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Synaptic connections between endomorphin 2-immunoreactive terminals and μ-opioid receptor-expressing neurons in the sacral parasympathetic nucleus of the rat.

Dou XL, Qin RL, Qu J, Liao YH, Lu Yc, Zhang T, Shao C, Li YQ - PLoS ONE (2013)

Bottom Line: All of the them also expressed MOR.These results provided morphological evidence that EM2-containing axon terminals formed symmetric synapses with MOR-expressing PPNs in the SPN.The present results also show that EM2 and MOR might be involved in both the homeostatic control and information transmission of micturition.

View Article: PubMed Central - PubMed

Affiliation: Department of Urology, Xijing Hospital, The Fourth Military Medical University, Xi'an, China.

ABSTRACT
The urinary bladder is innervated by parasympathetic preganglionic neurons (PPNs) that express μ-opioid receptors (MOR) in the sacral parasympathetic nucleus (SPN) at lumbosacral segments L6-S1. The SPN also contains endomorphin 2 (EM2)-immunoreactive (IR) fibers and terminals. EM2 is the endogenous ligand of MOR. In the present study, retrograde tract-tracing with cholera toxin subunit b (CTb) or wheat germ agglutinin-conjugated horseradish peroxidase (WGA-HRP) via the pelvic nerve combined with immunohistochemical staining for EM2 and MOR to identify PPNs within the SPN as well as synaptic connections between the EM2-IR terminals and MOR-expressing PPNs in the SPN of the rat. After CTb was injected into the pelvic nerve, CTb retrogradely labeled neurons were almost exclusively located in the lateral part of the intermediolateral gray matter at L6-S1 of the lumbosacral spinal cord. All of the them also expressed MOR. EM2-IR terminals formed symmetric synapses with MOR-IR, WGA-HRP-labeled and WGA-HRP/MOR double-labeled neuronal cell bodies and dendrites within the SPN. These results provided morphological evidence that EM2-containing axon terminals formed symmetric synapses with MOR-expressing PPNs in the SPN. The present results also show that EM2 and MOR might be involved in both the homeostatic control and information transmission of micturition.

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Synaptic connections between EM2-IR axon terminals (containing DAB reaction products) and HRP-labeled neuronal cell body (containing TMB reaction products), MOR-IR (containing gold-silver grains) or HRP/MOR double-labeled dendrites (containing both TMB reaction products and gold-particles) of the PPNs in the SPN.Three EM2-IR axons made symmetric synaptic connections with an MOR-IR dendrite (A), an HRP retrograde-labeled neuronal cell body (B) and an HRP/MOR double-labeled dendrite (C) of the PPNs in the SPN. The scale bar indicates 0.3 µm in A–C.
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pone-0062028-g005: Synaptic connections between EM2-IR axon terminals (containing DAB reaction products) and HRP-labeled neuronal cell body (containing TMB reaction products), MOR-IR (containing gold-silver grains) or HRP/MOR double-labeled dendrites (containing both TMB reaction products and gold-particles) of the PPNs in the SPN.Three EM2-IR axons made symmetric synaptic connections with an MOR-IR dendrite (A), an HRP retrograde-labeled neuronal cell body (B) and an HRP/MOR double-labeled dendrite (C) of the PPNs in the SPN. The scale bar indicates 0.3 µm in A–C.

Mentions: Electron microscopy was used to confirm the existence of synaptic connections between the EM2-IR axon terminals and MOR-IR neurons, WGA-HRP-labeled neurons or WGA-HRP/MOR double-labeled neurons in the SPN (Figure 5). Using electron microscopy, the presence of heavily stained and predominantly homogeneous black substances (DAB reaction products) were distributed in the axoplasm and around synaptic vesicles (Figures 5A, B, C). After enhancement with the HQ Silver Kit, immunogold-labeling of black oval or round particles with high electron densities were found underneath the plasma membrane of the neuronal cell bodies and large dendritic processes (Figures 5A, C). In the present study, DAB reaction products, immunogold particles and TMB reaction products were used to label the EM2-IR axon terminals (Figures 5A, B, C), MOR-IR neurons (Figures 5A, C) and WGA-HRP retrograde-labeled neuronal cell bodies and their processes (Figures 5B, C), respectively.


Synaptic connections between endomorphin 2-immunoreactive terminals and μ-opioid receptor-expressing neurons in the sacral parasympathetic nucleus of the rat.

Dou XL, Qin RL, Qu J, Liao YH, Lu Yc, Zhang T, Shao C, Li YQ - PLoS ONE (2013)

Synaptic connections between EM2-IR axon terminals (containing DAB reaction products) and HRP-labeled neuronal cell body (containing TMB reaction products), MOR-IR (containing gold-silver grains) or HRP/MOR double-labeled dendrites (containing both TMB reaction products and gold-particles) of the PPNs in the SPN.Three EM2-IR axons made symmetric synaptic connections with an MOR-IR dendrite (A), an HRP retrograde-labeled neuronal cell body (B) and an HRP/MOR double-labeled dendrite (C) of the PPNs in the SPN. The scale bar indicates 0.3 µm in A–C.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3643968&req=5

pone-0062028-g005: Synaptic connections between EM2-IR axon terminals (containing DAB reaction products) and HRP-labeled neuronal cell body (containing TMB reaction products), MOR-IR (containing gold-silver grains) or HRP/MOR double-labeled dendrites (containing both TMB reaction products and gold-particles) of the PPNs in the SPN.Three EM2-IR axons made symmetric synaptic connections with an MOR-IR dendrite (A), an HRP retrograde-labeled neuronal cell body (B) and an HRP/MOR double-labeled dendrite (C) of the PPNs in the SPN. The scale bar indicates 0.3 µm in A–C.
Mentions: Electron microscopy was used to confirm the existence of synaptic connections between the EM2-IR axon terminals and MOR-IR neurons, WGA-HRP-labeled neurons or WGA-HRP/MOR double-labeled neurons in the SPN (Figure 5). Using electron microscopy, the presence of heavily stained and predominantly homogeneous black substances (DAB reaction products) were distributed in the axoplasm and around synaptic vesicles (Figures 5A, B, C). After enhancement with the HQ Silver Kit, immunogold-labeling of black oval or round particles with high electron densities were found underneath the plasma membrane of the neuronal cell bodies and large dendritic processes (Figures 5A, C). In the present study, DAB reaction products, immunogold particles and TMB reaction products were used to label the EM2-IR axon terminals (Figures 5A, B, C), MOR-IR neurons (Figures 5A, C) and WGA-HRP retrograde-labeled neuronal cell bodies and their processes (Figures 5B, C), respectively.

Bottom Line: All of the them also expressed MOR.These results provided morphological evidence that EM2-containing axon terminals formed symmetric synapses with MOR-expressing PPNs in the SPN.The present results also show that EM2 and MOR might be involved in both the homeostatic control and information transmission of micturition.

View Article: PubMed Central - PubMed

Affiliation: Department of Urology, Xijing Hospital, The Fourth Military Medical University, Xi'an, China.

ABSTRACT
The urinary bladder is innervated by parasympathetic preganglionic neurons (PPNs) that express μ-opioid receptors (MOR) in the sacral parasympathetic nucleus (SPN) at lumbosacral segments L6-S1. The SPN also contains endomorphin 2 (EM2)-immunoreactive (IR) fibers and terminals. EM2 is the endogenous ligand of MOR. In the present study, retrograde tract-tracing with cholera toxin subunit b (CTb) or wheat germ agglutinin-conjugated horseradish peroxidase (WGA-HRP) via the pelvic nerve combined with immunohistochemical staining for EM2 and MOR to identify PPNs within the SPN as well as synaptic connections between the EM2-IR terminals and MOR-expressing PPNs in the SPN of the rat. After CTb was injected into the pelvic nerve, CTb retrogradely labeled neurons were almost exclusively located in the lateral part of the intermediolateral gray matter at L6-S1 of the lumbosacral spinal cord. All of the them also expressed MOR. EM2-IR terminals formed symmetric synapses with MOR-IR, WGA-HRP-labeled and WGA-HRP/MOR double-labeled neuronal cell bodies and dendrites within the SPN. These results provided morphological evidence that EM2-containing axon terminals formed symmetric synapses with MOR-expressing PPNs in the SPN. The present results also show that EM2 and MOR might be involved in both the homeostatic control and information transmission of micturition.

Show MeSH
Related in: MedlinePlus