Effect of 17 beta-estradiol on temporomandibular joint nociception in intact and castrated male rats
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abstract
Meal duration (MD) is a biological marker of complete Freund's adjuvant (CFA) induced temporomandibular joint (TMJ) nociception in rats and mice. In female rats the proestrus rise in 17estradiol (E2) attenuates CFA induced TMJ nociception (Endocrin. 150:3680, 2009). We determined if a proestrus increase in E2 would also attenuate CFA TMJ nociception in intact and castrated (CAST) rats (~240g). A artificial E2 cycle had low E2 (~10 pg/ml via Alzet pumps) during diestrus1, 2; estrus and metestrus and ~70 pg/ml E2 boost during proestrus. The TMJ CFA (15g/30l) groups included: intact or CAST with or without E2 and their respective control groups receiving TMJ saline (SAL) The rats (n=8 per group) in the computerized feeders received three artificial E2 cycles and then were TMJ injected with SAL or CFA. Meal size was similar in all groups prior to and following TMJ injections. CFA increased MD (P<0.01) in all groups compared to SAL controls. MD was (P<0.01) longer in the CAST + no E2 + TMJ CFA compared to all other CFA injected groups. The data demonstrate the lack of gonadal steroids increase CFA induced nociception. Importantly, the data show that giving CAST male rats proestrus levels of E2 decreased (P<0.01) nociception when compared to the CAST + no E2 + CFA TMJ group. Proestrus levels of E2 can attenuate TMJ nociception in both female and male rats. NIDCR DE1265701 (LLB) and DE07188 (PRK).
