Can Hybrid Synapse be Formed between Rat Spinal Motor Neurons and Major Pelvic Ganglion Neurons in vitro?

The purpose of this study is to determine whether synapses can be formed between spinal motor neurons (SMNs) and major pelvic ganglion (MPG) neurons of a rat in vitro. The green fluorescent protein (GFP)-labelled MPG cells were cultured together with SMNs in a specific medium. The synaptic-like contacts established between SMNs and MPG neurons were studied in co-cultures using morphologic and immunocytochemistry approaches. Phase-contrast observation of co-cultures showed apparent SMNs-MPG neurons contacts as early as three or four days in vitro. We demonstrate some evidence of synaptic contacts between SMNs and MPG neurons in vitro by immunostaining with antibody directed against postsynaptic density protein 95 (PSD-95). We describe the development process of a defined SMNs-MPG neurons co-culture system. The results suggest that the hybrid synapse formation that may occur between SMNs and MPG neurons in vitro played an essential role in the mechanisms of a regenerated bladder with an artificial somatic-autonomic reflex arc.

Changes in the Neurochemical Coding of the Anterior Pelvic Ganglion Neurons Supplying the Male Pig Urinary Bladder Trigone after One-Sided Axotomy of Their Nerve Fibers

The present study investigated the effect of unilateral axotomy of urinary bladder trigone (UBT)-projecting nerve fibers from the right anterior pelvic ganglion (APG) on changes in the chemical coding of their neuronal bodies. The study was performed using male pigs with immunohistochemistry and quantitative real-time PCR (qPCR). The animals were divided into a control (C), a morphological (MG) or a molecular biology group (MBG). APG neurons supplying UBT were revealed using the retrograde tracing technique with Fast Blue (FB). Unilateral axotomy resulted in an over 50% decrease in the number of FB+ neurons in both APG ganglia. Immunohistochemistry revealed significant changes in the chemical coding of FB+ cells only in the right ganglion: decreased expression of dopamine-B-hydroxylase (DBH)/tyrosine hydroxylase (TH) and up-regulation of the vesicular acetylcholine transporter (VAChT)/choline acetyltransferase (ChAT), galanin (GAL), vasoactive intestinal polypeptide (VIP) and brain nitric oxide synthase (bNOS). The qPCR results partly corresponded with immunofluorescence findings. In the APGs, genes for VAChT and ChAT, TH and DBH, VIP, and NOS were distinctly down-regulated, while the expression of GAL was up-regulated. Such data may be the basis for further studies concerning the plasticity of these ganglia under experimental or pathological conditions.

Changes in excitability and ion channel expression in neurons of the major pelvic ganglion in female type II diabetic mice

ABSTRACTBladder cystopathy is a common urological complication of diabetes, and has been associated with changes in parasympathetic ganglionic transmission and some measures of neuronal excitability in male mice. To determine whether type II diabetes also impacts excitability of parasympathetic ganglionic neurons in females, we investigated neuronal excitability and firing properties, as well as underlying ion channel expression, in major pelvic ganglion (MPG) neurons in control, 10-week, and 21-week db/db mice. Type II diabetes in Leprdb/db animals caused a non-linear change in excitability and firing properties of MPG neurons. At 10 weeks, cells exhibited increased excitability as demonstrated by an increased likelihood of firing multiple spikes upon depolarization, decreased rebound spike latency, and overall narrower action potential half-widths as a result of increased depolarization and repolarization slopes. Conversely, at 21 weeks MPG neurons of db/db mice reversed these changes, with spiking patterns and action-potential properties largely returning to control levels. These changes are associated with numerous time-specific changes in calcium, sodium, and potassium channel subunit mRNA levels. However, Principal Components Analysis of channel expression patterns revealed that the rectification of excitability is not simply a return to control levels, but rather a distinct ion channel expression profile in 21-week db/db neurons. These data indicate that type II diabetes can impact the excitability of post-ganglionic, parasympathetic bladder-innervating neurons of female mice, and suggest that the non-linear progression of these properties with diabetes may be the result of compensatory changes in channel expression that act to rectify disrupted firing patterns of db/db MPG neurons.