GluN2D subunit-containing NMDA receptors regulate reticular thalamic neuron function and seizure susceptibility.

Thalamic regulation of cortical function is important for several behavioral aspects including attention and sensorimotor control. This region has also been studied for its involvement in seizure activity. Among the NMDA receptor subunits GluN2C and GluN2D are particularly enriched in several thalamic nuclei including nucleus reticularis of the thalamus (nRT). We have previously found that GluN2C deletion does not have a strong influence on the basal excitability and burst firing characteristics of reticular thalamus neurons. Here we find that GluN2D ablation leads to reduced depolarization-induced spike frequency and reduced hyperpolarization-induced rebound burst firing in nRT neurons. Furthermore, reduced inhibitory neurotransmission was observed in the ventrobasal thalamus (VB). A model with preferential downregulation of GluN2D from parvalbumin (PV)-positive neurons was generated. Conditional deletion of GluN2D from PV neurons led to a decrease in excitability and burst firing. In addition, reduced excitability and burst firing was observed in the VB neurons together with reduced inhibitory neurotransmission. Finally, young mice with GluN2D downregulation in PV neurons showed significant resistance to pentylenetetrazol-induced seizure and differences in sensitivity to isoflurane anesthesia but were normal in other behaviors. Conditional deletion of GluN2D from PV neurons also affected expression of other GluN2 subunits and GABA receptor in the nRT. Together, these results identify a unique role of GluN2D-containing receptors in the regulation of thalamic circuitry and seizure susceptibility which is relevant to mutations in GRIN2D gene found to be associated with pediatric epilepsy.

Role of Nrf2 dysfunction in the pathogenesis of diabetic nephropathy: Therapeutic prospect of epigallocatechin-3-gallate.

Diabetic nephropathy (DN), a progressive kidney disease afflicts more than 20 and up to 40% of the diabetic population and it is characterized by persistent microalbuminuria declined glomerular filtration rate. The interesting feature associated with DN is that, even though the progression of the disease correlates with oxidative stress, Nrf2, the master regulator of antioxidant defense system involved in counteracting oxidative stress is also upregulated in the diabetic kidneys of both human as well as experimental animals in early stages of DN. Despite the increased expression, the ability of this protein to get translocated into the nucleus is diminished signifying the functional impairment of Nrf2, implying redox imbalance. Hence, it is understood that agents that boost the translocation of Nrf2 might be beneficial rather than those that quantitatively overexpress Nrf2 in treating DN. The deleterious effects of synthetic Nrf2 activators have instigated the researchers to search for phytochemicals that have ambient Nrf2 boosting ability with no side effects, one such phytochemical is Epigallocatechin-3-gallate (EGCG) and it has shown beneficial effects by preventing the progression of DN via influencing Nrf2/ARE pathway, however, the modus operandi is unclear, despite speculations. This study was designed to find out whether supplementation of Nrf2 booster like EGCG at the crucial time of Nrf2 dysfunction can mitigate the progression of DN. Based on the findings of the present study, it might be concluded that the beneficial effect of EGCG in mitigating DN is mediated mainly through its ability to activate the Nrf2/ARE signaling pathway at multiple stages i.e., by downregulating Keap1 and boosting the nuclear Nrf2 level by disrupting Nrf2-Keap1 interaction. These results emphasize that supplementation of EGCG might be more beneficial at an early stage of DN, where dysfunctional Nrf2 accumulation occurs, which should be further validated.

Amelioration of apoptotic events in the skeletal muscle of intra-nigrally rotenone-infused Parkinsonian rats by Morinda citrifolia--up-regulation of Bcl-2 and blockage of cytochrome c release.

Parkinson's disease is a progressive neurodegenerative movement disorder with the cardinal symptoms of bradykinesia, resting tremor, rigidity, and postural instability, which lead to abnormal movements and lack of activity, which in turn cause muscular damage. Even though studies have been carried out to elucidate the causative factors that lead to muscular damage in Parkinson's disease, apoptotic events that occur in the skeletal muscle and a therapeutical approach to culminate the muscular damage have not been extensively studied. Thus, this study evaluates the impact of rotenone-induced SNPc lesions on skeletal muscle apoptosis and the efficacy of an ethyl acetate extract of Morinda citrifolia in safeguarding the myocytes. Biochemical assays along with apoptotic markers studied by immunoblot and reverse transcription-polymerase chain reaction in the current study revealed that the supplementation of Morinda citrifolia significantly reverted alterations in both biochemical and histological parameters in rotenone-infused PD rats. Treatment with Morinda citrifolia also reduced the expression of pro-apoptotic proteins Bax, caspase-3 and caspase-9 and blocked the release of cytochrome c from mitochondria induced by rotenone. In addition, it augmented the expression of Bcl2 both transcriptionally and translationally. Thus, this preliminary study paves a way to show that the antioxidant and anti-apoptotic activities of Morinda citrifolia can be exploited to alleviate skeletal muscle damage induced by Parkinsonism.