Visceral
hypersensitivity and an increased response to stress are two of the main symptoms of
irritable bowel syndrome. Thus efforts to develop animal models of
irritable bowel syndrome have centred on both of these parameters. The
anticonvulsant gabapentin, which is widely used as an
analgesic agent, also reduces anxiety. No data exists to our knowledge of the effects of
gabapentin in animal models of co-morbid exaggerated stress response and
visceral pain. Our aim was to assess the effect of
gabapentin on stress and visceral
hypersensitivity in two different animal models of
irritable bowel syndrome. The animal models employed were the genetically susceptible Wistar Kyoto rat and the neonatally stressed maternal separation model. These animals were subjected to the open field paradigm to assess stress-induced defecation rates and colorectal distension to assess the level of visceral sensitivity.
Gabapentin (30 mg/kg) prevented the stress-induced increase in faecal pellet output in the maternally separated rat, but not the Wistar Kyoto animals. On the other hand
gabapentin (30 mg/kg) reduced the number of
pain behaviours in response to colorectal distension in both models. These results show that whilst both models have similar responses to
gabapentin in terms of
visceral pain they differ in terms of their physiological response to stress. This indicates that the origin of anxiety and perhaps then visceral
hypersensitivity differs in these models. Overall, these data suggest that
gabapentin may be a useful treatment in disorders of co-morbid
pain and an overactive stress system such as
irritable bowel syndrome.