Mu Opioid Receptors in Gamma-Aminobutyric Acidergic Forebrain Neurons Moderate Motivation for Heroin and Palatable Food.

Background: Mu opioid receptors (MORs) are central to pain control, drug reward, and addictive behaviors, but underlying circuit mechanisms have been poorly explored by genetic approaches. Here we investigate the contribution of MORs expressed in gamma-aminobutyric acidergic forebrain neurons to major biological effects of opiates, and also challenge the canonical disinhibition model of opiate reward.

Methods: We used Dlx5/6-mediated recombination to create conditional Oprm1 mice in gamma-aminobutyric acidergic forebrain neurons.

A novel anxiogenic role for the delta opioid receptor expressed in GABAergic forebrain neurons.

Background: The delta opioid receptor (DOR) is broadly expressed throughout the nervous system; it regulates chronic pain, emotional responses, motivation, and memory. Neural circuits underlying DOR activities have been poorly explored by genetic approaches. We used conditional mouse mutagenesis to elucidate receptor function in GABAergic neurons of the forebrain.

Mouse strain differences in locomotor, sensitisation and rewarding effect of heroin; association with alterations in MOP-r activation and dopamine transporter binding.

There is growing agreement that genetic factors play an important role in the risk to develop heroin addiction, and comparisons of heroin addiction vulnerability in inbred strains of mice could provide useful information on the question of individual vulnerability to heroin addiction. This study examined the rewarding and locomotor-stimulating effects of heroin in male C57BL/6J and DBA/2J mice. Heroin induced locomotion and sensitisation in C57BL/6J but not in DBA/2J mice.