Expression of the CB1 and CB2 receptor messenger RNAs during embryonic development in the rat
Section snippets
Preparation of rat embryo tissue
Timed-pregnant Sprague–Dawley rats purchased from Taconic Farms (Germantown, NY, U.S.A.) were killed by CO2 inhalation. The uteri were dissected on ice. The day of the vaginal plug was designated as E1. Embryos plus uteri (E8–E13) or embryos alone (E13, E15, E17, E18, E19, E20 and E21) were frozen on dry ice and stored at −80°C until sectioning. Serial 12-μm-thick sections in sagittal and transversal planes were collected on silanized slides, briefly dried at 37°C and stored at −80°C until
Results
The following are the results obtained using the antisense probes. No signal was obtained when using the sense probes and are therefore not shown.
Discussion
Although exogenous cannabinoids have been associated with teratogenic effects, the role of endogenous cannabinoids remains largely unknown. In the present work, we have studied the fetal distribution of the two known cannabinoid receptor mRNAs, as well as the presence of these receptor mRNAs in the uterus and placenta. The expression of these receptor mRNAs during development suggests that exogenous as well as endogenous cannabinoids may affect fetal development. Recently, the presence of CB1
Conclusions
Our findings may provide some insight into the functional role of endogenous cannabinoids and into possible targets of exogenous cannabinoids during pregnancy.
In addition, our findings may also provide information for possible medicinal uses of CB1 versus CB2 agonists in a variety of known diseases where marijuana seems beneficial. Marijuana has been used for the treatment of ailments associated with cancer chemotherapy, glaucoma, AIDS, multiple sclerosis and other diseases (for a review see
Acknowledgements
We wish to thank Dr Stefen Lolait and Dr Tom Bonner for the the CB1 receptor plasmid templates, and Dr Sean Munro for the CB2 receptor plasmid template. We also thank Dr Ken Mackie for providing us with the rat CB1 antibody. Finally, we would like to thank Ricardo Dreyfuss for the photomicrography.
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