Neuroscience 2004 Abstract
| Presentation Number: | 286.8 |
|---|---|
| Abstract Title: | Effect of neonatal maternal separation stress (NMSS) on pain threshold and neurochemical responses of colonic mucosa and spinal cord to nociceptive colonic balloon distension in adult rats. |
| Authors: |
Lao, L.*1
1Ctr. for Integrative Med., Univ Maryland Sch Med, Baltimore, MD |
| Primary Theme and Topics |
Sensory Systems - Pain -- Spinal cord processing: anatomy and physiology |
| Secondary Theme and Topics | Neurological and Psychiatric Conditions<br />- Psychiatric Disorders<br />-- Other |
| Session: |
286. Visceral Nociception Poster |
| Presentation Time: | Sunday, October 24, 2004 4:00 PM-5:00 PM |
| Location: | San Diego Convention Center - Hall A-H, Board # K23 |
| Keywords: | MATERNAL SEPARATION STRESS , PAIN THRESHOLD , NEUROCHEMICAL RESPONSES , COLONIC MUCOSA |
Eric Ziea1, Justin Wu1, Lixing Lao2, Tianhua Ren1, David Yew3, Joseph Sung1.
Dept Med1, Anat3, Chin Univ Hong Kong.
Center Integrat Med2, Univ Maryland,Baltimore.
Childhood stress has been implicated as a contributing factor in irritable bowel syndrome(IBS).It has also been reported that neonatal maternal separation stress(NMSS) induces visceral hyperalgesia in rats, thus we used a colonic balloon distension(CBD) rat model to study the effect of NMSS on brain-gut axis neurochemical responses to nociceptive stimuli. Male neonatal SD rats were randomly divided into: 1.Maternal separation(MS;n=8) 3 hours/day on postnatal days 2-21 and 2.Non-handled control (n=8).CBD was performed on day 60 to assess abdominal withdrawal reflex (AWR),a marker of visceral pain. Pain threshold was defined as balloon pressure provoking a nociceptive AWR response to graded CBD. Substance P and serotonin (5-HT) expression along the brain-gut axis was evaluated by immunohistochemistry and ELISA.Pain threshold was significantly lower in the MS group than in control (P=0.023).AWR score was significantly higher in the MS group. Before CBD there were no significant differences in distal colon 5-HT cell number or content between groups (P=0.97;P=0.13);after CBD these increased significantly in the MS group compared to control (P=0.017;P=0.001).Spinal cord 5-HT content was significantly higher in the MS group before and after CBD.After CBD the MS group showed more activated serotonergic neurons in mid-brain dorsal raphe nuclei than control(P=0.02).There was no significant difference in substance P expression between groups.NMSS exacerbated 5-HT response in the visceral nociceptive pathway and adult visceral hyperalgesia,supporting the claim that childhood adversity induces 5-HT system abnormalities that may contribute to the development of IBS in adulthood.
Dept Med1, Anat3, Chin Univ Hong Kong.
Center Integrat Med2, Univ Maryland,Baltimore.
Childhood stress has been implicated as a contributing factor in irritable bowel syndrome(IBS).It has also been reported that neonatal maternal separation stress(NMSS) induces visceral hyperalgesia in rats, thus we used a colonic balloon distension(CBD) rat model to study the effect of NMSS on brain-gut axis neurochemical responses to nociceptive stimuli. Male neonatal SD rats were randomly divided into: 1.Maternal separation(MS;n=8) 3 hours/day on postnatal days 2-21 and 2.Non-handled control (n=8).CBD was performed on day 60 to assess abdominal withdrawal reflex (AWR),a marker of visceral pain. Pain threshold was defined as balloon pressure provoking a nociceptive AWR response to graded CBD. Substance P and serotonin (5-HT) expression along the brain-gut axis was evaluated by immunohistochemistry and ELISA.Pain threshold was significantly lower in the MS group than in control (P=0.023).AWR score was significantly higher in the MS group. Before CBD there were no significant differences in distal colon 5-HT cell number or content between groups (P=0.97;P=0.13);after CBD these increased significantly in the MS group compared to control (P=0.017;P=0.001).Spinal cord 5-HT content was significantly higher in the MS group before and after CBD.After CBD the MS group showed more activated serotonergic neurons in mid-brain dorsal raphe nuclei than control(P=0.02).There was no significant difference in substance P expression between groups.NMSS exacerbated 5-HT response in the visceral nociceptive pathway and adult visceral hyperalgesia,supporting the claim that childhood adversity induces 5-HT system abnormalities that may contribute to the development of IBS in adulthood.
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2004 Neuroscience Meeting Planner. San Diego, CA: Society for Neuroscience, 2004. Online.
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