Neuroscience
-
Despite increasingly widespread use of recombinant adeno-associated virus (AAV) and lentiviral (LV) vectors for transduction of neurons in a wide range of brain structures and species, the diversity of cell types within a given brain structure is rarely considered. For example, the ability of a vector to transduce neurons within a brain structure is often assumed to indicate that all neuron types within the structure are transduced. We have characterized the transduction of mouse somatosensory cortical neuron types by recombinant AAV pseudotyped with serotype 1 capsid (rAAV2/1) and by recombinant lentivirus pseudotyped with the vesicular stomatitis virus (VSV) glycoprotein. ⋯ We demonstrate that high titer rAAV2/1-hSyn efficiently transduces both cortical excitatory and inhibitory neuronal populations, but use of lower titers exposes a strong preference for transduction of cortical inhibitory neurons and layer 5 pyramidal neurons. In contrast, we find that VSV-G-LV-hSyn principally labels excitatory cortical neurons at the highest viral titer generated. These findings demonstrate that endogenous tropism of rAAV2/1 and VSV-G-LV can be used to obtain preferential gene expression in mouse somatosensory cortical inhibitory and excitatory neuron populations, respectively.
-
Our previous finding, that the capsaicin- and KCl-induced Ca(2+)-dependent production of the intra- and intercellular signaling molecule N-arachidonoyl ethanolamine (anandamide) in cultured primary sensory neurons could be abolished and reduced by approximately 2/3 by capsaicin-induced degeneration of capsaicin-sensitive neurons, respectively suggests that a major sub-population of capsaicin-sensitive cells together with a group of non-capsaicin-sensitive cells should express enzymes involved in Ca(2+)-dependent anandamide synthesis. N-acyl phosphotidylethanolamine phospholipase D (NAPE-PLD) is known to be involved in Ca(2+)-dependent anandamide production. Hence, here, we used reverse transcriptase and quantitative real time polymerase chain reaction to study NAPE-PLD expression in dorsal root ganglia and to clarify the sub-population of cells expressing this enzyme. ⋯ Furthermore, we also report that capsaicin application downregulates the expression of NAPE-PLD as well as the capsaicin receptor, transient receptor potential vanilloid type 1 ion channel, by about 70% in the cultures prepared from dorsal root ganglia. These findings indicate that a major sub-population of capsaicin-sensitive primary sensory neurons expresses NAPE-PLD, and suggest that NAPE-PLD is expressed predominantly by capsaicin-sensitive neurons in dorsal root ganglia. These data also suggest that NAPE-PLD might be a target to control the activity and excitability of a major sub-population of nociceptive primary sensory neurons.
-
The role of chemokines in immune function is clearly established. Recent evidence suggests that these molecules also play an important role in the central nervous system as modulators of neuronal activity. The chemokine CXCL12 has been identified in several regions of the adult rat brain including the substantia nigra, ventral tegmental area and caudate putamen. ⋯ Conversely, administration of CXCL12 into the lateral shell of the nucleus accumbens resulted in an inhibition of cocaine-stimulated ambulatory activity. No alterations in ambulatory or stereotypic activity were observed following CXCL12 administration into the core of the nucleus accumbens. These results demonstrate that CXCL12 can modulate the behavioral effects produced by cocaine in a brain region-specific manner.
-
Fas-associated protein with death domain (FADD) is a multifunctional protein that can induce both apoptotic and non-apoptotic actions. Recently, FADD was found downregulated in the prefrontal cortex of opiate abusers, which suggested an attenuation of Fas death signals in human addicts. Phosphorylation of FADD (Ser194) has been reported to regulate its non-apoptotic activity, which might include the induction of neuroplastic effects in the brain. ⋯ Similarly, the signaling pathway mediated by p-phosphoprotein enriched in astrocytes of 15 kDa (PEA-15) protein and its phosphorylating kinase p-Akt1 was also downregulated in cortical homogenate (43% and 41%, respectively) and cytosolic preparations of chronic opiate addicts. The results indicate that opiate addiction in humans is associated with an altered balance between p-Ser194 FADD (increased) and total FADD (decreased) in brain, which may favor its neuroplastic actions. The interaction between p-FADD (upregulated) and neuronal pathways (downregulated) could play a relevant role in mediating specific forms of structural and behavioral neuroplasticity.
-
In Drosophila, mushroom bodies are centers for higher order behavior. Mushroom body neurons consist of three distinct types of neuronal cells, alpha, alpha'/beta', and alpha/beta, which are all generated by the same neuroblasts. ⋯ Reduced bun expression causes decreased and premature arrest of neuroblast cell division, which results in reduced numbers of alpha/beta neurons and thin axon bundled formation. We propose that bun acts as a specific factor in regulating neuroblast mitotic activity during the development of alpha/beta neurons.