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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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Immunofluorescence double labeling of EM2 and MOR immunoreactivity in the SPN on transverse sections at S1.Low-magnification images of the immunofluorescence histochemical staining for EM2 (A1) and MOR (B1) in the SPN (indicated with squares). Scattered EM2-IR fibers and terminals (A2) and many MOR-IR neurons (B2) are observed in the SPN. EM2-IR axon terminals also appear to be closely apposed with the MOR-IR neurons (indicated with arrows) in the SPN (as indicated with a square in C1) (C2). The scale bars indicate 200 µm in A1, B1 and C1 and 40 µm in A2, B2 and C2.
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pone-0062028-g003: Immunofluorescence double labeling of EM2 and MOR immunoreactivity in the SPN on transverse sections at S1.Low-magnification images of the immunofluorescence histochemical staining for EM2 (A1) and MOR (B1) in the SPN (indicated with squares). Scattered EM2-IR fibers and terminals (A2) and many MOR-IR neurons (B2) are observed in the SPN. EM2-IR axon terminals also appear to be closely apposed with the MOR-IR neurons (indicated with arrows) in the SPN (as indicated with a square in C1) (C2). The scale bars indicate 200 µm in A1, B1 and C1 and 40 µm in A2, B2 and C2.

Mentions: Many MOR-immuonreactive (-IR) neurons and their processes were observed in the intermediolateral cell column, i.e., SPN (Figures 2A, 3B1). This expression pattern was similar to that described in a previous report [14]. In the SPN, MOR-IR products were widely distributed throughout all of the PPNs. These MOR-immunopositive neuronal cell bodies exhibited similar morphological features and their range in diameter was similar to that of CTb-labeled PPNs in the SPN at L6-S1. Most of these neurons were fusiform, triangular, or multipolar in shape; and were small to medium in size (ranging from 8–13 µm along the shorter axis and 10–22 µm along the longer axis) (Figures 2A′, 3B2). Intense MOR immunoreactivity was primarily observed in the neuronal cell bodies and their processes (Figures 2A′, 3B2).


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)

Immunofluorescence double labeling of EM2 and MOR immunoreactivity in the SPN on transverse sections at S1.Low-magnification images of the immunofluorescence histochemical staining for EM2 (A1) and MOR (B1) in the SPN (indicated with squares). Scattered EM2-IR fibers and terminals (A2) and many MOR-IR neurons (B2) are observed in the SPN. EM2-IR axon terminals also appear to be closely apposed with the MOR-IR neurons (indicated with arrows) in the SPN (as indicated with a square in C1) (C2). The scale bars indicate 200 µm in A1, B1 and C1 and 40 µm in A2, B2 and C2.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3643968&req=5

pone-0062028-g003: Immunofluorescence double labeling of EM2 and MOR immunoreactivity in the SPN on transverse sections at S1.Low-magnification images of the immunofluorescence histochemical staining for EM2 (A1) and MOR (B1) in the SPN (indicated with squares). Scattered EM2-IR fibers and terminals (A2) and many MOR-IR neurons (B2) are observed in the SPN. EM2-IR axon terminals also appear to be closely apposed with the MOR-IR neurons (indicated with arrows) in the SPN (as indicated with a square in C1) (C2). The scale bars indicate 200 µm in A1, B1 and C1 and 40 µm in A2, B2 and C2.
Mentions: Many MOR-immuonreactive (-IR) neurons and their processes were observed in the intermediolateral cell column, i.e., SPN (Figures 2A, 3B1). This expression pattern was similar to that described in a previous report [14]. In the SPN, MOR-IR products were widely distributed throughout all of the PPNs. These MOR-immunopositive neuronal cell bodies exhibited similar morphological features and their range in diameter was similar to that of CTb-labeled PPNs in the SPN at L6-S1. Most of these neurons were fusiform, triangular, or multipolar in shape; and were small to medium in size (ranging from 8–13 µm along the shorter axis and 10–22 µm along the longer axis) (Figures 2A′, 3B2). Intense MOR immunoreactivity was primarily observed in the neuronal cell bodies and their processes (Figures 2A′, 3B2).

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