Kramer P R, Bellinger L L
Department of Biomedical Sciences, Texas A&M Health Science Center, Baylor College of Dentistry, Dallas, Texas 75246, USA.
Endocrinology. 2009 Aug;150(8):3680-9. doi: 10.1210/en.2008-1707. Epub 2009 Apr 9.
A greater incidence of temporomandibular joint (TMJ) pain is reported in females, suggesting that gonadal hormones may play a role in this condition. However, the exact roles of 17beta-estradiol (E2) and progesterone (P4) in TMJ pain are not completely known. Two experiments were performed to determine the separate roles of E2 and P4 in TMJ nociception at various stages of the estrous cycle. Ovariectomized (OVX) rats were cycled with physiological concentrations of E2 or P4. The E2-cycled rats then received bilateral TMJ injections of saline (SAL) or complete Freund's adjuvant (CFA) on the morning of diestrus-2 (low E2 condition) or proestrus (high E2 condition). As a control, OVX rats (no ovarian E2 and no replacement) were injected with SAL or CFA. The TMJ nociception was measured using a validated novel method in which an increase in meal duration directly correlated to the intensity of deep TMJ nociception. In the E2 experiment, CFA injection, but not SAL, increased TMJ nociception in the OVX group, but the effect was less pronounced in diestrus-2 and even less in proestrus. In the P4 experiment, the rats receiving TMJ CFA in diestrus-2 (end of minor P4 surge) did not show an increase in TMJ nociception, whereas the rats injected in proestrus (major P4 surge), estrus (low P4), and metestrus (low P4) had similar increases in TMJ nociception. The hormones' concentration did not affect TMJ IL-1beta, IL-6, C-C motif ligand 20, or C-X-C motif ligand 2 or the trigeminal ganglia calcitonin gene-related peptide. The high physiological concentrations of E2 observed at proestrus and the low P4 concentrations observed at diestrus-2 attenuated or eliminated CFA-induced TMJ nociception. The results suggest that the cyclic estrous cycle concentrations of E2 and P4 can influence CFA-induced TMJ nociception in the rat.
据报道，颞下颌关节（TMJ）疼痛在女性中的发病率更高，这表明性腺激素可能在这种情况中起作用。然而，17β-雌二醇（E2）和孕酮（P4）在TMJ疼痛中的确切作用尚不完全清楚。进行了两项实验，以确定E2和P4在发情周期不同阶段对TMJ伤害感受的单独作用。对卵巢切除（OVX）的大鼠给予生理浓度的E2或P4进行周期处理。然后，在动情后期-2（低E2状态）或发情前期（高E2状态）的早晨，给经E2周期处理的大鼠双侧TMJ注射生理盐水（SAL）或完全弗氏佐剂（CFA）。作为对照，给OVX大鼠（无卵巢E2且未进行替代）注射SAL或CFA。使用一种经过验证的新方法测量TMJ伤害感受，即进食持续时间的增加与深部TMJ伤害感受的强度直接相关。在E2实验中，CFA注射而非SAL注射增加了OVX组的TMJ伤害感受，但在动情后期-2的作用不太明显，在发情前期甚至更小。在P4实验中，在动情后期-2（小P4激增结束时）接受TMJ CFA注射的大鼠未表现出TMJ伤害感受增加，而在发情前期（大P4激增）、发情期（低P4）和间情期（低P4）注射的大鼠TMJ伤害感受有类似增加。激素浓度未影响TMJ白细胞介素-1β、白细胞介素-6、C-C基序配体20或C-X-C基序配体2，也未影响三叉神经节降钙素基因相关肽。在发情前期观察到的高生理浓度E2和在动情后期-2观察到的低P4浓度减弱或消除了CFA诱导的TMJ伤害感受。结果表明，E2和P4的周期性发情周期浓度可影响大鼠中CFA诱导的TMJ伤害感受。
