Volume 24, Issue S1 p. 811.1-811.1
Physiology
Free Access

Effect of 17β-estradiol on temporomandibular joint nociception in intact and castrated male rats

Larry L Bellinger

Larry L Bellinger

Biomedical Sciences, The Texas A&M University Health Sciences Center, Dallas, TX

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Phillip R Kramer

Phillip R Kramer

Biomedical Sciences, The Texas A&M University Health Sciences Center, Dallas, TX

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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 17β-estradiol (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 diestrus-1, -2; estrus and metestrus and ~70 pg/ml E2 boost during proestrus. The TMJ CFA (15μg/30μl) 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 DE12657-01 (LLB) and DE07188 (PRK).