Margaret K Tanner1, Jazmyne K P Davis1, Jennifer Jaime1,2, Nicolette A Moya1,3, Alyssa A Hohorst1, Kelsey Bonar1, Kelsey A Abrams1,4, Nashra Jamil1, Rebecca Han1, Troy J Hubert1,5, Nadja Brown1, Esteban C Loetz1, Benjamin N Greenwood6. 1. Department of Psychology, University of Colorado Denver, PO Box 173364, North Classroom Rm. 5005 F, CB 173, Denver, CO, 80217-3364, USA. 2. Neuroscience Graduate Program, University of Michigan Medical School, Ann Arbor, MI, 48109, USA. 3. Department of Neuroscience, Northwestern Feinberg School of Medicine, Chicago, IL, 60611, USA. 4. University of Colorado Anschutz Medical Campus, Cell Biology, Stem Cells, and Development Graduate Program, Aurora, CO, USA. 5. Department of Psychology, University of Kentucky, Lexington, KY, 40506, USA. 6. Department of Psychology, University of Colorado Denver, PO Box 173364, North Classroom Rm. 5005 F, CB 173, Denver, CO, 80217-3364, USA. benjamin.greenwood@ucdenver.edu.
Abstract
RATIONALE: Exercise participation remains low despite clear benefits. Rats engage in voluntary wheel running (VWR) that follows distinct phases of acquisition, during which VWR escalates, and maintenance, during which VWR remains stable. Understanding mechanisms driving acquisition and maintenance of VWR could lead to novel strategies to promote exercise. The two phases of VWR resemble those that occur during operant conditioning and, therefore, might involve similar neural substrates. The dorsomedial (DMS) dorsal striatum (DS) supports the acquisition of operant conditioning, whereas the dorsolateral striatum (DLS) supports its maintenance. OBJECTIVES: Here we sought to characterize the roles of DS subregions in VWR. Females escalate VWR and operant conditioning faster than males. Thus, we also assessed for sex differences. METHODS: To determine the causal role of DS subregions in VWR, we pharmacologically inactivated the DMS or DLS of adult, male and female, Long-Evans rats during the two phases of VWR. The involvement of DA receptor 1 (D1)-expressing neurons in the DS was investigated by quantifying cfos mRNA within this neuronal population. RESULTS: We observed that, in males, the DMS and DLS are critical for VWR exclusively during acquisition and maintenance, respectively. In females, the DMS is also critical only during acquisition, but the DLS contributes to VWR during both VWR phases. DLS D1 neurons could be an important driver of VWR escalation during acquisition. CONCLUSIONS: The acquisition and maintenance of VWR involve unique neural substrates in the DS that vary by sex. Results reveal targets for sex-specific strategies to promote exercise.
RATIONALE: Exercise participation remains low despite clear benefits. Rats engage in voluntary wheel running (VWR) that follows distinct phases of acquisition, during which VWR escalates, and maintenance, during which VWR remains stable. Understanding mechanisms driving acquisition and maintenance of VWR could lead to novel strategies to promote exercise. The two phases of VWR resemble those that occur during operant conditioning and, therefore, might involve similar neural substrates. The dorsomedial (DMS) dorsal striatum (DS) supports the acquisition of operant conditioning, whereas the dorsolateral striatum (DLS) supports its maintenance. OBJECTIVES: Here we sought to characterize the roles of DS subregions in VWR. Females escalate VWR and operant conditioning faster than males. Thus, we also assessed for sex differences. METHODS: To determine the causal role of DS subregions in VWR, we pharmacologically inactivated the DMS or DLS of adult, male and female, Long-Evans rats during the two phases of VWR. The involvement of DA receptor 1 (D1)-expressing neurons in the DS was investigated by quantifying cfos mRNA within this neuronal population. RESULTS: We observed that, in males, the DMS and DLS are critical for VWR exclusively during acquisition and maintenance, respectively. In females, the DMS is also critical only during acquisition, but the DLS contributes to VWR during both VWR phases. DLS D1 neurons could be an important driver of VWR escalation during acquisition. CONCLUSIONS: The acquisition and maintenance of VWR involve unique neural substrates in the DS that vary by sex. Results reveal targets for sex-specific strategies to promote exercise.