Acute bladder inflammation differentially affects rat spinal visceral nociceptive neurons

• Published in: Neuroscience letters Vol. 467; no. 2; pp. 150 - 154
• Main Authors: Ness, T.J., Castroman, P.J., Randich, A.
• Format: Journal Article
• Language: English
• Published: Shannon Elsevier Ireland Ltd 25.12.2009; Elsevier
• Subjects: Acute Disease; Anesthesia; Animals; Bacterial diseases; Bacterial diseases of the urinary system; Biological and medical sciences; Cystitis; Cystitis - chemically induced; Cystitis - physiopathology; Female; Fundamental and applied biological sciences. Psychology; Human bacterial diseases; Infectious diseases; Medical sciences; Nociceptors - physiology; Posterior Horn Cells - physiology; Rats; Rats, Sprague-Dawley; Somesthesis and somesthetic pathways (proprioception, exteroception, nociception); interoception; electrolocation. Sensory receptors; Spinal; Spine - physiopathology; Urinary bladder; Urinary Bladder - physiopathology; Vertebrates: nervous system and sense organs; Visceral; Zymosan; Zymosan; Spinal; Visceral; Urinary bladder; Cystitis; Nociception; Urinary system disease; Rat; Acute; Rodentia; Urinary tract disease; Vertebrata; Mammalia; Neuron; Urinary system; Animal; Bladder disease
• ISSN: 0304-3940; 1872-7972
• DOI: 10.1016/j.neulet.2009.10.027

The present investigation examined the effect of inflammation produced by intravesical zymosan on spinal dorsal horn neuronal responses to urinary bladder distension (UBD). Extracellular single-unit recordings of neurons excited by UBD were obtained in spinalized female Sprague–Dawley rats. Neurons were classified as Type I—inhibited by heterotopic noxious conditioning stimuli (HNCS) or as Type II—not inhibited by a HNCS. In Experiment 1—following neuronal characterization, 1% zymosan was infused into the bladder and after 2 h spinal units were recharacterized. Control rats received intravesical saline or subcutaneous zymosan. In Experiment 2—rats were pretreated with intravesical zymosan 24 h prior to surgical preparation. Control rats received anesthesia only. 137 spinal dorsal horn neurons excited by UBD were characterized. In comparison with controls, Type II neurons demonstrated increased spontaneous and UBD-evoked activity following intravesical zymosan treatment (both Experiments 1 and 2) whereas Type I neurons demonstrated either no change (Experiment 1) or decreased activity (Experiment 2) following bladder inflammation. No significant changes were noted in neuronal activity in control experiments. Inflammation differentially affects subpopulations of spinal dorsal horn neurons excited by UBD that can be differentiated according to the effect of HNCS. This results in an altered pattern of spinal sensory transmission that may serve as the mechanism for the generation of visceral nociception.