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Distribution of raphespinal fibers in the mouse spinal cord.

Liang H, Wang S, Francis R, Whan R, Watson C, Paxinos G - Mol Pain (2015)

Bottom Line: We found that raphespinal fibers terminate in both the dorsal and ventral horns in addition to lamina 10.Immunofluorescence staining showed that raphespinal fibers were heterogeneous and serotoninergic fibers were present in all laminae but mainly in laminae 1, 2, medial lamina 8, laminae 9 and 10.The present study provides anatomical foundation for the multiple roles raphe and adjacent reticular nuclei play.

View Article: PubMed Central - PubMed

Affiliation: Neuroscience Research Australia, 139 Barker Street, Randwick, NSW, 2031, Australia. h.liang@neura.edu.au.

ABSTRACT

Background: Serotonergic raphespinal neurons and their fibers have been mapped in large mammals, but the non-serotonergic ones have not been studied, especially in the mouse. The present study aimed to investigate the termination pattern of fibers arising from the hindbrain raphe and reticular nuclei which also have serotonergic neurons by injecting the anterograde tracer BDA into them.

Results: We found that raphespinal fibers terminate in both the dorsal and ventral horns in addition to lamina 10. There is a shift of the fibers in the ventral horn towards the dorsal and lateral part of the gray matter. Considerable variation in the termination pattern also exists between raphe nuclei with raphe magnus having more fibers terminating in the dorsal horn. Fibers from the adjacent gigantocellular reticular nucleus show similar termination pattern as those from the raphe nuclei with slight difference. Immunofluorescence staining showed that raphespinal fibers were heterogeneous and serotoninergic fibers were present in all laminae but mainly in laminae 1, 2, medial lamina 8, laminae 9 and 10. Surprisingly, immunofluorescence staining on clarified spinal cord tissue revealed that serotoninergic fibers formed bundles regularly in a short distance along the rostrocaudal axis in the medial part of the ventral horn and they extended towards the lateral motor neuron column area.

Conclusion: Serotonergic and non-serotonergic fibers arising from the hindbrain raphe and reticular nuclei had similar termination pattern in the mouse spinal cord with subtle difference. The present study provides anatomical foundation for the multiple roles raphe and adjacent reticular nuclei play.

No MeSH data available.


Related in: MedlinePlus

Termination pattern of BDA labeled fibers arising from RPa and ROb. a–c An injection site in RPa and ROb, which involved the dorsal paragigantocellular reticular nucleus (red dashed circle). d A C8 section showing the labelled fibers in both the ventral and lateral funiculi (red arrows). e A C8 section showing labeled fibers in both the ventral and lateral funiculi (red arrows) and the medial lamina 7, and 8, and lamina 10. f A higher magnification of the rectangular area in e. Note labeled fibers in medial laminae 7, 8, and 9, and 10. g An L4 section showing labeled fibers in both the ventral and lateral funiculi (red arrows). Note there are more fibers in the lateral funiculus than in the ventral funiculus. h An L4 section showing labeled fibers in the lateral funiculus and in laminae 6–10. i A higher magnification of the rectangular area in h. j An S1 section showing labeled fibers in the lateral and ventral funiculi and in laminae 6–10. Note there are more fibers in the lateral funiculus than in the ventral funiculus. k A higher magnification of the rectangular area in j. l A T4 section showing labeled fibers in laminae 7–10 (red arrows). The scale bar 500 μm in a–c, 400 μm in d and g, 200 μm in e, h, and j, 100 μm in f, i, k, l and the microphotograph in c.
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Fig1: Termination pattern of BDA labeled fibers arising from RPa and ROb. a–c An injection site in RPa and ROb, which involved the dorsal paragigantocellular reticular nucleus (red dashed circle). d A C8 section showing the labelled fibers in both the ventral and lateral funiculi (red arrows). e A C8 section showing labeled fibers in both the ventral and lateral funiculi (red arrows) and the medial lamina 7, and 8, and lamina 10. f A higher magnification of the rectangular area in e. Note labeled fibers in medial laminae 7, 8, and 9, and 10. g An L4 section showing labeled fibers in both the ventral and lateral funiculi (red arrows). Note there are more fibers in the lateral funiculus than in the ventral funiculus. h An L4 section showing labeled fibers in the lateral funiculus and in laminae 6–10. i A higher magnification of the rectangular area in h. j An S1 section showing labeled fibers in the lateral and ventral funiculi and in laminae 6–10. Note there are more fibers in the lateral funiculus than in the ventral funiculus. k A higher magnification of the rectangular area in j. l A T4 section showing labeled fibers in laminae 7–10 (red arrows). The scale bar 500 μm in a–c, 400 μm in d and g, 200 μm in e, h, and j, 100 μm in f, i, k, l and the microphotograph in c.

Mentions: After injecting BDA to the raphe pallidus nucleus (RPa) and raphe obscurus nucleus (Rob) nuclei at the level of the rostral vagus nerve nucleus (10N) (Figure 1a–c), labeled fibers were found in the ventral portion of the ventral funiculus, and to a lesser extent, in the lateral funiculus bilaterally in the cervical segments (Figure 1d–f). In the thoracic and lower segments, the density of labeled fibers in the ventral funiculus decreased (82 ± 9 in cervical, 43 ± 7 in thoracic, 40 ± 6 in lumbar, 15 ± 3 in sacral cord), whereas the density of labeled fibers in the dorsolateral funiculus increased (19 ± 4 in cervical, 33 ± 6 in thoracic, 35 ± 5 in lumbar, 41 ± 5 in sacral) (Figure 1g–l).Figure 1


Distribution of raphespinal fibers in the mouse spinal cord.

Liang H, Wang S, Francis R, Whan R, Watson C, Paxinos G - Mol Pain (2015)

Termination pattern of BDA labeled fibers arising from RPa and ROb. a–c An injection site in RPa and ROb, which involved the dorsal paragigantocellular reticular nucleus (red dashed circle). d A C8 section showing the labelled fibers in both the ventral and lateral funiculi (red arrows). e A C8 section showing labeled fibers in both the ventral and lateral funiculi (red arrows) and the medial lamina 7, and 8, and lamina 10. f A higher magnification of the rectangular area in e. Note labeled fibers in medial laminae 7, 8, and 9, and 10. g An L4 section showing labeled fibers in both the ventral and lateral funiculi (red arrows). Note there are more fibers in the lateral funiculus than in the ventral funiculus. h An L4 section showing labeled fibers in the lateral funiculus and in laminae 6–10. i A higher magnification of the rectangular area in h. j An S1 section showing labeled fibers in the lateral and ventral funiculi and in laminae 6–10. Note there are more fibers in the lateral funiculus than in the ventral funiculus. k A higher magnification of the rectangular area in j. l A T4 section showing labeled fibers in laminae 7–10 (red arrows). The scale bar 500 μm in a–c, 400 μm in d and g, 200 μm in e, h, and j, 100 μm in f, i, k, l and the microphotograph in c.
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Related In: Results  -  Collection

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Fig1: Termination pattern of BDA labeled fibers arising from RPa and ROb. a–c An injection site in RPa and ROb, which involved the dorsal paragigantocellular reticular nucleus (red dashed circle). d A C8 section showing the labelled fibers in both the ventral and lateral funiculi (red arrows). e A C8 section showing labeled fibers in both the ventral and lateral funiculi (red arrows) and the medial lamina 7, and 8, and lamina 10. f A higher magnification of the rectangular area in e. Note labeled fibers in medial laminae 7, 8, and 9, and 10. g An L4 section showing labeled fibers in both the ventral and lateral funiculi (red arrows). Note there are more fibers in the lateral funiculus than in the ventral funiculus. h An L4 section showing labeled fibers in the lateral funiculus and in laminae 6–10. i A higher magnification of the rectangular area in h. j An S1 section showing labeled fibers in the lateral and ventral funiculi and in laminae 6–10. Note there are more fibers in the lateral funiculus than in the ventral funiculus. k A higher magnification of the rectangular area in j. l A T4 section showing labeled fibers in laminae 7–10 (red arrows). The scale bar 500 μm in a–c, 400 μm in d and g, 200 μm in e, h, and j, 100 μm in f, i, k, l and the microphotograph in c.
Mentions: After injecting BDA to the raphe pallidus nucleus (RPa) and raphe obscurus nucleus (Rob) nuclei at the level of the rostral vagus nerve nucleus (10N) (Figure 1a–c), labeled fibers were found in the ventral portion of the ventral funiculus, and to a lesser extent, in the lateral funiculus bilaterally in the cervical segments (Figure 1d–f). In the thoracic and lower segments, the density of labeled fibers in the ventral funiculus decreased (82 ± 9 in cervical, 43 ± 7 in thoracic, 40 ± 6 in lumbar, 15 ± 3 in sacral cord), whereas the density of labeled fibers in the dorsolateral funiculus increased (19 ± 4 in cervical, 33 ± 6 in thoracic, 35 ± 5 in lumbar, 41 ± 5 in sacral) (Figure 1g–l).Figure 1

Bottom Line: We found that raphespinal fibers terminate in both the dorsal and ventral horns in addition to lamina 10.Immunofluorescence staining showed that raphespinal fibers were heterogeneous and serotoninergic fibers were present in all laminae but mainly in laminae 1, 2, medial lamina 8, laminae 9 and 10.The present study provides anatomical foundation for the multiple roles raphe and adjacent reticular nuclei play.

View Article: PubMed Central - PubMed

Affiliation: Neuroscience Research Australia, 139 Barker Street, Randwick, NSW, 2031, Australia. h.liang@neura.edu.au.

ABSTRACT

Background: Serotonergic raphespinal neurons and their fibers have been mapped in large mammals, but the non-serotonergic ones have not been studied, especially in the mouse. The present study aimed to investigate the termination pattern of fibers arising from the hindbrain raphe and reticular nuclei which also have serotonergic neurons by injecting the anterograde tracer BDA into them.

Results: We found that raphespinal fibers terminate in both the dorsal and ventral horns in addition to lamina 10. There is a shift of the fibers in the ventral horn towards the dorsal and lateral part of the gray matter. Considerable variation in the termination pattern also exists between raphe nuclei with raphe magnus having more fibers terminating in the dorsal horn. Fibers from the adjacent gigantocellular reticular nucleus show similar termination pattern as those from the raphe nuclei with slight difference. Immunofluorescence staining showed that raphespinal fibers were heterogeneous and serotoninergic fibers were present in all laminae but mainly in laminae 1, 2, medial lamina 8, laminae 9 and 10. Surprisingly, immunofluorescence staining on clarified spinal cord tissue revealed that serotoninergic fibers formed bundles regularly in a short distance along the rostrocaudal axis in the medial part of the ventral horn and they extended towards the lateral motor neuron column area.

Conclusion: Serotonergic and non-serotonergic fibers arising from the hindbrain raphe and reticular nuclei had similar termination pattern in the mouse spinal cord with subtle difference. The present study provides anatomical foundation for the multiple roles raphe and adjacent reticular nuclei play.

No MeSH data available.


Related in: MedlinePlus