An endocannabinoid system is present in the mouse olfactory epithelium but does not modulate olfaction. Neuroscience 2015 Aug 06;300:539-53
Date
06/04/2015Pubmed ID
26037800Pubmed Central ID
PMC4485596DOI
10.1016/j.neuroscience.2015.05.056Scopus ID
2-s2.0-84930959429 (requires institutional sign-in at Scopus site) 14 CitationsAbstract
Endocannabinoids modulate a diverse array of functions including progenitor cell proliferation in the central nervous system, and odorant detection and food intake in the mammalian central olfactory system and larval Xenopus laevis peripheral olfactory system. However, the presence and role of endocannabinoids in the peripheral olfactory epithelium have not been examined in mammals. We found the presence of cannabinoid type 1 (CB1) and cannabinoid type 2 (CB2) receptor protein and mRNA in the olfactory epithelium. Using either immunohistochemistry or calcium imaging we localized CB1 receptors on neurons, glia-like sustentacular cells, microvillous cells and progenitor-like basal cells. To examine the role of endocannabinoids, CB1- and CB2- receptor-deficient (CB1(-/-)/CB2(-/-)) mice were used. The endocannabinoid 2-arachidonylglycerol (2-AG) was present at high levels in both C57BL/6 wildtype and CB1(-/-)/CB2(-/-) mice. 2-AG synthetic and degradative enzymes are expressed in wildtype mice. A small but significant decrease in basal cell and olfactory sensory neuron numbers was observed in CB1(-/-)/CB2(-/-) mice compared to wildtype mice. The decrease in olfactory sensory neurons did not translate to impairment in olfactory-mediated behaviors assessed by the buried food test and habituation/dishabituation test. Collectively, these data indicate the presence of an endocannabinoid system in the mouse olfactory epithelium. However, unlike in tadpoles, endocannabinoids do not modulate olfaction. Further investigation on the role of endocannabinoids in progenitor cell function in the olfactory epithelium is warranted.
Author List
Hutch CR, Hillard CJ, Jia C, Hegg CCAuthor
Cecilia J. Hillard PhD Associate Dean, Center Director, Professor in the Pharmacology and Toxicology department at Medical College of WisconsinMESH terms used to index this publication - Major topics in bold
AnimalsArachidonic Acids
Endocannabinoids
Glycerides
Male
Mice
Mice, Inbred C57BL
Mice, Knockout
Olfactory Mucosa
Olfactory Receptor Neurons
RNA, Messenger
Receptor, Cannabinoid, CB1
Receptor, Cannabinoid, CB2
Smell
Tissue Culture Techniques