The Influence of an Adrenergic Antagonist Guanethidine on the Distribution Pattern and Chemical Coding of Caudal Mesenteric Ganglion Perikarya and Their Axons Supplying the Porcine Bladder

Abstract

This study was aimed at disclosing the influence of intravesically instilled guanethidine (GUA) on the distribution, relative frequency and chemical coding of both the urinary bladder intramural sympathetic nerve fibers and their parent cell bodies in the caudal mesenteric ganglion (CaMG) in juvenile female pigs. GUA instillation led to a profound decrease in the number of perivascular nerve terminals. Furthermore, the chemical profile of the perivascular innervation within the treated bladder also distinctly changed, as most of axons became somatostatin-immunoreactive (SOM-IR), while in the control animals they were found to be neuropeptide Y (NPY)-positive. Intravesical treatment with GUA led not only to a significant decrease in the number of bladder-projecting tyrosine hydroxylase (TH) CaMG somata (94.3 ± 1.8% vs. 73.3 ± 1.4%; control vs. GUA-treated pigs), but simultaneously resulted in the rearrangement of their co-transmitters repertoire, causing a distinct decrease in the number of TH⁺/NPY⁺ (89.6 ± 0.7% vs. 27.8 ± 0.9%) cell bodies and an increase in the number of SOM-(3.6 ± 0.4% vs. 68.7 ± 1.9%), calbindin-(CB; 2.06 ± 0.2% vs. 9.1 ± 1.2%) or galanin-containing (GAL; 1.6 ± 0.3% vs. 28.2 ± 1.3%) somata. The present study provides evidence that GUA significantly modifies the sympathetic innervation of the porcine urinary bladder wall, and thus may be considered a potential tool for studying the plasticity of this subdivision of the bladder innervation.

Keywords: guanethidine; inferior mesenteric ganglion; neuropeptides; noradrenergic nerve fibers; pig; urinary bladder.

Figure 1

The distribution and relative frequency of dopamine β-hydroxylase (DβH)—immunoreactive (IR) nerve fibers in control (contr.) and guanethidine (GUA)—treated pigs; in the control animals few DβH-IR nerve fibers were observed in the muscle layer (mL; a,b); a moderate number of noradrenergic nerve terminals was present in the submucosal layer (sL; d,e); a single DβH-containing nerve fibers were found beneath the urothelium (u; g,h) and a very dense meshwork of noradrenergic nerve fibers supplied the wall of blood vessels (bv; j,k); after GUA treatment only a few nerve terminals were observed in the wall of blood vessels (bv; l) while no DβH-IR nerve fibers were found in the muscle layer (mL; c), submucosal layer (sL; f,i,l) or beneath the urothelium (u; i); ×20.

Figure 2

The distribution of DβH—(green labelled fibers) and neuropeptide Y (NPY)—(a,d,i,l,m,p), somatostatin (SOM)—(b,e,n,r), vasoactive interstitial polypeptide (VIP)—(c,f), galanin (GAL)—(g,j), calbindin (CB)—(h,k) or neuronal nitric oxide synthase (nNOS)-positive (o,s; red labelled fibers) nerve fibers in the muscle layer (mL), submucosal layer (sL) and blood vessels (bv) of the urinary bladder wall in the control (a–c,g–i,m–o) and GUA-treated (d–f,j–l,p–s) pigs. Red and green channels were digitally superimposed. Double-labelled fibers are yellow to orange and most of them are indicated with arrows; ×20 (a–p); ×40 (r,s).

Figure 3

Representative images of caudal mesenteric ganglion-urinary bladder projecting neurons (CaMG-UBPN) in the control pigs. All the images were taken separately from blue (a,d,g,j,m,p), green (b,e,h,k,n,r) and red (c,f,i,l,o,s) fluorescent channels. Long arrows represent fast blue-positive (FB⁺) CaMG-UBPN (a,d,g,j,m), which were simultaneously tyrosine hydroxylase-positive (TH⁺; b,e,h,k,n) and NPY⁺ (c), SOM⁺ (f), CB⁺ (i), VIP⁺ (l) or GAL⁺ (o). Short arrows represent FB⁺ CaMG-UBPN (g,j,m,p), which were simultaneously TH⁺ (h,k,n,r) but CB-negative (CB⁻; i), VIP⁻ (l), GAL⁻ (o) or nNOS⁻ (s). Double arrows represent FB⁺ CaMG-UBPN (g,m,p), which were simultaneously both TH⁻ (h,n,r) and CB⁻ (i), GAL⁻ (o) or nNOS⁻ (s). Bar in images (a–c) and (g–s)—50 μm; Bar in images (d–f)—20 μm.

Figure 4

Representative images of CaMG-UBPN in the GUA-treated pigs. All the images were taken separately from blue (a,d,g,j,m,p), green (b,e,h,k,n,r) and red (c,f,i,l,o,s) fluorescent channels. Long arrows represent FB⁺ CaMG-UBPN (g,j,m,p), which were simultaneously TH⁺ (h,k,n,r) and SOM⁺ (i), GAL⁺ (l), CB⁺ (o) or nNOS⁺ (s). Short arrows represent FB⁺ CaMG-UBPN (a,d,g), which were simultaneously TH⁺ (b,e,h) but NPY⁻ (c), VIP⁻ (f) or SOM⁻ (i). Double arrows represent FB⁺ CaMG-UBPN (m), which were simultaneously both TH⁻ (n) and CB⁻ (o). Bar in images (a–c) and (g–s)—50 μm; Bar in images (d–f)—20 μm.