Effect of Epilepsy and Sleep Deprivation on GABA B1 Receptor Gene Expression in Cerebellum and Behavioural Changes in Rats

Abstract

Epilepsy is one of the most common neurobehavioral disorders of the brain that can be the result of increased excitability of neurons in several brain regions, affecting at least 50 million people worldwide. It is an idiopathic disease and most of the causes of epilepsy are still unknown. Sleep is naturally recurring state characterized by reduced or absent consciousness, relatively suspended sensory activity, and inactivity of nearly all voluntary muscles. Sleep deprivation adversely affects the brain and cognitive function. Evidences show that epilepsy can disrupt sleep but its exact cause is still unknown. Cerebellum is a region of the brain that plays an important role in coordination of skilled activity with precision. Because of its ‘‘fine-tuning’’ function, damage to the cerebellum produces disorders in fine movement, equilibrium, posture and motor learning. GABAB receptors are involved in epilepsy, anxiety and depression, nociception, memory, addiction, and potentially sleep. Neuronal cells continuously produce free radicals and reactive oxygen species (ROS) as part of their metabolic processes and also during the establishment of convulsive process. The generation of free radicals in rat brain is increased following pilocarpine-induced seizures and status epilepticus (SE) which can be determined by Superoxide Dismutase (SOD) Assay. We investigated the alterations in behaviour of sleep deprived epileptic rats as well as alteration in the level of oxidative stress. Epilepsy was induced in Adult male Wistar rat by pilocarpine, which is known to be one of the best models for temporal lobe epilepsy. Rats were partially sleep deprived by modified disc over water method. The rats were kept awake for 10 hours daily during their sleep cycle by modified disc over water method. Body weight measurements were carried out during the experimental days. A decrease in body weight of Control + Sleep Deprived (C+SD) and Epileptic + Sleep Deprived (E+SD) was observed compare to Control (C) and Epileptic (E) group. SOD Assay was carried out in C and experimental rats. Because sleep deprivation indeed appears to induce a state of negative energy balance reflected by weight loss. SOD Activity was found to be significant (p<0001) higher in Liver, Kidney and Cerebral cortex of C+SD, E, E+SD as compare to C rats, while there is no significant difference in cerebellum of C+SD, E, E+SD as compare to C rats. This is because, Abstract TLE can be characterized by a permanent change in neurotransmitter systems and in development of the oxidative stress that is more facilitated in the brain rather than in other organs because it including a high consumption of oxygen, the presence of large quantities of oxidizable lipids and pro-oxidative metals, and its comparatively lower antioxidant capacity. Results show alteration in the level oxidative stress at the lipid or at the protein level in sleep-deprived animals, in the brain or in peripheral tissues. GABA is one of the most important inhibitory neurotransmitter of brain. GABA plays a key role in oxidative stress changes, behaviour changes, sleep and epilepsy through GABAB1 receptor. Both GABAA and GABAB receptor has been reported to decrease during epilepsy. Our next objective was to evaluate change in GABAB1 receptor gene expression in sleep deprived epileptic rats. A good quality total RNA was isolated which used for preparation of cDNA. GABAB1 specific primer was designed and used to check its expression. But we could not get the amplified product of the GABAB1 Receptor gene. Inclined Beam Walk Test is a good indicator of impairment in motor function and coordination of limb movement in sleep deprived and epileptic rats. A significant (p<0.01)decrease in the retention time on the inclined beam was observed in C+SD, E and E+SD compared to C suggesting impairment in their ability to integrate sensory input with appropriate motor commands to balance their posture on inclined beam, while sleep deprivation in control rats can make their situation worse. The Wire Grip Test (WGT) evaluates the gripping capacity of rats on wire. The grip function was considerably poor in C+SD, E and E+SD as compare to C rats, while there was no significant change in level of time and retention on wire between C+SD and E rats. WGT revealed a significant (p<0.001) decrease in the retention time on wire by C+SD, E and E+SD compared to C. This is because of damage in brain or peripheral region of body in epileptic condition or due to the excessive formation of ROS in brain can lead to impairment in motor function and sleep deprivation also cause impairment in motor or cognitive function and make their more worse.