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- Hussain, Zubair Muhammad, et al.
(författare)
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Lateralized Response of Dynorphin A Peptide Levels after Traumatic Brain Injury
- 2012
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Ingår i: Journal of Neurotrauma. - : Mary Ann Liebert Inc. - 0897-7151 .- 1557-9042. ; 29:9, s. 1785-1793
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Tidskriftsartikel (refereegranskat)abstract
- Traumatic brain injury (TBI) induces a cascade of primary and secondary events resulting in impairment of neuronal networks that eventually determines clinical outcome. The dynorphins, endogenous opioid peptides, have been implicated in secondary injury and neurodegeneration in rodent and human brain. To gain insight into the role of dynorphins in the brain's response to trauma, we analyzed short-term (1-day) and long-term (7-day) changes in dynorphin A (Dyn A) levels in the frontal cortex, hippocampus, and striatum, induced by unilateral left-side or right-side cortical TBI in mice. The effects of TBI were significantly different from those of sham surgery (Sham), while the sham surgery also produced noticeable effects. Both sham and TBI induced short-term changes and long-term changes in all three regions. Two types of responses were generally observed. In the hippocampus, Dyn A levels were predominantly altered ipsilateral to the injury. In the striatum and frontal cortex, injury to the right (R) hemisphere affected Dyn A levels to a greater extent than that seen in the left (L) hemisphere. The R-TBI but not L-TBI produced Dyn A changes in the striatum and frontal cortex at 7 days after injury. Effects of the R-side injury were similar in the two hemispheres. In naive animals, Dyn A was symmetrically distributed between the two hemispheres. Thus, trauma may reveal a lateralization in the mechanism mediating the response of Dyn A-expressing neuronal networks in the brain. These networks may differentially mediate effects of left and right brain injury on lateralized brain functions.
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- Watanabe, Hiroyuki, et al.
(författare)
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Asymmetry of the Endogenous Opioid System in the Human Anterior Cingulate : a Putative Molecular Basis for Lateralization of Emotions and Pain
- 2015
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Ingår i: Cerebral Cortex. - United kingdom : Oxford University Press (OUP). - 1047-3211 .- 1460-2199. ; 25:1, s. 97-108
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Tidskriftsartikel (refereegranskat)abstract
- Lateralization of processing of positive and negative emotions and pain suggests an asymmetric distribution of the neurotransmitter systems regulating these functions between the left and right brain hemispheres. By virtue of their ability to selectively mediate euphoria, dysphoria and pain, the m-, d- and k-opioid receptors and their endogenous ligands may subserve these lateralized functions. We addressed this hypothesis by comparing the levels of the opioid receptors and peptides in the left and right anterior cingulate cortex (ACC), a key area for emotion and pain processing. Opioid mRNAs and peptides and five “classical” neurotransmitters were analyzed in postmortem tissues from 20 human subjects. Leu-enkephalin-Arg and Met-enkephalin-Arg-Phe, preferential d-/m- and k-/m-opioid agonists demonstrated marked lateralization to the left and right ACC, respectively. Dynorphin B strongly correlated with Leu-enkephalin-Arg in the left but not right ACC suggesting different mechanisms of conversion of this k-opioid agonist to d-/m-opioid ligand in the two hemispheres; in the right ACC dynorphin B may be cleaved by PACE4, a proprotein convertase regulating left-right asymmetry formation. These findings suggest that region-specific lateralization of neuronal networks expressing opioid peptides underlyes in part lateralization of higher functions including positive and negative emotions and pain in the human brain.
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