Differential effects of methylphenidate and cocaine binge on calcium dynamics of thalamic ventrobasal neurons in mice [Poster Number 207/Session I]

J. L. ROZAS; B. GOITIA; E. GARCIA-RILL; V. BISAGNO; F. J. URBANO

Huerta Grande, Cordoba

Congreso; XXVII Congreso SAN 2012; 2012

Sociedad Argentina de Investigacion en Neurociencias (SAN)

Cocaine (Coc), but not methylphenidate (MPH) binge administration has been described to enhance T-type calcium currents in the Ventrobasal nucleus (VB). However, the effects of these stimulants on intracellular [Ca2+] dynamics are unknown. Mice (male C57BL/6, P18-23) received one Coc or MPH binge (3x15 mg/kg i.p., 1h apart) or saline. VB neurons were patch-clamped using an egtafree intracellular solution with the high-affinity Ca2+ indicator bisfura-2 (60μM). Fluorescence was measured in somas and proximal dendrites during voltage steps from -70mV to -30mV or -10mV to maximally activate T- or P/Q-type Ca2+ currents. In dendrites, only MPH induced an increase in peak Ca2+ transients at -10mV and -30mV. Area under Ca2+ transients was bigger in dendrites at -30mV for the MPH group (n=12) compared to Coc (n=5; p=0.024). Dendrites/soma area ratios were bigger for the MPH group than for Coc or saline groups at -10mV and -30mV (-10mV: MPH 2.3±0.7, n=12; Coc 0.5±0.1, n=5; saline 0.7±0.1, n=4; -30mV: MPH 2±0.4; Coc 0.3±0.04; saline 0.7±0.3), indicating a larger entry of Ca2+ in proximal dendrites, where P/Q-type channels are known to mediate gamma band oscillations. These results suggest that MPH might be more effective than Coc in enhancing dendritic synaptic integration onto VB neurons. FONCYT-PICT 2007-1009, PICT 2008-2019 & PIDRI-PRH 2007 (Dr. Urbano), CONICET- PIP 2011-2013- 11420100100072 (Dr. Bisagno), NIH grants P20 GM103425-09, R01NS020246-25 (Dr. Garcia-Rill).