Overexpression of Protein Kinase Inhibitor Alpha Reverses Rat Low Voluntary Running Behavior
A gene was sought that could reverse low voluntary running distances in a model of low voluntary wheel-running behavior. In order to confirm the low motivation to wheel-run in our model does not result from defects in reward valuation, we employed sucrose preference and conditioned place preference for voluntary wheel-access. We observed no differences between our model and wild-type rats regarding the aforementioned behavioral testing. Instead, low voluntary runners seemed to require less running to obtain similar rewards for low voluntary running levels compared to wild-type rats. Previous work in our lab identified protein kinase inhibitor alpha as being lower in low voluntary running than wild-type rats. Next, nucleus accumbens injections of an adenoviral-associated virus that overexpressed the protein kinase inhibitor alpha gene increased running distance in low voluntary running, but not wild-type rats. Endogenous mRNA levels for protein kinase inhibitor alpha, dopamine receptor D1, dopamine receptor D2, and Fos were all only lower in wild-type rats following overexpression compared to low voluntary runners, suggesting a potential molecular and behavioral resistance in wild-type rats. Utilizing a nucleus accumbens preparation, three intermediate early gene mRNAs increased in low voluntary running slices after dopamine receptor agonist SKF-38393 exposure, while wild-type had no response. In summary, the results suggest that protein kinase inhibitor alpha is a promising gene candidate to partially rescue physical activity in the polygenic model of low voluntary running. Importantly, there were divergent molecular responses to protein kinase inhibitor alpha overexpression in low voluntary runners compared to wild-type rats.
KeywordsBehavior Gene Brain Rescue Voluntary running Selective breeding
The authors would like to thank Dr. Cathleen Kovarik for the generous use of her laboratory. We are also grateful to and would like to acknowledge Dr. Tyler Jacks and Dr. Alexander Dent for their gifting of plasmids used in this study.
The study was funded by the University of Missouri.
Compliance with Ethical Standards
Conflicts of Interest
The authors declare that they have no conflict of interest.
- 5.Roberts MD, Brown JD, Company JM, et al (2013) Phenotypic and molecular differences between rats selectively bred to voluntarily run high vs. low nightly distances. AJP Regul Integr Comp Physiol 304:R1024–R1035. doi: https://doi.org/10.1152/ajpregu.00581.2012 CrossRefPubMedPubMedCentralGoogle Scholar
- 7.Ruegsegger GN, Brown JD, Kovarik MC, Miller DK, Booth FW (2016) Mu-opioid receptor inhibition decreases voluntary wheel running in a dopamine-dependent manner in rats bred for high voluntary running. Neuroscience 339:525–537. https://doi.org/10.1016/j.neuroscience.2016.10.020 CrossRefPubMedGoogle Scholar
- 17.Roberts MD, Toedebusch RG, Wells KD, Company JM, Brown JD, Cruthirds CL, Heese AJ, Zhu C et al (2014) Nucleus accumbens neuronal maturation differences in young rats bred for low versus high voluntary running behaviour. J Physiol 592:2119–2135. https://doi.org/10.1113/jphysiol.2013.268805 CrossRefPubMedPubMedCentralGoogle Scholar
- 19.Chen X, Dai JC, Orellana SA, Greenfield EM (2005) Endogenous protein kinase inhibitor γ terminates immediate-early gene expression induced by cAMP-dependent protein kinase (PKA) signaling: Termination depends on PKA inactivation rather than PKA export from the nucleus. J Biol Chem 280:2700–2707. https://doi.org/10.1074/jbc.M412558200 CrossRefPubMedGoogle Scholar
- 25.Hyatt HW, Toedebusch RG, Ruegsegger G, Mobley CB, Fox CD, McGinnis GR, Quindry JC, Booth FW et al (2015) Comparative adaptations in oxidative and glycolytic muscle fibers in a low voluntary wheel running rat model performing three levels of physical activity. Physiol Rep 3:e12619. https://doi.org/10.14814/phy2.12619 CrossRefPubMedPubMedCentralGoogle Scholar
- 26.Grigsby KB, Kovarik CM, Rottinghaus GE, Booth FW (2018) High and low nightly running behavior associates with nucleus accumbens N-methyl-D-aspartate receptor (NMDAR) NR1 subunit expression and NMDAR functional differences. Neurosci Lett 671:50–55. https://doi.org/10.1016/j.neulet.2018.02.011 CrossRefPubMedGoogle Scholar
- 29.Paxinos G, Watson C (1997) The Rat Brain in Stereotaxic Coordinates. Acad Press San Diego 3rd ed:Google Scholar
- 34.Vasanwala FH, Kusam S, Toney LM, Dent AL (2002) Repression of AP-1 function: a mechanism for the regulation of Blimp-1 expression and B lymphocyte differentiation by the B cell lymphoma-6 protooncogene. J Immunol 169:1922–1929. https://doi.org/10.4049/jimmunol.169.4.1922 CrossRefPubMedGoogle Scholar
- 40.Smith-Roe SL, Kelley AE (2000) Coincident activation of NMDA and dopamine D1 receptors within the nucleus accumbens core is required for appetitive instrumental learning. J Neurosci 20:7737–7742. doi: 20/20/7737 [pii]Google Scholar
- 41.Ruegsegger GN, Grigsby KB, Kelty TJ, Zidon TM, Childs TE, Vieira-Potter VJ, Klinkebiel DL, Matheny M et al (2017) Maternal western diet age-specifically alters female offspring voluntary physical activity and dopamine- and leptin-related gene expression. FASEB J 31:5371–5383. https://doi.org/10.1096/fj.201700389R CrossRefPubMedGoogle Scholar
- 44.Carr GD, Fibiger HC, Phillips AG (1989) Conditioned place preference as a measure of drug reward. In: The neuropharmacological basis of reward. Topics in experimental psychopharmacology. pp 264–319.Google Scholar
- 48.Duclot F, Kabbaj M (2017) The role of early growth response 1 (EGR1) in brain plasticity and neuropsychiatric disorders. Front Behav Neurosci 11. https://doi.org/10.3389/fnbeh.2017.00035
- 49.Girault JA (2012) Signaling in striatal neurons: the phosphoproteins of reward, addiction, and dyskinesia. Prog Mol Biol Transl Sci 106:33–62. doi: https://doi.org/10.1016/B978-0-12-396456-4.00006-7 Google Scholar
- 55.Self DW, Genova LM, Hope BT et al (1998) Involvement of cAMP-dependent protein kinase in the nucleus accumbens in cocaine self-administration and relapse of cocaine-seeking behavior. J Neurosci 18:1848–1859. https://doi.org/10.1523/JNEUROSCI.18-05-01848.1998 CrossRefPubMedGoogle Scholar
- 57.Barrot M, Olivier JDA, Perrotti LI, DiLeone RJ, Berton O, Eisch AJ, Impey S, Storm DR et al (2002) CREB activity in the nucleus accumbens shell controls gating of behavioral responses to emotional stimuli. Proc Natl Acad Sci 99:11435–11440. https://doi.org/10.1073/pnas.172091899 CrossRefPubMedGoogle Scholar