Cocaine and caffeine alter excitatory synaptic properties and intracellular [Ca2+] in somatosensory thalamic neurons.

CELESTE RIVERO-ECHETO; JAVIER A. MUÑIZ; VERONICA BISAGNO; CARLOTA GONZÁLEZ INCHAUSPE; BETINA GONZÁLEZ; FRANCISCO J. URBANO; PAULA PERISSINOTTI; EDGAR GARCÍA-RILL

Congreso; 2nd FALAN Congress (Federación de Sociedades de Neurociencias de Latinoamérica y el Caribe); 2016

FALAN (Federación de Sociedades de Neurociencias de Latinoamérica y el Caribe)

We studied the effects of an acute binge administration of caffeine, cocaine or both combined on synaptic properties of Ventrobasal neurons (VB). Male C57/BL6 mice were treated with cocaine (10 mg/kg; 3 inj. 1 hr apart, i.p.), caffeine (5mg/kg; 3 inj. 1 hr apart, i.p.), their combination (CC) (10 mg/kg Coc + 5 mg/kg Caf 3 inj. 1 hr apart, i.p.), vehicle (Veh: Saline solution) and A1 adenosine receptor antagonist DPCPX (5mg/kg). We recorded VB neurons 24 hs after last binge injection using whole cell patch-clamp and investigated the effect of these treatments on glutamatergic evoked activity and action potential alteration onto VB neurons. We also evaluated the total VB calcium concentration in VB neurons with fura-2 ratiometric calcium imaging registration before and after bath application of caffeine (20 mM). We observed that paired-pulse evoked glutamatergic currents (EPSC) showed greater facilitation at 40Hz compared to 1Hz frequency stimulation in CC group. Other groups didn?t show significant differences (cocaine, n=6; CC, n= 6; caffeine, n=6 and Veh, n=8; ANOVA, p<0.05). We then used fura-2 (50µM) ratiometric fluorescence recordings of VB neurons during a single low-threshold T-type calcium channel mediated spike generated in current-clamp mode after a rebound of a -200 pA hyperpolarizing current pulse. There was an increment in the area of Fura-2 fluorescence signals in both Veh and Caffeine treated groups after bath caffeine application (Control n=13, caffeine n=6; Paired t-test p<0.05). Further characterization of the role of T-type and IH calcium currents on the caffeine effects on intracellular [Ca2+] will be studied. Our data demonstrate that Cocaine+Caffeine alters excitatory synaptic transmission onto VB. Prestamo BID PICT-2012-0924, PICT-2012-1769 and PICT-2015-2594, Argentina/ NIH award P20 GM103425 to UAMS, USA.