Environmental stressors transiently activate neural systems that inhibit pain responsiveness. This phenomenon, called stress-induced analgesia (SIA), engages both opioid and nonopioid mechanisms. We have recently reported that nonopioid SIA may be mediated by the mobilization of endogenous cannabinoid compounds, such as 2-arachidonoylglycerol (2-AG), in the midbrain periaqueductal gray (PAG) [Hohmann et al., Nature 435: 1108-1112, 2005]. Our results show, indeed, that nonopioid SIA is abolished by cannabinoid receptor antagonists, is associated with 2-AG accumulation in the PAG, and is enhanced by pharmacological agents that block 2-AG deactivation. However, the mechanisms governing 2-AG signaling in the PAG during SIA remain largely unknown. Our central hypothesis is that stress stimuli that result in nonopioid SIA activate phospholipase C (PLC) and diacylglycerol lipase (DGL) in select neurons of the PAG, causing the rapid mobilization of 2-AG. Newly released 2-AG engages local cannabinoid receptors to induce nonopioid SIA, and is subsequently deactivated through monoacylglycerol lipase (MGL)-mediated hydrolysis. Glutamatergic stimulation of group I metabotropic receptors (mGluR), which are positively coupled to PLC/DGL, may be responsible for initiating these events. We will test this hypothesis with a series of experiments, which are expected to demonstrate that: 1) foot shock stress elicits on-demand mobilization of 2-AG in the PAG by activating PLC/DGL; 2) selective inhibition of MGL activity in the PAG increases 2-AG accumulation in this structure and amplifies SIA; 3) group I mGluR activation in the PAG stimulates 2-AG mobilization through PLC/DGL to induce SIA; and 4) key components of the 2-AG signaling system (i.e. mGluRS, PLC, DGL, cannabinoid receptors, MGL) are expressed in select neurons of the PAG. The results of these studies will elucidate, for the first time, biochemical and physiological mechanisms governing 2-AG signaling in the brain and determine the role of this endocannabinoid mediator in pain modulation. Furthermore, the results will provide essential information on the mechanisms responsible for endocannabinoid deactivation in the brain, which may facilitate the development of novel analgesic and anti- stress medicines. ? ? ? ?

Agency
National Institute of Health (NIH)
Institute
National Institute on Drug Abuse (NIDA)
Type
Research Project (R01)
Project #
5R01DA021644-02
Application #
7275956
Study Section
Somatosensory and Chemosensory Systems Study Section (SCS)
Program Officer
Purohit, Vishnudutt
Project Start
2006-08-15
Project End
2011-05-31
Budget Start
2007-06-01
Budget End
2008-05-31
Support Year
2
Fiscal Year
2007
Total Cost
$428,315
Indirect Cost
Name
University of Georgia
Department
Psychology
Type
Schools of Arts and Sciences
DUNS #
004315578
City
Athens
State
GA
Country
United States
Zip Code
30602
Carey, Lawrence M; Gutierrez, Tannia; Deng, Liting et al. (2017) Inflammatory and Neuropathic Nociception is Preserved in GPR55 Knockout Mice. Sci Rep 7:944
Carey, Lawrence M; Slivicki, Richard A; Leishman, Emma et al. (2016) A pro-nociceptive phenotype unmasked in mice lacking fatty-acid amide hydrolase. Mol Pain 12:
Deng, Liting; Guindon, Josée; Cornett, Benjamin L et al. (2015) Chronic cannabinoid receptor 2 activation reverses paclitaxel neuropathy without tolerance or cannabinoid receptor 1-dependent withdrawal. Biol Psychiatry 77:475-87
Marcus, David J; Zee, Michael; Hughes, Alex et al. (2015) Tolerance to the antinociceptive effects of chronic morphine requires c-Jun N-terminal kinase. Mol Pain 11:34
Guindon, Josée; Deng, Liting; Fan, Baochang et al. (2014) Optimization of a cisplatin model of chemotherapy-induced peripheral neuropathy in mice: use of vitamin C and sodium bicarbonate pretreatments to reduce nephrotoxicity and improve animal health status. Mol Pain 10:56
Rahn, Elizabeth J; Deng, Liting; Thakur, Ganesh A et al. (2014) Prophylactic cannabinoid administration blocks the development of paclitaxel-induced neuropathic nociception during analgesic treatment and following cessation of drug delivery. Mol Pain 10:27
Guindon, Josée; Lai, Yvonne; Takacs, Sara M et al. (2013) Alterations in endocannabinoid tone following chemotherapy-induced peripheral neuropathy: effects of endocannabinoid deactivation inhibitors targeting fatty-acid amide hydrolase and monoacylglycerol lipase in comparison to reference analgesics following c Pharmacol Res 67:94-109
Guindon, Josée; Hohmann, Andrea G (2013) Use of sodium bicarbonate to promote weight gain, maintain body temperature, normalize renal functions and minimize mortality in rodents receiving the chemotherapeutic agent cisplatin. Neurosci Lett 544:41-6
Deng, Liting; Guindon, Josee; Vemuri, V Kiran et al. (2012) The maintenance of cisplatin- and paclitaxel-induced mechanical and cold allodynia is suppressed by cannabinoid CBýýý receptor activation and independent of CXCR4 signaling in models of chemotherapy-induced peripheral neuropathy. Mol Pain 8:71
Gregg, Laura C; Jung, Kwang-Mook; Spradley, Jessica M et al. (2012) Activation of type 5 metabotropic glutamate receptors and diacylglycerol lipase-? initiates 2-arachidonoylglycerol formation and endocannabinoid-mediated analgesia. J Neurosci 32:9457-68

Showing the most recent 10 out of 32 publications