Fig. 2.

Synaptic Dopamine Release and Clearance in the NAc Are Increased by Long Summer-like Photoperiod in an Age-Dependent Manner: A) Representative current traces across tonic and phasic frequencies in the NAc core of periadolescent (P30) or B) young adult (P50) mice raised in Short, Equinox, or Long photoperiods. C) Evoked NAc core dopamine release across tonic and phasic frequencies in the periadolescent age group showed a main effect of frequency of stimulation (F(3, 68) = 5.981; p = 0.0011). D) In the young adult group, there was a significant main effect of frequency of stimulation (F (3, 64) = 3.172; p = 0.0301) and photoperiod (F (2, 64) = 13.32; p < 0.0001) on evoked NAc dopamine release. E) NAc dopamine release evoked from the single pulse condition showed a main effect of photoperiod (F (2, 31) = 5.374; p = 0.0099), age (F (1, 31) = 11.76; p = 0.0017), as well as an interaction effect (F (2, 31) = 4.453; p = 0.02). F) Tau, the time it takes for the dopamine signal to decay to 1/3 of its peak value, was used to assess dopamine clearance. There was a main effect of photoperiod (F(2,33) = 3.915; p = 0.0298), age (F(1,33) = 5.0; p = 0.0322) and an interaction effect (F(2,33) = 4.369; p = 0.0207). Data are represented as mean±SEM. * = Short vs Long, # = Long vs. Equinox. *p < 0.05, **p < 0.01, ****p < 0.0001. Males: Short, P30 (N = 4), Short, P50 (N = 3); Equinox, P30 (N = 3), Equinox, P50 (N = 3); Long, P30 (N = 3), Long P50 (N = 3). Females: Short, P30 (N = 3), Short, P50 (N = 3), Equinox, P30 (N = 3), Equinox, P50 (N = 4), Long, P30 (N = 4), Long, P50 (N = 3).