No abstract

Increased glutamate NMDA receptor (NMDAR) activity in the paraventricular nucleus (PVN) of the hypothalamus leads to augmented sympathetic outflow in hypertension. However, the molecular mechanisms underlying this effect remain unclear. α2δ-1, previously considered to be a voltage-activated calcium channel subunit, is a newly discovered powerful regulator of NMDARs. In the present study, we determined the role of α2δ-1 in regulating synaptic NMDAR activity of rostral ventrolateral medulla (RVLM)-projecting PVN neurons in spontaneously hypertensive rats (SHRs). We show that the protein levels of α2δ-1 and NMDARs in synaptosomes and the α2δ-1-NMDAR complexes in the hypothalamus were substantially higher in SHRs than in normotensive control rats. The basal amplitude of evoked NMDAR currents and NMDAR-mediated synaptic glutamate release in RVLM-projecting PVN neurons were significantly increased in SHRs. Strikingly, inhibiting α2δ-1 activity with gabapentin or disrupting the α2δ-1-NMDAR association with an α2δ-1 C-terminus peptide completely normalized the amplitude of evoked NMDAR currents and NMDAR-mediated synaptic glutamate release in RVLM-projecting PVN neurons in SHRs. In addition, microinjection of the α2δ-1 C-terminus peptide into the PVN substantially reduced arterial blood pressure and renal sympathetic nerve discharges in SHRs. Our findings indicate that α2δ-1-bound NMDARs in the PVN are required for the potentiated presynaptic and postsynaptic NMDAR activity of PVN presympathetic neurons and for the elevated sympathetic outflow in hypertension. α2δ-1-bound NMDARs may be an opportune target for treating neurogenic hypertension.

An infectious bronchitis virus (IBV), ck/CH/LZJ/111113, was isolated from a H120-vaccinated chicken which showed disease suspected of IBV infection. Neutralization testing showed that ck/CH/LZJ/111113 was distinct from either the Chinese predominant IBV LX4-type or Mass-type vaccine strains. Phylogenetic analysis confirmed that ck/CH/LZJ/111113 is of the 4/91 type; however, further extensive analyses of full-length genomes identified occurrence of recombination events. Therefore, ck/CH/LZJ/111113 originated from the recombination events between ck/CH/LDL/091022- and 4/91-like strains at three switch sites located upstream of the spike (S) glycoprotein gene, and the 3' ends of S1 and nuceocapsid (N) genes, respectively. The difference of serotypes and tissue tropisms in kidneys between ck/CH/LZJ/111113 and ck/CH/LDL/091022 may have been contributed by the uptake of the S1 gene by a ck/CH/LDL/091022-like virus from a 4/91-like strain. This recombination event took place at the 3' end of the N gene and the 3' untranslated region may account for differences in replication efficiency in tissues of chickens inoculated by the two viruses.

Both the sympathetic nervous system and the renin-angiotensin system are critically involved in hypertension development. Although angiotensin II (Ang II) stimulates hypothalamic paraventricular nucleus (PVN) neurons to increase sympathetic vasomotor tone, the molecular mechanism mediating this action remains unclear. The glutamate NMDAR in the PVN controls sympathetic outflow in hypertension. In this study, we determined the interaction between α2δ-1 (encoded by ), commonly known as a Ca channel subunit, and NMDARs in the hypothalamus and its role in Ang II-induced synaptic NMDAR activity in PVN presympathetic neurons. Coimmunoprecipitation assays showed that α2δ-1 interacted with the NMDAR in the hypothalamus of male rats and humans (both sexes). Ang II increased the prevalence of synaptic α2δ-1-NMDAR complexes in the hypothalamus. Also, Ang II increased presynaptic and postsynaptic NMDAR activity via AT1 receptors, and such effects were abolished either by treatment with pregabalin, an inhibitory α2δ-1 ligand, or by interrupting the α2δ-1-NMDAR interaction with an α2δ-1 C terminus-interfering peptide. In knock-out mice (both sexes), Ang II failed to affect the presynaptic and postsynaptic NMDAR activity of PVN neurons. In addition, the α2δ-1 C terminus-interfering peptide blocked the sympathoexcitatory response to microinjection of Ang II into the PVN. Our findings indicate that Ang II augments sympathetic vasomotor tone and excitatory glutamatergic input to PVN presympathetic neurons by stimulating α2δ-1-bound NMDARs at synapses. This information extends our understanding of the molecular basis for the interaction between the sympathetic nervous and renin-angiotensin systems and suggests new strategies for treating neurogenic hypertension. Although both the sympathetic nervous system and renin-angiotensin system are closely involved in hypertension development, the molecular mechanisms mediating this involvement remain unclear. We showed that α2δ-1, previously known as a calcium channel subunit, interacts with NMDARs in the hypothalamus of rodents and humans. Angiotensin II (Ang II) increases the synaptic expression level of α2δ-1-NMDAR complexes. Furthermore, inhibiting α2δ-1, interrupting the α2δ-1-NMDAR interaction, or deleting α2δ-1 abolishes the potentiating effects of Ang II on presynaptic and postsynaptic NMDAR activity in the hypothalamus. In addition, the sympathoexcitatory response to Ang II depends on α2δ-1-bound NMDARs. Thus, α2δ-1-NMDAR complexes in the hypothalamus serve as an important molecular substrate for the interaction between the sympathetic nervous system and the renin-angiotensin system. This evidence suggests that α2δ-1 may be a useful target for the treatment neurogenic hypertension.

Background and Purpose: Glutamate N-methyl-D-aspartate receptors (NMDARs) play a major role in the initiation of ischemic brain damage. However, NMDAR antagonists have no protective effects in stroke patients, possibly because they impair physiological functions of NMDARs. α2δ−1 (encoded by Cacna2d1) is strongly expressed in many brain regions. We determined the contribution of α2δ−1 to NMDAR hyperactivity and brain injury induced by ischemia and reperfusion. Methods: Mice were subjected to 90 min of middle cerebral artery occlusion (MCAO) followed by 24 h of reperfusion. Neurological deficits, brain infarct volumes, and calpain/caspase-3 activity in brain tissues were measured. NMDAR activity of hippocampal CA1 neurons was measured in an in vitro ischemic model. Results: MCAO increased α2δ−1 protein glycosylation in the cerebral cortex, hippocampus, and striatum. Coimmunoprecipitation showed that ischemia rapidly enhanced the α2δ−1–NMDAR physical interaction in the mouse brain tissue. Inhibiting α2δ−1 with gabapentin, uncoupling the α2δ−1–NMDAR interaction with an α2δ−1 C-terminus–interfering peptide, or genetically ablating Cacna2d1 had no effect on basal NMDAR currents but strikingly abolished oxygen-glucose deprivation-induced NMDAR hyperactivity in hippocampal CA1 neurons. Systemic treatment with gabapentin or α2δ−1 C-terminus–interfering peptide or Cacna2d1 genetic knockout reduced MCAO-induced infarct volumes, neurological deficit scores, and calpain/caspase-3 activation in brain tissues. Conclusions: α2δ−1 is essential for brain ischemia-induced neuronal NMDAR hyperactivity, and α2δ−1–bound NMDARs mediate brain damage caused by cerebral ischemia. Targeting α2δ−1–bound NMDARs, without impairing physiological α2δ−1–free NMDARs, may be a promising strategy for treating ischemic stroke.

Vesicular glutamate transporter-2 (VGluT2) mediates the uptake of glutamate into synaptic vesicles in neurons. Spinal cord dorsal horn interneurons are highly heterogeneous and molecularly diverse. The functional significance of VGluT2-expressing dorsal horn neurons in physiological and pathological pain conditions has not been explicitly demonstrated. Designer receptors exclusively activated by designer drugs (DREADDs) are a powerful chemogenetic tool to reversibly control neuronal excitability and behavior. Here, we used transgenic mice with Cre recombinase expression driven by the VGluT2 promoter, combined with the chemogenetic approach, to determine the contribution of VGluT2-expressing dorsal horn neurons to nociceptive regulation. Adeno-associated viral vectors expressing double-floxed Cre-dependent Gαq-coupled human M3 muscarinic receptor DREADD (hM3D)-mCherry or Gαi-coupled κ-opioid receptor DREADD (KORD)-IRES-mCitrine were microinjected into the superficial spinal dorsal horn of VGluT2-Cre mice. Immunofluorescence labeling showed that VGluT2 was predominantly expressed in lamina II excitatory interneurons. Activation of excitatory hM3D in VGluT2-expressing neurons with clozapine N-oxide caused a profound increase in neuronal firing and synaptic glutamate release. Conversely, activation of inhibitory KORD in VGluT2-expressing neurons with salvinorin B markedly inhibited neuronal activity and synaptic glutamate release. In addition, chemogenetic stimulation of VGluT2-expressing neurons increased mechanical and thermal sensitivities in naive mice, whereas chemogenetic silencing of VGluT2-expressing neurons reversed pain hypersensitivity induced by tissue inflammation and peripheral nerve injury. These findings indicate that VGluT2-expressing excitatory neurons play a crucial role in mediating nociceptive transmission in the spinal dorsal horn. Targeting glutamatergic dorsal horn neurons with inhibitory DREADDs may be a new strategy for treating inflammatory pain and neuropathic pain.

Seventy-eight isolates of avian infectious bronchitis virus (IBV) were obtained from different field outbreaks in China in 2009 and genotyped with 34 reference strains. Four genotypes of IBV and three new isolates were identified by phylogenetic analysis and BLAST searches of the entire S1 gene. The results showed that most IBV strains that have circulated in China in recent years belong to the genotype of QX-like strains, and that they could be grouped further into two clusters, regardless of the level of genetic variation displayed. A study of pathogenicity that used three QX-like strains*ck/CH/LSD/091003, ck/CH/LDL/091022 and ck/CH/LJL/ 090330*showed that the isolates caused the most severe lesions in the kidneys and were therefore nephropathogenic strains with various levels of virulence in specific pathogen free chickens. A vaccinationÁ challenge test that was performed using the three QX-like strains showed that the commercially available H120 vaccine did not provide sufficient protection against challenge with the QX-like isolates, as demonstrated by comparison of the clinical signs, pathological lesions and virus recovery from the trachea and kidney of unvaccinatedÁchallenged and vaccinatedÁchallenged birds.

Type 2 diabetes mellitus (T2DM) is a multifactorial disease, and its aetiology involves a complex interplay between genetic, epigenetic, and environmental factors. In recent years, evidences from both human and animal experiments have correlated early life factors with programming diabetes risk in adult life. Fetal and neonatal period is crucial for organ development. Many maternal factors during pregnancy may increase the risk of diabetes of offsprings in later life, which include malnutrition, healthy (hyperglycemia and obesity), behavior (smoking, drinking, and junk food diet), hormone administration, and even stress. In neonates, catch-up growth, lactation, glucocorticoids administration, and stress have all been found to increase the risk of insulin resistance or T2DM. Unfavorable environments (socioeconomic situation and famine) or obesity also has long-term negative effects on children by causing increased susceptibility to T2DM in adults. We also address the potential mechanisms that may underlie the developmental programming of T2DM. Therefore, it might be possible to prevent or delay the risk for T2DM by improving pre- and/or postnatal factors.