The majority of bladder sensory afferents to the rat lumbosacral spinal cord are both IB4- and CGRP-positive

• Published in: Brain research Vol. 1062; no. 1; pp. 86 - 91
• Main Authors: Hwang, Se Jin, Oh, Jung Min, Valtschanoff, Juli G.
• Format: Journal Article
• Language: English
• Published: London Elsevier B.V 16.11.2005; Amsterdam Elsevier; New York, NY
• Subjects: Animals; Biological and medical sciences; Bladder; Calcitonin Gene-Related Peptide - metabolism; CGRP; Dorsal root ganglion; Fundamental and applied biological sciences. Psychology; Ganglia, Spinal - cytology; Ganglia, Spinal - metabolism; IB4; Immunohistochemistry; Lectins - metabolism; Lumbosacral Region; Male; Neural Pathways - metabolism; Neurons, Afferent - cytology; Neurons, Afferent - metabolism; Neuropeptide; Rats; Rats, Sprague-Dawley; Sensory afferent; Spinal Cord - cytology; Spinal Cord - metabolism; Staining and Labeling - methods; Substance P - metabolism; Tissue Distribution; Urinary Bladder - innervation; Vertebrates: urinary system; Sensory systems; Bladder; Sensory afferent; IB4; Dorsal root ganglion; CGRP; Neuropeptide; Spinal cord; Rat; Innervation; Rodentia; Central nervous system; Calcitonin gene related peptide; Vertebrata; Mammalia; Urinary system; Urinary bladder; Animal; Spinal ganglion; Lumbosacral
• ISSN: 0006-8993; 1872-6240
• DOI: 10.1016/j.brainres.2005.09.026

The rat urinary bladder is innervated by neurons in dorsal root ganglia (DRG) that express the neuropeptides calcitonin gene-related peptide (CGRP) and substance P (SP), and a fraction of bladder afferents can bind the non-peptidergic marker isolectin B4 (IB4). We used histochemical binding and axonal tracing to identify the bladder afferents, and immunocytochemistry to determine the degree of colocalization of CGRP with IB4 in their cell bodies in DRG and in their central axons in the spinal cord. In the L6 DRG, about 60% of CGRP-positive neurons were also positive for IB4. In the spinal cord, IB4 and CGRP colocalized in fibers and terminals in the inner part of lamina II, the lateral collateral path, and the sacral parasympathetic nucleus (SPN). In SPN, the majority of IB4-positive fibers and terminals were also CGRP-positive. After injection of IB4 into the bladder wall, immunoreaction for IB4 was detected in SPN, but not in lamina II. These results suggest that most IB4-positive afferents from the bladder are also CGRP-positive, and that the distinction between peptidergic and non-peptidergic bladder afferents based on IB4 binding is of limited validity.