Neurophysiological evidence for the presence of cannabinoid CB1 receptors in the laterodorsal tegmental nucleus.
Neeraj Soni, Shankha Satpathy, Kristi A. Kohlmeier
European Journal of Neuroscience December 2014 DOI: 10.1111/ejn.12730 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Electrophysiological study in mouse brain slices Peer reviewed |
|---|---|
| Population | Mouse brain slices (laterodorsal tegmental nucleus neurons) |
| Interventions | WIN-2 AM251 |
| Keywords | Arousal Cholinergic Electrophysiology Endocannabinoids Synaptic transmission |
| Key points | The CB1R agonist WIN-2 decreased the frequency of spontaneous and miniature inhibitory postsynaptic currents and reduced firing frequency of LDT neurons, while the CB1R antagonist AM251 increased sIPSCs, indicating ongoing endogenous endocannabinoid activity. The authors conclude that CB1 receptors are functionally active in the LDT and that endogenous endocannabinoid transmission may play a role in LDT-related processes such as cortical activation and motivated behaviors. |
Abstract
Marijuana, which acts within the endocannabinoid (eCB) system as an agonist of the cannabinoid type 1 receptor (CB1R), exhibits addictive properties and has powerful actions on the state of arousal of an organism. The laterodorsal tegmental nucleus (LDT), as a component of the reticular activating system, is involved in cortical activation and is important in the development of drug addiction-associated behaviours. Therefore, eCBs might exert behavioural effects by actions on the LDT; however, it is unknown whether eCBs have actions on neurons in this nucleus. Accordingly, whole-cell voltage- and current-clamp recordings were conducted from mouse brain slices, and responses of LDT neurons to the CB1R agonist WIN-2 were monitored. Our results showed that WIN-2 decreased the frequency of spontaneous and miniature inhibitory postsynaptic currents (sIPSCs and mIPSCs). Ongoing activity of endogenous eCBs was confirmed as AM251, a potent CB1R antagonist, elicited sIPSCs. WIN-2 reduced the firing frequency of LDT neurons. In addition, our RT-PCR studies confirmed the presence of CB1R transcript in the LDT. Taken together, we conclude that CB1Rs are functionally active in the LDT, and their activation changes the firing frequency and synaptic activity of neurons in this nucleus. Therefore, endogenous eCB transmission could play a role in processes involving the LDT, such as cortical activation and motivated behaviours and, further, behavioural actions of marijuana are probably mediated, in part, via cellular actions within the LDT induced by this addictive and behavioural state-altering drug.