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Alterations in afferent pathways from the urinary bladder of the rat in response to partial urethral obstruction
Author(s) -
Steers William D.,
Ciambotti Jonathan,
Etzel Barbara,
Erdman Susan,
de Groat William C.
Publication year - 1991
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.903100309
Subject(s) - urinary bladder , spinal cord , anatomy , urination , biology , ganglion , afferent , dorsal root ganglion , urinary system , lumbosacral joint , endocrinology , medicine , dorsum , neuroscience
Afferent pathways from the urinary bladder were examined with axonal tracing techniques in normal female Wistar rats and in those with partial urethral ligation. Following injection of wheat germ agglutinin‐horseradish peroxidase (HRP) into the bladder wall, HRP was detected in lumbosacral dorsal root ganglion cells and in afferent projections to the L 6 –S 1 spinal cord at sites in laminae I, II, V–VII, and X known to receive visceral afferent input. Partial urethral ligation (6 weeks) produced a sixfold increase in bladder weight and altered the morphology of bladder afferent pathways. Changes included an increase in the average cross‐sectional area of labelled neuronal profiles in L6 and ST dorsal root ganglia in obstructed (766 ± 378 μm 2 , P < 0.001) compared to control rats (528 ± 189 μm 2 ). The cross‐sectional area of the largest profiles also increased by approximately 40%. The mean number of labelled dorsal root ganglion cell profiles was similar in ligated (837 ± 198) and control (883 ± 352) groups. When compared to control animals the obstructed animals exhibited a 60% increase in the area of the labelled afferent terminal field in the intermediolateral region of the L 6 ‐S 1 spinal cord. This increased labelling was even more remarkable given that the volume of tracer per bladder weight injected into the hypertrophied bladder was 87% less than controls. These results provide evidence that bladder afferents project to regions of the spinal cord known to regulate micturition and that these afferents can undergo morphological alterations and/or changes in axoplasmic transport in response to urethral ligation. Changes may occur in response to increased target organ mass, increased neural activity, or alterations in the levels or activity of neurotrophic factors.