Background: The activity of neurogenic differentiation 1 (Neurod1) decreases after morphine administration, which leads toimpairments of the stability of dendritic spines in primary hippocampal neurons, adult neurogenesis in mouse hippocampi, anddrug-associated contextual memory. The current study examined whether Neurod1 could affect the development of opioid tolerance. Methods: Lentivirus encoding Neurod1, microRNA-190 (miR-190), or short hairpin RNA against Neurod1 was injected into mouse hippocampi separately or combined (more than eight mice for each treatment) to modulate NeuroD1 activity. The antinociceptive median effective dose values of morphine and fentanyl were determined with tail-flick assay and used to calculate development of tolerance. Contextual learning and memory were assayed using the Morris water maze. Results: Decrease in NeuroD1 activity increased the initial antinociceptive median effective dose values of both morphine and fentanyl, which was reversed by restoring NeuroD1 activity. In contrast, decrease in NeuroD1 activity inhibited development of tolerance in a time-dependent manner, paralleling its effects on the acquisition and extinction of contextual memory. In addition, only development of tolerance, but not antinociceptive median effective dose values, was modulated by the expression of miR-190 and Neurod1 driven by Nestin promoter. Conclusions: Neurod1 regulates the developments of opioid tolerance via a time-dependent pathway through contextual learning and a short-response pathway through antinociception.
Bibliographical noteFunding Information:
This work was supported by the National Natural Science Foundation of China Grant No. 31100773 , National Basic Research Program of China Grant No. 2010CB945402 , Guangzhou International Science and Technology Cooperation Projects from Bureau of Science and Information Technology of Guangzhou Municipal Government Grant No. 2012J5100007 , Guangdong Natural Science Foundation Grant No. S2012010010087 , and National Institutes of Health Grant No. DA031442-A1 .
© 2014 Society of Biological Psychiatry.
- Water maze