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This Article Full Text Full Text (PDF) All Versions of this Article: 98/6/3242    most recent 00677.2007v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Tashiro, A. Articles by Bereiter, D. A. Search for Related Content PubMed PubMed Citation Articles by Tashiro, A. Articles by Bereiter, D. A.

Differential Effects of Estradiol on Encoding Properties of TMJ Units in Laminae I and V at the Spinomedullary Junction in Female Rats

A. Tashiro¹, K. Okamoto¹, S. B. Milam^2, and D. A. Bereiter¹

¹Department of Diagnostic and Biological Sciences, University of Minnesota School of Dentistry, Minneapolis, Minnesota; and ²Department of Oral and Maxillofacial Surgery, University of Texas Health Science Center, San Antonio, Texas

Submitted 19 June 2007; accepted in final form 8 October 2007

To determine whether estrogen status modulated dorsal horn neural activity relevant to temporomandibular joint (TMJ) processing single units were recorded in superficial and deep laminae at the trigeminal subnucleus caudalis/upper cervical cord (Vc/C1–2) junction of ovariectomized (OvX) female rats under barbiturate anesthesia after 17β-estradiol (E2) treatment for 2 days. E2 dose-dependently enhanced the response to intra-TMJ stimulation by adenosine triphosphate (ATP) of neurons classified as nociceptive specific (NS), but not wide dynamic range (WDR), in superficial laminae. ATP caused similar responses among NS and WDR neurons from deep laminae in all groups. By contrast, the cutaneous receptive field areas of WDR, but not NS, units in superficial and deep laminae were enlarged in high E2-treated (HE2) compared with low E2-treated (LE2) females. Units from untreated or vehicle-treated male rats displayed responses similar to those of LE2 females. TMJ units in superficial laminae from females were more likely to receive convergent cutaneous input and respond to jaw movement than males, independent of E2 treatment. Western blot analysis revealed similar levels of P2X2 and P2X3 receptor protein in Vc/C1–2 or trigeminal ganglion samples in all groups. Immunohistochemistry revealed dense terminal labeling for P2X3 receptors in superficial laminae and moderate labeling in deep laminae at the Vc/C1–2 junction. These data indicated a significant linkage between estrogen status and the magnitude of articular input evoked by ATP from TMJ neurons in the superficial laminae at the Vc/C1–2 junction, whereas estrogenic modulation of TMJ neurons in deep laminae affected only the convergent input from overlying facial skin.

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