Journal of neuroscience methods
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J. Neurosci. Methods · Jun 2003
A double-lumen intrathecal catheter for studies of modulation of spinal opiate tolerance.
Studies of spinal opioid tolerance frequently employ a spinal infusion model in which a single-lumen intrathecal (IT) catheter is connected to an osmotic mini pump. We have modified this model by developing a double-lumen catheter system that permits continuous delivery of the toleragen to the IT space and allows for examination of the effects of concurrent IT drug administration without interruption of the ongoing infusion. The catheter is constructed of two pieces of PE10 tubing fused to the lumens of a dual-lumen catheter (8 cm) with one PE10 tube used as an infusion line connected to an osmotic pump and the other for injection. ⋯ The profile of the tolerance development and the response to drug manipulation using the double-lumen catheter are similar to previous findings in the spinal infusion model which used a single-lumen catheter. Most importantly, we demonstrate that concurrent probe drug testing and/or concurrent drug treatment can be achieved without interruption of spinal infusion of morphine. Using the double-lumen catheter model expands the range of possibility for studies of spinal opiate tolerance and spinal drug delivery.
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J. Neurosci. Methods · Jun 2003
Quantitative assessment of directed hind limb scratching behavior as a rodent itch model.
Hind limb scratching is used increasingly as an itch model in rodents. Scratching is usually quantified as the number of scratching bouts over a 60 min period. Since the antipruritic effect of scratching should depend on the total time of skin contact, then the duration of scratching bouts and within-bout scratching frequency may also be important factors. ⋯ Within-bout scratching frequency remained constant over time at 8 Hz. The number of scratching bouts was suppressed in a dose dependent manner by naltrexone (3 and 5 mg/kg), while the individual bout duration and the within-bout frequency were not significantly different compared with serotonin-evoked scratching without naltrexone. These results validate the total number of scratching bouts as an indicator of the magnitude of itch-related scratching.