Endometriosis-induced vaginal hyperalgesia in the rat: Effect of estropause, ovariectomy, and estradiol replacement

Karen J Berkley, Stacy L McAllister, Briane E Accius, Kenneth P Winnard
Pain · 2007 · vol. 132(Supplement 1) , pp. S150–S159 · doi:10.1016/j.pain.2007.09.022 · PMID:17959309 · W1972354083
article OA: green CC0 ⤵ 45 in-corpus citations
🔓 Open OA copy View on OpenAlex View on PubMed View at publisher
⚙ AI-generated summary by claude@2026-06, 2026-06-08 ⓘ

This study found that endometriosis-induced vaginal hyperalgesia in rats is exacerbated by estradiol and that ovariectomy followed by estradiol replacement alleviates this type of hyperalgesia.

One-sentence paraphrase of the abstract; not a substitute for reading it. No clinical advice. How this works

Abstract

Endometriosis (ENDO) is a painful disorder defined by extrauteral endometrial growths. It is created in rats by autotransplanting pieces of uterus (which form cysts), or, for shamENDO, fat (no cysts). ENDO induces vaginal hyperalgesia, likely via central sensitization. The severity of this hyperalgesia correlates with estradiol levels during the estrous cycle, suggesting the hyperalgesia is estradiol-modulated. If so, then hyperalgesic severity should track estradiol changes during reproductive senescence (estropause) when estradiol levels initially decrease, then increase. Using psychophysical methods to assess vaginal nociception, we found that the severity of ENDO-induced hyperalgesia paralleled estradiol changes during estropause: hyperalgesia first decreased, then returned. Furthermore, the return occurred regardless of the presence of the cysts (excised in some rats). This finding provides further support for ENDO's likely centrally-mediated effects. Additionally, the results suggest that elimination of estradiol via ovariectomy (OVX) should alleviate ENDO-induced hyperalgesia and estradiol replacement should restore it. However, in healthy and shamENDO rats, OVX produces a vaginal hyperalgesia that is alleviated by estradiol, likely via estradiol's peripheral influences on the vagina. Hence, we tested the hypothesis that OVX in ENDO rats would trigger a different type of vaginal hyperalgesia dependent on the loss of estradiol. We predicted that the opposing influences of estradiol on ENDO- and OVX-induced hyperalgesia would cancel each other. As predicted, OVX had no effect on ENDO-induced hyperalgesia and estradiol replacement alleviated it. These results suggest that, in intact rats, ENDO-induced vaginal hyperalgesia is exacerbated by estradiol, and that different mechanisms underlie ENDO-induced versus OVX-induced vaginal hyperalgesia.

My notes (saved in your browser only)

Condition tags

mesh:D004715mesh:D017699endometriosis

MeSH descriptors

Endometriosis Estradiol Estrous Cycle Hyperalgesia Pelvic Pain Vagina Animals Endometriosis Endometriosis Endometriosis Estradiol Estradiol Estradiol Estrous Cycle Estrous Cycle Female Hormone Replacement Therapy Hyperalgesia Hyperalgesia Hyperalgesia

Citation neighborhood

Papers in the corpus that this work cites (lower rings, blue) and that cite this one (upper rings, green). Dot size scales with the paper's in-corpus citation count — bigger dot = more influential within the endo/adeno field. Click a dot to open that paper. [ expand to 2 hops ] — adds papers reached through this work's immediate citers/citees. Heavier; up to 60 extra dots.

References (34)

Cited by (45)

Source provenance

europepmc
last seen: 2026-06-04T01:30:01.192114+00:00
openalex
last seen: 2026-06-04T00:00:01.174412+00:00
pubmed
last seen: 2026-05-13T22:14:48.452140+00:00
License: CC0 · commercial use OK