Molecular and cellular neurosciences
-
Mol. Cell. Neurosci. · May 2014
Intraneural convection enhanced delivery of AAVrh20 for targeting primary sensory neurons.
Gene therapy using adeno-associated virus (AAV) is an attractive strategy to treat disorders of the peripheral nervous system (PNS), such as chronic pain or peripheral neuropathies. Although intrathecal (IT) administration of AAV has been the standard in the field for targeting the PNS, it lacks anatomical specificity and results in wide rostro-caudal distribution of the vector. An alternative approach is to deliver AAV directly to the peripheral nerve axon. ⋯ AAVrh20 was superior to reference serotypes previously described to be most active for each route. Intraneural CED of AAV was associated with transient allodynia that resolved spontaneously. These findings establish intraneural CED as an alternative to IT administration for AAV mediated gene transfer to the PNS and, based on a reference rodent model, suggest AAVrh20 as a superior serotype for targeting the PNS.
-
Mol. Cell. Neurosci. · May 2014
Dynorphin up-regulation in the dentate granule cell mossy fiber pathway following chronic inhibition of GluN2B-containing NMDAR is associated with increased CREB (Ser 133) phosphorylation, but is independent of BDNF/TrkB signaling pathways.
Emerging evidence suggests that neuronal responses to N-methyl-d-aspartate (NMDAR) activation/inactivation are influenced by subunit composition. For example, activation of synaptic NMDAR (comprised of GluN2A>GluN2B) phosphorylates cAMP-response-element-binding protein (CREB) at Ser 133, induces BDNF expression and promotes neuronal survival. Activation of extrasynaptic NMDAR (comprised of GluN2B>GluN2) dephosphorylates CREB (Ser 133), reduces BDNF expression and triggers neuronal death. ⋯ In contrast to our hypothesis, BDNF levels were decreased following chronic treatment with Ro25,6981, but not ifenprodil, d-APV or memantine. Blockade of BDNF actions and TrkB activation did not significantly augment hilar DYN expression in vehicle-treated cultures and had no effect in Ro25,6981 treated cultures. These findings suggest that chronic exposure to GluN2B-selective NMDAR antagonists increased DYN expression through a putatively pCREB-dependent, but BDNF/TrkB-independent mechanism.
-
Mol. Cell. Neurosci. · May 2014
Over-expression of astrocytic ET-1 attenuates neuropathic pain by inhibition of ERK1/2 and Akt(s) via activation of ETA receptor.
A differential role of endothelin-1 (ET-1) in pain processing has recently been suggested. However, the function of central ET-1 in neuropathic pain (NP) has not been fully elucidated to date. We report here the action of endogenous central ET-1 in sciatic nerve ligation-induced NP (SNL-NP) in a transgenic animal model that over-expresses ET-1 in the astrocytes (GET-1 mice). ⋯ The effects of BQ-123 on the mRNA expression of extracellular signal-regulated protein kinase 1/2 (ERK1/2) and protein kinase B/serine protein kinase (Akt(s)) were assessed in the ipsilateral L4-L6 segments harvested 30min after BQ-123 administration on day 7 after surgery. Phosphorylation of ERK1/2 and Akt(s) in the ipsilateral spinal cord of GET-1 mice was reduced following SNL, whereas no reduction was observed after intrathecal injection of BQ-123. In conclusion, our results showed that the xover-expression of astrocytic ET-1 reduced SNL-induced allodynia and hyperalgesia by inhibiting the activation of ERK1/2 and Akt(s) via the ETA-R-mediated pathway.
-
Mol. Cell. Neurosci. · May 2014
Temporal alterations in aquaporin and transcription factor HIF1α expression following penetrating ballistic-like brain injury (PBBI).
Brain edema is a primary factor in the morbidity and mortality of traumatic brain injury (TBI). The various isoforms of aquaporin 4 (AQP4) and aquaporin 9 (AQP9) are important factors influencing edema following TBI. Others have reported that these AQPs are regulated by the transcription factor hypoxia inducible factor (HIF) 1α. Therefore, we examined the temporal alterations in the multiple isoforms of AQP4 and AQP9, and its possible upstream regulation by HIF1α, and evaluated whether different severities of penetrating injury influence these mechanisms. ⋯ PBBI is characterized by a loss of AQP4 M1, AQP4 isoform 3 and AQP9 at delayed time-points. The severity of the injury (PBBI versus probe control) increased these effects. Therefore, AQP9 and the AQP4 M1 isoform may be regulated by HIF1α, but not AQP4 isoform 3. This delayed loss of aquaporins may markedly reduce the ability of the brain to efflux water, contributing to the protracted edema that is a characteristic following severe penetrating TBI. Factors contributing to edema differ with different types and severities of TBI. For example, cellular based edema is more prominent in diffuse non-penetrating TBI whereas vasogenic edema is more prevalent with TBI involving hemorrhage. Molecular regulation leading to edema will likely also differ, such that treatments which have been suggested for non-hemorrhagic moderate TBI, such as the suppression of aquaporins, may be detrimental in more severe forms of TBI.