Šaltinis
Dept. of Psychology, Univ. of Illinois at Chicago, Chicago, IL 60607. [apsaugotas el. paštu].
Abstraktus
Adolescence may be a period of vulnerability to drug addiction. In žiurkės, elevated firing activity of ventralinė tegmental plotas (VTA) dopamino neuronai predicts enhanced addiction liability. Our aim was to determine if dopamino neuronai are more active in adolescents than in suaugusieji and to examine mechanisms underlying any age-related difference. VTA dopamino neuronai atleistas greičiau in adolescents than in suaugusieji as measured with in vivo extracellular recordings. Dopaminas neuron firing can be divided into nonbursting (single spikes) and bursting activity (clusters of high-frequency spikes). Nonbursting activity was higher in adolescents compared with suaugusieji. Frequency of burst events did not differ between ages, but bursts were longer in adolescents than in suaugusieji. Padidėjęs dopamino neuron firing in paauglys žiurkės was also observed in cell-attached recordings in ex vivo brain slices. Using whole cell recordings, we found that passive and active membrane properties were similar across ages. Hyperpolarization-activated cation currents and small-conductance calcium-activated potassium channel currents were also comparable across ages. We found no difference in dopamino D2-class autoreceptor function across ages, although the high baseline firing in adolescents resulted in autoreceptor activation being less effective at silencing neuronai. Finally, AMPA receptor-mediated spontaneous excitatory postsynaptic currents occurred at lower frequency in adolescents; GABA(A) receptor-mediated spontaneous inhibitory postsynaptic currents occurred at both lower frequency and smaller amplitude in adolescents. In conclusion, VTA dopamino neuronai ugnis greičiau in adolescence, potentially because GABA tone increases as žiurkės reach adulthood. This elevation of firing rate during adolescence is consistent with it representing a vulnerable period for developing drug addiction.
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