This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a colleague 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 Request Permissions Citing Articles Citing Articles via Web of Science (4) Citing Articles via Google Scholar Google Scholar Articles by Shin, S.-W. Articles by Tong, C. Search for Related Content PubMed PubMed Citation Articles by Shin, S.-W. Articles by Tong, C. Related Collections Pain Pharmacology

---

PAIN MEDICINE

The Monoamine Reuptake Inhibitor Milnacipran Does Not Affect Nociception to Acute Visceral Distension in Rats

Sang-Wook Shin, MD^*, James C. Eisenach, MD^*, Srinias G. Rao, MD PhD, and Chuanyao Tong, MD^*

*Department of Anesthesiology, Wake Forest University School of Medicine, Winston-Salem, North Carolina; and Cypress Bioscience Inc., San Diego, California

Address correspondence to Chuanyao Tong, MD, Department of Anesthesiology, Wake Forest University School of Medicine, Medical Center Blvd., Winston-Salem, NC 27157. Address e-mail to ctong{at}wfubmc.edu No reprints will be available from the authors.

The role of antidepressants in the treatment of visceral pain has not been extensively examined. Milnacipran, an antidepressant that inhibits monoamine reuptake, is widely used in the treatment of depression and fibromyalgia. In this study, we sought to determine the activity of milnacipran against acute visceral nociception. Female virgin rats were studied 7 days after bilateral ovariectomy. For uterine cervical distension (UCD), two metal rods were inserted into the cervical osses under general anesthesia for manual distension. Colorectal distension (CRD) was performed by insertion of a balloon catheter into the descending colon and rectum, followed by manual inflation. Two electrodes were inserted into the rectus abdominus muscle for recording UCD- or CRD-induced reflex contraction, which was quantified by electromyography (EMG). A dose response for milnacipran, administered intrathecally or IV, was obtained for UCD and CRD stimulation. Milnacipran failed to inhibit the UCD-induced EMG response, whether administered IV or intrathecally. Similarly, IV milnacipran, administered either acutely or chronically, failed to inhibit the CRD-induced EMG response. CRD and UCD are well established animal models for the study of acute visceral pain. Milnacipran, although it provides some unique advantages compared with other antidepressants, is unlikely to produce analgesia after acute administration in the setting of acute visceral pain.

IMPLICATIONS: Neither intrathecal nor IV milnacipran, a monoamine reuptake inhibitor, inhibits an acute visceral pain response induced by colorectal or uterine cervical distension.