In vivo characterization of colorectal and cutaneous inputs to lumbosacral dorsal horn neurons in the XXXX spinal cord.

@entity32 @entity19 @entity29 @entity158 @entity490 @entity14 @entity5161
UNASSIGNED: Chronic @entity490 is a common symptom of @entity29 and often persists in the absence of gut @entity32 . Although the mechanisms responsible for ongoing @entity158 are unknown, clinical and preclinical evidence suggests lumbosacral spinal cord dorsal horn neurons contribute to these symptoms. At present, we know little about the intrinsic and synaptic properties of this population of neurons in either normal or inflammed conditions. Therefore, we developed an in vivo preparation to make patch-clamp recordings from superficial dorsal horn (SDH) neurons receiving colonic inputs in na  ve male @entity19 . Recordings were made in the lumbosacral spinal cord (L6-S1) under @entity5161 anesthesia. Noxious @entity14 ( @entity14 ) was used to determine whether SDH neurons received inputs from mechanical stimulation/distension of the colon. Responses to hind paw/tail cutaneous stimulation and intrinsic and synaptic properties were also assessed, as well as action potential discharge properties. Approximately 11% of lumbosacral SDH neurons in the cohort of neurons sampled responded to @entity14 and a majority of these responses were subthreshold. Most @entity14 (80%) also responded to cutaneous stimuli, compared with <50% of @entity14 -non-responsive neurons. Furthermore, @entity14 had more hyperpolarized resting membrane potentials, larger rheobase currents, and reduced levels of excitatory drive, compared to @entity14 -non-responsive neurons. Our results demonstrate that @entity14 can be distinguished from @entity14 -non-responsive neurons by several differences in their membrane properties and excitatory synaptic inputs. We also demonstrate that SDH neurons with colonic inputs show predominately subthreshold responses to @entity14 and exhibit a high degree of viscerosomatic convergence.
