The family of voltage-gated potassium Kv2 channels consists of the Kv2.1 and Kv2.2 subtypes. Kv2.1 is constitutively highly phosphorylated in neurons and its function relies on its phosphorylation state. Whether the function of Kv2.2 is also dependent on its phosphorylation state remains unknown. Here, we investigated whether Kv2.2 channels can be phosphorylated by protein kinase C (PKC) and examined the effects of PKC-induced phosphorylation on their activity and function. Activation of PKC inhibited Kv2.2 currents and altered their steady-state activation in HEK293 cells. Point mutations and specific antibodies against phosphorylated S481 or S488 demonstrated the importance of these residues for the PKC-dependent modulation of Kv2.2. In layer II pyramidal neurons in cortical slices, activation of PKC similarly regulated native Kv2.2 channels and simultaneously reduced the frequency of action potentials. In conclusion, this study provides the first evidence to our knowledge that PKC-induced phosphorylation of the Kv2.2 channel controls the excitability of cortical pyramidal neurons.
Action Potentials ; HEK293 Cells ; Humans ; Protein Kinase C/metabolism* ; Pyramidal Cells/enzymology* ; Shab Potassium Channels/genetics*

OBJECTIVETo study the effects and possible mechanisms of effective composite of Naodesheng (NDS) on permanent cerebral ischemia-induced injury in rats.

METHODSMale Sprague-Dawley rats: with middle cerebral artery occlusion (MCAO) were established with the modified suture method, and they were randomly divided into the following groups: the sham-operated group, the model group, the Nimodipine group (0.012 g/kg), the NDS group (1.075 g/kg), the total extracts group (0.23 g/kg), the high-dose NEC group (0.07 g/kg), the middle-dose NEC group (0.02 g/kg), and the low-dose NEC group (0.007 g/kg). The aforesaid medicines were administered at the 2nd, 4th, and 24th h after focal cerebral ischemia, and the infarction size and water content in the brain were evaluated at the 26th h after MCAO. Then, after oral administration once daily for 7 successive days, the changes in the degree of neurological deficit, oxidative stress, and apoptosis were measured on the 7th day.

RESULTSNEC could significantly reduce the infarction size after focal cerebral ischemia, and slightly relieve water content in the brain, significantly alleviate neurological function impairment, increase the levels of superoxide dismutase (SOD) and adenosine triphosphate enzyme (ATPase) activity, and decrease the content of malondialdehyde (MDA). NEC could also extenuate Bax and caspase-3 expression in the hippocampus tissue of the ischemic region. As compared with the three NEC treated groups, the high-dose NEC showed better efficacy.

CONCLUSIONSNEC could significantly reduce brain injury induced by ischemia;: its mechanism was closely associated with hindering oxidative stress and apoptosis. The effective composite-guided methodology is a feasible tool to improve the neuro-protective properties of the Chinese medicine guided prescription NDS against focal cerebral ischemia in rats.

Adenosine Triphosphatases ; metabolism ; Animals ; Blotting, Western ; Brain Ischemia ; prevention & control ; Caspase 3 ; metabolism ; Drugs, Chinese Herbal ; pharmacology ; Hippocampus ; enzymology ; metabolism ; pathology ; Male ; Malondialdehyde ; metabolism ; Neuroprotective Agents ; pharmacology ; Pyramidal Cells ; drug effects ; Rats ; Rats, Sprague-Dawley ; Superoxide Dismutase ; metabolism ; bcl-2-Associated X Protein ; metabolism