G-Protein-Coupled Receptor 30 Mediates Rapid Neuroprotective Effects of Estrogen via Depression of NR2B-Containing NMDA Receptors

Abstract

17-␤-Estradiol (E2)is a steroid hormone involved in neuroprotection against excitotoxicity and other forms of brain injury. Through genomic and nongenomic mechanisms, E2 modulates neuronal excitability and signal transmission by regulating NMDA and non-NMDA receptors. However, the mechanisms and identity of the receptors involved remain unclear, even though studies have suggested that estrogen G-protein-coupled receptor 30 (GPR30) is linked to protection against ischemic injury. In the culture cortical neurons, treatment with E2 and the GPR30 agonist G1 for 45 min attenuated the excitotoxicity induced by NMDA exposure. The acute neuroprotection mediated by GPR30 is dependent on G-protein-coupled signals and ERK1/2 activation, but independent on transcription or translation. Knockdown of GPR30 using short hairpin RNAs (shRNAs) significantly reduced the E2-induced rapid neuroprotection. Patch-clamp recordings revealed that GPR30 activation depressed exogenous NMDA-elicited currents. Short-term GPR30 activation did not affect the expression of either NR2A-or NR2B-containing NMDARs; however, it depressed NR2B subunit phosphorylation at Ser-1303 by inhibiting the dephosphorylation of death-associated protein kinase 1 (DAPK1). DAPK1 knockdown using shRNAs significantly blocked NR2B subunit phosphorylation at Ser-1303 and abolished the GPR30-mediated depression of exogenous NMDA-elicited currents. Lateral ventricle injection of the GPR30 agonist G1 (0.2 g) provided significant neuroprotection in the ovariectomized female mice subjected to middle cerebral artery occlusion. These findings provide direct evidence that fast neuroprotection by estradiol is partially mediated by GPR30 and the subsequent downregulation of NR2B-containing NMDARs. The modulation of DAPK1 activity by GPR30 may be an important mediator of estradiol-dependent neuroprotection.

Neuroprotection of Sesamin against Cerebral Ischemia In-Vivo and N-Methyl-D-Aspartate-Induced Apoptosis In-Vitro

“…In the present study, a mouse model of transient focal cerebral ischemia induced by a 2 h MCAO and 24 h reperfusion was used to evaluate the neuroprotective effects of sesamin. Previous studies have reported that MCAO damages the structure of the neurons and other cells that support the neurons [20,34] and decreases neurological function [20]. Our results suggested that sesamin reduces the infract volume in the brain of MCAO mice and improves the neurological deficit score.…”

“…The Animal Care and Use Committee of the Fourth Military Medical University approved all of the animal protocols used. Prefrontal cortex neurons were cultured as described previously [20]. Briefly, the prefrontal cortex was dissected, minced, and trypsinized at 37ºC for 10 min using 0.25% trypsin (Invitrogen, Carlsbad, CA).…”

Non-receptor-tyrosine Kinases Integrate Fast Glucocorticoid Signaling in Hippocampal Neurons

“…Although some earlier studies observed immunoreactivity corresponding to the classical, nuclear GR in the plasma membrane (12,15,40,42), more recent ones have proposed that the fast actions of CORT in hippocampal neurons are mediated by translocated nuclear MR (7,43). It is pertinent to note that recent work has implicated an orphan GPCR in fast signaling by two other steroid hormones, estradiol and aldosterone (44,45); the latter is enzymatically (18-hydroxylase and 18-hydroxysteroid dehydrogenase) derived from CORT.…”

A New Chiral Pyrrolyl α-Nitronyl Nitroxide Radical Attenuates β-Amyloid Deposition and Rescues Memory Deficits in a Mouse Model of Alzheimer Disease

“…Cultured prefrontal cortex neurons were prepared as described previously [26]. Briefly, the prefrontal cortex was dissected, minced, and trypsinized for 15 min using 0.125 % trypsin (Invitrogen, Carlsbad, CA).…”

“…Western blot analysis was performed as described previously [26]. Equal amounts of protein (50 μg/lane) from the cultures were separated and electrotransferred onto polyvinylidene fluoride membranes (Invitrogen), which were incubated with rabbit polyclonal anti-tau (1:1000; Santa Cruz Biotechnology, Santa Cruz, CA), rabbit polyclonal anti-p-Tau (Ser235) (1:1000; Santa Cruz Biotechnology), rabbit polyclonal antip-Tau (Thr205) (1:1000; Santa Cruz Biotechnology), and mouse monoclonal anti-β-actin (1:4000; Sigma) as an internal control.…”