspring were given a battery of behavioral tests. Depending on the time of exposure, GPNE impaired working memory, object-based attention, and prepulse inhibition in male and female offspring to different extents. Nicotine exposure during G14-P0 also decreased norepinephrine turnover in the prefrontal cortex on P28 and P56. Overall results indicate that nicotine exposure during any time-windows of development impairs cognitive behaviors in offspring, and suggest that certain time-windows, e.g., G14-P0, should be selected for further studies on the underlying neurochemical or molecular mechanisms.

Evaluation of object-based attention in mice

The deficits of attention result in significant impairment in daily life, and pharmacological intervention to improve attention is the most effective treatment in clinics. However, methods which are suitable for the large scale preclinical screening of attention-improving compounds or drugs are few in the field. In this study, we have developed object-based attention task as a simple and wherever-practical method that suitable for quick drug screening in mice. Treatment with p-chlorophenylalanine (pCPA) (200mg/kg/day, i.p.) for three consecutive days reduced the prefrontal cortical content of serotonin and dopamine, and increased turn-over of dopamine while decreasing turn-over of norepinephrine in the prefrontal cortex on day 7. Auditory attention and working memory, but not long-term object memory after a long (10 min) object (two objects)-exposure period, were impaired on day 7 after the same treatment paradigm with pCPA. Novel object recognition ability immediately (<10s) after a short (3 min) object (on two objects)-exposure period was not impaired after pCPA treatment. However, novel object recognition ability immediately (<10s) after a short (3 min), but not long (6 min), object (five objects)-exposure period was impaired after pCPA treatment. For the verification, the current task, the object-based attention task, was confirmed in an attention deficit model induced by acute phencyclidine (1mg/kg, i.p.) treatment in mice. It was implied that the object-based attention task would assist the behavioral screening process of pharmacological studies on attention-improving drugs.