Paper Information

Title: 

ENHANCEMENT OF FAST INACTIVATING K+ CHANNEL FUNCTION INDUCES HYPO-EXCITABILITY IN PURKINJE NEURONS OF YOUNG OFFSPRING MATERNALLY EXPOSED TO WIN 55212-2

Type: POSTER
Author(s): SHAABANI MOHAMMAD,KAFASHIAN M.R.,SHEYBANI VAHID,JANAHMADI MAHYAR
 
 
 
Name of Seminar: IRANIAN CONGRESS OF PHYSIOLOGY AND PHARMACOLOGY
Type of Seminar:  CONGRESS
Sponsor:  PHYSIOLOGY AND PHARMACOLOGY SOCIETY, MASHHAD UNIVERSITY OF MEDICAL SCIENCE
Date:  2009Volume 19
 
 
Abstract: 

Activation of cannabinoid CB1 receptors modulates many types of ion channels, suggesting that they may constitute potential therapeutic targets in neuronal diseases. To address the electrophysiological consequences of maternal exposure to cannabinoids, Wistar rats received win 55212-2 (0.5 mg/kg/day, sc) from day 5 to 20 of pregnancy. Then, whole cell patch clamp recording was performed in 30 to 40 day old offspring of either control or win-treated mothers. Parasagital slices from the Cerebellar Vermis were prepared and recordings were done from Purkinje neurons. Prenatal Win exposure significantly increased the firing precision, as evidenced by a decrease in the coefficient of variation (0.06±0.005 compared to 0.11±0.02 in control, p<0.05). Instantaneous firing frequency was significantly decreased (from 139.2±13 Hz in control to 89.2±4 in win treated, p<0.001), as Purkinje cells became hypo-excitable. The first rebound spike latency was also significantly longer in win-treated group with increasing prehyperpolarization level. The robust rebound action potentials observed after a hyperpolarizing current pulses in control condition were significantly suppressed in win-treated rats (e.g. 8.8± 1.4 in control to 3.6±1 in win-exposed following -0.5 nA hyperpolarizing current pulse, p<0.001). The peak amplitude of action potential was also significantly increased following win treatment (from 44.3±2.5 in control to 52.8±1.1 in Win treated, p<0.05). These findings suggest that activation of cannabinoid receptors profoundly alters the Purkinje neuron excitability possibly through enhancement of the fast inactivating K+ channel currents. Therefore, this may provide an insight for therapeutic intervention in a condition under which neuronal hyper-excitability becomes abnormal.

 
Keyword(s): CANNABINOID, PRENATAL EXPOSURE, CEREBELLAR PURKINJE NEURONS, WHOLE CELL PATCH CLAMP
 
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