Vol. 62, Issue 4, 828-835, October 2002

DNA Microarray Analysis of Cannabinoid Signaling in Mouse Brain in Vivo

Sophie Parmentier-Batteur, Kunlin Jin, Lin Xie, Xiao Ou Mao, and David A. Greenberg

Buck Institute for Age Research, Novato, California

To identify novel genes involved in cannabinoid receptor-mediated signaling, we used cDNA microarrays to detect changes in mRNA expression in the forebrains of mice 12 h after they were given a single intraperitoneal dose of the naturally-occurring Cannabis sativa alkaloid ⁹-tetrahydrocannabinol (⁹-THC) or the synthetic cannabinoid receptor agonist (R)-(+)-2,3-dihydro-5-methyl-3-[(morpholinyl)methyl] pyrrolo[1,2,3-de]-1,4-benzoxazin-yl-1-naphtalenylmethanone mesylate [R(+)-WIN 55,212-2]. Of ~11,000 genes from a mouse brain cDNA library that were probed, 65 showed altered (increased or decreased at least 2-fold) expression after exposure to ⁹-THC, 41 after exposure to R(+)-WIN 55,212-2, and 20 genes after exposure to both drugs. Genes affected similarly by ⁹-THC and R(+)-WIN 55,212-2 were considered likely to reflect cannabinoid receptor activation, and expression of the protein products of two such genes not previously implicated in cannabinoid signalingmelanocyte-specific gene-related gene 1 (MRG1) and hexokinase 4 (glucokinase, GK)was measured by Western blotting and immunohistochemistry. Western blots showed ~2-fold increases in the levels of both proteins in mouse forebrain. Immunohistochemistry revealed preferential localization of MRG1 to cerebral blood vessels and of GK to hypothalamic neurons. These findings suggest that MRG1 and GK are cannabinoid-regulated genes and that they may be involved in the vascular and hypothalamic effects of cannabinoids, respectively.