BACKGROUND: We have shown that the endogenous stimulation of cannabinoid type-1 (CB₁) receptors is a prerequisite for voluntary running in mice, but the precise mechanisms through which the endocannabinoid system exerts a tonic control on running performance remain unknown. METHODS: We analyzed the respective impacts of constitutive/conditional CB₁ receptor mutations and of CB₁ receptor blockade on wheel-running performance. We then assessed the consequences of ventral tegmental area (VTA) CB₁ receptor blockade on the wheel-running performances of wildtype (gamma-aminobutyric acid [GABA]-CB₁⁺/⁺) and mutant (GABA-CB₁⁻/⁻) mice for CB₁ receptors in brain GABA neurons. Using in vivo electrophysiology, the consequences of wheel running on VTA dopamine (DA) neuronal activity were examined in GABA-CB₁⁺/⁺ and GABA-CB₁⁻/⁻ mice. RESULTS: Conditional deletion of CB₁ receptors from brain GABA neurons, but not from several other neuronal populations or from astrocytes, decreased wheel-running performance in mice. The inhibitory consequences of either the systemic or the intra-VTA administration of CB1 receptor antagonists on running behavior were abolished in GABA-CB₁⁻/⁻ mice. The absence of CB1 receptors from GABAergic neurons led to a depression of VTA DA neuronal activity after acute/repeated wheel running. CONCLUSIONS: This study provides evidence that CB₁ receptors on VTA GABAergic terminals exert a permissive control on rodent voluntary running performance. Furthermore, it is shown that CB₁ receptors located on GABAergic neurons impede negative consequences of voluntary exercise on VTA DA neuronal activity. These results position the endocannabinoid control of inhibitory transmission as a prerequisite for wheel-running performance in mice.
BACKGROUND: We have shown that the endogenous stimulation of cannabinoid type-1 (CB₁) receptors is a prerequisite for voluntary running in mice, but the precise mechanisms through which the endocannabinoid system exerts a tonic control on running performance remain unknown. METHODS: We analyzed the respective impacts of constitutive/conditional CB₁ receptor mutations and of CB₁ receptor blockade on wheel-running performance. We then assessed the consequences of ventral tegmental area (VTA) CB₁ receptor blockade on the wheel-running performances of wildtype (gamma-aminobutyric acid [GABA]-CB₁⁺/⁺) and mutant (GABA-CB₁⁻/⁻) mice for CB₁ receptors in brain GABA neurons. Using in vivo electrophysiology, the consequences of wheel running on VTA dopamine (DA) neuronal activity were examined in GABA-CB₁⁺/⁺ and GABA-CB₁⁻/⁻ mice. RESULTS: Conditional deletion of CB₁ receptors from brain GABA neurons, but not from several other neuronal populations or from astrocytes, decreased wheel-running performance in mice. The inhibitory consequences of either the systemic or the intra-VTA administration of CB1 receptor antagonists on running behavior were abolished in GABA-CB₁⁻/⁻ mice. The absence of CB1 receptors from GABAergic neurons led to a depression of VTA DA neuronal activity after acute/repeated wheel running. CONCLUSIONS: This study provides evidence that CB₁ receptors on VTA GABAergic terminals exert a permissive control on rodent voluntary running performance. Furthermore, it is shown that CB₁ receptors located on GABAergic neurons impede negative consequences of voluntary exercise on VTA DA neuronal activity. These results position the endocannabinoid control of inhibitory transmission as a prerequisite for wheel-running performance in mice.
Authors: Carrie E Mahoney; Lindsay J Agostinelli; Jessica N K Brooks; Bradford B Lowell; Thomas E Scammell Journal: J Neurosci Date: 2017-02-24 Impact factor: 6.167
Authors: Johannes Fuss; Jörg Steinle; Laura Bindila; Matthias K Auer; Hartmut Kirchherr; Beat Lutz; Peter Gass Journal: Proc Natl Acad Sci U S A Date: 2015-10-05 Impact factor: 11.205