Role Of ICC In Mediation Of Sympathetic Neurotransmission And Modulation Of Smooth Muscle Tone In Prostate

Part IMorphological study of interstitial cells of Cajal mediating sympathetic neurotransmission in guinea pig prostate Experiment1:Ultrastructure contact between prostate ICC with nerve and smooth muscleObjective:To observe the ultrastructural characteristics of prostate ICC in guinea pig and the ultrastructural relationship between ICC and nerves, smooth muscle cells.Method:The guinea pig prostate slices were made, and ultrastructural features and the relationship between ICC and nerves or smooth muscle cells were observed by transmission electron microscopy experiments.Results:Ultrastructurally, many special interstitial cells have been found in the present study in accordance with the majority ultrastructural criterions of ICC in gut. Under electron microscope, prostate ICC were distributed between smooth muscle bundles; within border between smooth muscle and glandular layer. Prostate ICC were closely related with nerve fibers by synaptic-like junctions. One ICC can connect with two or more nerve terminals close neighboring them. ICCs were also closely related with smooth muscle cells by gap junctions and close appositions.Conclusion:Prostate ICC in guinea pig possesses ultrastructural features required to mediate nerve signals and regulate the tone of smooth muscle. Part IMorphological study of interstitial cells of Cajal mediating Sympathetic neurotransmission in guinea pig prostate Experiment2:Morphology contact between ICC with sympathetic nerve and smooth muscle in prostateObjective:To observe the morphological relationships between sympathetic nerves, ICC and smooth muscle cells in the guinea pig prostate.Method:The guinea pig prostate slices were made for double-labeling immunohistochemistry. Anti-c-Kit was used to identify ICC, anti-TH and anti-DβH were used to identify sympathetic nerve fibers, anti-a-actin was used to identify smooth muscle cells. Double-labeling was performed for c-Kit and TH, c-Kit and DβH, c-Kit and a-actin.Results:A network of spindle-or stellate-shaped, c-Kit-positive ICC and a network of TH-immunoreactive and DβH-immunoreactive sympathetic nerve bundles ran together among the smooth muscle bundles and in the stroma between the smooth muscle layer and the glandular tissue. ICC surrounded or were arranged in parallel to sympathetic nerve bundles. Many close points of contact were evident between sympathetic nerve fibers and ICC. ICCs were always closely apposed to the smooth muscle cells and ran in parallel to the long axis of the smooth muscle bundles. Surprisingly, prostate ICC co-expressed TH and DPH, two markers of sympathetic nerve fibers.Conclusion:ICC in the guinea pig prostate possess the morphological characteristics required to mediate sympathetic signals and regulate the tone of smooth muscle. ICC themselves have the potential to produce NE to augment the sympathetic neuron signals. Part IIFunctional study of interstitial cells of Cajal mediating sympathetic neurotransmission in guinea pig prostateExperiment1:Expression of Cx43and al receptor in prostate ICCObjective:To observe al-adrenoceptor and Cx43expressed in prostate ICC of guinea pig.Method:The guinea pig prostate slices were made and ICCs were isolated and cultured for double-labeling immunohistochemistry. Double-labeling was performed for c-Kit and al-adrenoceptor, c-Kit and Cx43.Results:Double-labeled sections revealed a high level of al-adrenoceptor and Cx43colocalization with c-Kit between smooth muscle bundles in the guinea pig prostate. Moreover, al-adrenoceptor immunoreactivity was stronger in ICCs than in smooth muscle cells. Double-labeled cells also revealed a high level of al-adrenoceptor and Cx43colocalization with c-Kit in ICC.Conclusion:Prostate ICCs are target cells of the sympathetic nerve endings, and may transfer sympathetic nerve signals to smooth muscle cells with Cx43. Keywords: Part IIFunctional study of interstitial cells of Cajal mediating sympathetic neurotransmission in guinea pig prostateExperiment2:Effect of sympathetic neurotransmitter on the excitability of prostate ICCObjective:To observe the response of prostate ICC to sympathetic neurotransmitter NE.Method:ICCs currents were recorded by using the whole-cell patch-clamp technique with the perforated-patch configuration. The effect of NE was quantified by examining the peak amplitude of the inward currents. The involvement of a-adrenoceptor and al-adrenoceptor in this response was assessed by examining the effects of phentolamine and prazosin on the reaction to NE.Results:Prostate ICC were maintained at a holding potential of-60mV in the whole-cell patch-clamp mode. No spontaneous inward currents were recorded (n=6). Application of NE evoked a large single inward current in all ICC (n=6). In the presence of1μmol NE, the inward current was-106±29pA; in the presence of10μmol NE, the response was-210±68pA; and in the presence of100μmol NE, the response was-368±113pA. The amplitude of the NE-evoked current increased in a dose-dependent manner (P<0.01). After application of non-specific a-adrenoceptor antagonist(phentolamine) and al-adrenoceptors antagonist (prazosin), NE failed to evoke an inward current in all ICC tested.Conclusion:Prostate ICC are target cells of the sympathetic nerve endings, possessing the functional basis required to mediate sympathetic signals. Part IIFunctional study of interstitial cells of Cajal mediating sympathetic neurotransmission in guinea pig prostateExperiment3:Role of prostate ICC in NE-induced smooth muscle activityObjective:To investigate the role of prostate ICC in NE-induced smooth muscle activity.Method:Guinea pig prostate strips were mounted in a superfused organ-bath apparatus and the amplitude and frrequency of NE-evoked smooth muscle contraction were recorded before and after the presence of Glivec.Results:Contractions were recorded on isolated smooth muscle strips of guinea pig prostate under NE (50μmol/L).The frequency and amplitude of contraction were2.54±0.28/min and0.98±0.16g respectively. The amplitude of NE-evoked contraction was significantly inhibited in the presence of50μmol/L and200μmol/L Glivec (P<0.01), while the frequency was not affected (P>0.05).Conclusion:ICC are involved in the mediating of prostate sympathetic signals and regulation of smooth muscle activity.