Snapshots in Neuroscience: Mouse Brain

This image has been selected to showcase the art that neuroscience research can create.

As described by Dr. Brigitte Kieffer and colleagues: Neurons responding to medicinal and abused opioids are visualized for the first time in the mouse brain.

Opioid drugs produce their strong pain killing and addictive effects by activating mu opioid receptors (MORs) in the brain. We have created an Oprm1-Cre knock-in mouse line expressing the Cre recombinase at the MOR gene locus. The enzyme is therefore expressed in every neuron that expresses MOR and normally responds to opioid drugs. We have crossed these mice with Cre-dependent reporter Rosa^lsltdTomatomice, and obtained a new line, where all the MOR-positive neurons are filled-up with strong red fluorescence. This image shows a whole brain sagittal view, revealing intensely labeled cell bodies and processes in neurons of the thalamus, of the entire mesolimbic pathway including the ventral tegmental area/substantia nigra projecting to striatal patches, a well as discrete neurons throughout cortical and cerebellar layers.

All these neurons are first-in-line cellular targets for oxycodone, morphine, fentanyl, heroin and other opioids, and adapt to chronic exposure to these drugs leading to addiction and the current opioid crisis. This novel Oprm1-Cre knock-in mouse line will allow brain mapping, molecular phenotyping, and opto/chemogenetic manipulations of opioid-responsive neurons, and will be of broad interest for opioid, pain, reward and addiction research.

Read the full article:

Targeting Morphine-Responsive Neurons: Generation of a Knock-In Mouse Line Expressing Cre Recombinase from the Mu-Opioid Receptor Gene Locus
Julie Bailly, Natalie Del Rossi, Léonie Runtz, Jing-Jing Li, DaWoon Park, Grégory Scherrer, Arnaud Tanti, Marie-Christine Birling, Emmanuel Darcq, and Brigitte L. Kieffer