Sex differences in the activation of the spinoparabrachial circuit by visceral pain
| Autor: | Richard J. Traub, Shelby K. Suckow, Anne Z. Murphy, Malcolm E. Johns |
|---|---|
| Rok vydání: | 2009 |
| Předmět: |
Male
medicine.medical_specialty Stilbamidines Colon Central nervous system Receptors Opioid mu Pain Experimental and Cognitive Psychology Tritium Article Rats Sprague-Dawley Behavioral Neuroscience Internal medicine Neural Pathways medicine Animals Pain Measurement Brain Mapping Medulla Oblongata Sex Characteristics Morphine Visceral pain Enkephalin Ala(2)-MePhe(4)-Gly(5) Spinal cord Rats Analgesics Opioid medicine.anatomical_structure Endocrinology Spinal Cord Opioid Medulla oblongata Autoradiography Female Stress Mechanical μ-opioid receptor medicine.symptom Psychology Sex characteristics medicine.drug |
| Zdroj: | Physiology & Behavior. 97:205-212 |
| ISSN: | 0031-9384 |
| Popis: | Women are more sensitive to most noxious visceral stimuli, both in terms of intensity and frequency. The spinoparabrachial (spino-PBn) pathway is an essential neural circuit for the central relay of viscerosensitive information, but studies characterizing the anatomical and physiological characteristics of this pathway have only been conducted in males. Sex differences in the anatomical and/or physiological organization of the spino-PBn may contribute to the sexually dimorphic incidence rate for visceral pain syndromes. Retrograde labeling and colorectal distention (CRD) induced Fos expression was used to delineate the spino-PBn circuit in male and cycling female Sprague–Dawley rats. The ability of morphine to suppress CRD evoked responses was also examined. Neurons retrogradely labeled from the PBn were localized primarily within the superficial dorsal horn and sacral parasympathetic nucleus of the L5–S1 spinal cord. While no sex differences were noted in either the distribution of spino-PBn neurons or in CRD-induced Fos expression, significantly greater Fos expression was noted specifically in spino-PBn neurons in males compared to females. Morphine selectively attenuated Fos expression in spino-PBn neurons in males, but not females. Subsequent anatomical studies showed significantly reduced mu opioid receptor protein levels and radioligand binding within the PBn of females in comparison to males. Together, these data indicate that there are profound sex differences in how a noxious visceral stimulus and opiates engage the spino-PBn pathway, which may account for the observed clinical differences in visceral pain sensitivity and morphine antinociception. |
| Databáze: | OpenAIRE |
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