title: Differential effects of exercise on brain opioid receptor binding and activation in rats.
abstract: Physical exercise stimulates the release of endogenous opioid peptides supposed to be responsible for changes in mood, anxiety, and performance. Exercise alters sensitivity to these effects that modify the efficacy at the opioid receptor. Although there is evidence that relates exercise to neuropeptide expression in the brain, the effects of exercise on opioid receptor binding and signal transduction mechanisms downstream of these receptors have not been explored. Here, we characterized the binding and G protein activation of mu opioid receptor, kappa opioid receptor or delta opioid receptor in several brain regions following acute (7 days) and chronic (30 days) exercise. As regards short- (acute) or long-term effects (chronic) of exercise, overall, higher opioid receptor binding was observed in acute-exercise animals and the opposite was found in the chronic-exercise animals. The binding of [(35) S]GTPγS under basal conditions (absence of agonists) was elevated in sensorimotor cortex and hippocampus, an effect more evident after chronic exercise. Divergence of findings was observed for mu opioid receptor, kappa opioid receptor, and delta opioid receptor receptor activation in our study. Our results support existing evidence of opioid receptor binding and G protein activation occurring differentially in brain regions in response to diverse exercise stimuli. We characterized the binding and G protein activation of mu, kappa, and delta opioid receptors in several brain regions following acute (7 days) and chronic (30 days) exercise. Higher opioid receptor binding was observed in the acute exercise animal group and opposite findings in the chronic exercise group. Higher G protein activation under basal conditions was noted in rats submitted to chronic exercise, as visible in the depicted pseudo-color autoradiograms.
authors.affiliation: Departamento de Fisiologia, Universidade Federal de São Paulo/Escola Paulista de Medicina (UNIFESP/EPM), São Paulo, SP, Brazil.
authors.forename: Ricardo Mario
authors.initials: RM
authors.lastname: Arida
authors.forename: Sérgio
authors.initials: S
authors.lastname: Gomes da Silva
authors.forename: Alexandre Aparecido
authors.initials: AA
authors.lastname: de Almeida
authors.forename: Esper Abrão
authors.initials: EA
authors.lastname: Cavalheiro
authors.forename: Cecilia
authors.initials: C
authors.lastname: Zavala-Tecuapetla
authors.forename: Serge
authors.initials: S
authors.lastname: Brand
authors.forename: Luisa
authors.initials: L
authors.lastname: Rocha
mesh_terms: D000679:Amygdala / Q000378:metabolism; D000818:Animals; D044482:Benzeneacetamides / Q000378:metabolism; D001923:Brain Chemistry; D002540:Cerebral Cortex / Q000378:metabolism; D004597:Electroshock; D020881:Enkephalin, D-Penicillamine (2,5)- / Q000378:metabolism; D004789:Enzyme Activation; D019204:GTP-Binding Proteins / Q000378:metabolism; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000378:metabolism; D006624:Hippocampus / Q000378:metabolism; D007031:Hypothalamus / Q000378:metabolism; D009270:Naloxone / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism; D018847:Opioid Peptides / Q000378:metabolism; D010805:Physical Conditioning, Animal; D011485:Protein Binding; D011759:Pyrrolidines / Q000378:metabolism; D051381:Rats; D011957:Receptors, Opioid / Q000378:metabolism*; D015398:Signal Transduction; D013997:Time Factors
chemical_list: D044482:Benzeneacetamides; D009419:Nerve Tissue Proteins; D018847:Opioid Peptides; D011759:Pyrrolidines; D011957:Receptors, Opioid; D009270:Naloxone; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D020881:Enkephalin, D-Penicillamine (2,5)-; D019204:GTP-Binding Proteins; C045444:U 69593
keywords: DOR; KOR; MOR; brain; exercise; opioid receptor