Validation of a transgenic mouse line with knock down of mGluR5 selectively in dopamine D1 receptor expressing neurons

One of the main difficulties of addiction treatment is the high risk of relapse even after a long abstinence and fully detoxification. Therefore, discovering the underlying molecular principles of relapse is essential. The metabotropic glutamate receptor, mGluR5, is considered to be involved in this aspect. One of the brain structures expressing mGluR5 is the striatum, an area with well-established role in addiction which is largely composed of medium-sized spiny neurons (MSNs). These neurons are basically divided into two major subpopulations characterized based on their projections and protein properties. It is known that the mGluR5 receptor is expressed on both subpopulations of MSNs. Consequently, it can be used to establish the proportional contribution of each of MSNs subpopulations in relapse to addiction. In our constellation, we have generated a mouse line designed to have a selective mGluR5 knock-down in one of these subpopulations – the dopamine D1 receptor (D1R) expressing neurons. It has however been unclear if the expression of the transgene is indeed limited to only D1R-expressing neurons. By immunofluorescence technique, I here show that the construct is expressed only in MSNs and is restricted to the D1R-expressing cell population in the striatum. Thus the transgenic mouse line is a good tool for the study of mGluR5 selectively in D1R expressing neurons.