IADR Abstract Archives
Testosterone and Nociceptive Response in Varicella-Zoster Virus Infection of Rats
Objectives: Post Herpetic Neuralgia (PHN) after herpes zoster (HZ) or Shingles is a common complaint. PHN is a chronic pain usually occurring few months after the episode of HZ. Testosterone can affect pain responses but the role of testosterone in PHNs remains unclear. Testosterone is converted into estrogen in certain areas including thalamus of the brain by enzyme aromatase to modulate pain. We tested our hypothesis that testosterone conversion to estrogen in thalamus attenuates PHN response.
Methods: Male Sprague-Dawley rats (300 gram) were divided (n=28/group) into virus and control group that received MeWo cells containing varicella Zoster Virus (VZV) the virus responsible for HZ or MeWo cells lacking virus, respectively. Guide cannulas were placed in the thalamic area for a portion of the rats using stereotaxic coordinates for local administration of drug. Virus injections (100 µl) were in the left whisker pad and contained either 60,000 pfu of virus or control. Both the groups were further divided in two drug groups receiving the aromatase inhibitor letrozole or the vehicle dimethyl sulfoxide. Drug was given either locally or systemically. The conversion of testosterone into estrogen is selectively inhibited using letrozole. The motivational and affective aspect of nociception was measured using Place Escape Avoidance Paradigm (PEAP) assay. Measurements were completed once a week for three weeks.
Results: Data obtained were statistically analyzed and demonstrated that virus injection significantly increased the pain response compared to the control. This pain response was significantly increased after administration of letrozole.
Conclusions: In conclusion, testosterone reduces the VZV associated pain response, in part, due to conversion into estrogen in the thalamic region.
Methods: Male Sprague-Dawley rats (300 gram) were divided (n=28/group) into virus and control group that received MeWo cells containing varicella Zoster Virus (VZV) the virus responsible for HZ or MeWo cells lacking virus, respectively. Guide cannulas were placed in the thalamic area for a portion of the rats using stereotaxic coordinates for local administration of drug. Virus injections (100 µl) were in the left whisker pad and contained either 60,000 pfu of virus or control. Both the groups were further divided in two drug groups receiving the aromatase inhibitor letrozole or the vehicle dimethyl sulfoxide. Drug was given either locally or systemically. The conversion of testosterone into estrogen is selectively inhibited using letrozole. The motivational and affective aspect of nociception was measured using Place Escape Avoidance Paradigm (PEAP) assay. Measurements were completed once a week for three weeks.
Results: Data obtained were statistically analyzed and demonstrated that virus injection significantly increased the pain response compared to the control. This pain response was significantly increased after administration of letrozole.
Conclusions: In conclusion, testosterone reduces the VZV associated pain response, in part, due to conversion into estrogen in the thalamic region.