Elsevier

Neuroscience

Volume 129, Issue 2, 2004, Pages 431-437
Neuroscience

Central projections of sensory innervation of the rat superior sagittal sinus

https://doi.org/10.1016/j.neuroscience.2004.07.045Get rights and content

Abstract

The central projections of the rat superior sagittal sinus (SSS) sensory innervation were studied by transganglionic tract tracing techniques. Cholera toxin subunit b (CTb) or wheat germ agglutinin–horseradish peroxidase conjugate (WGA–HRP) was applied on the overlying dura of the SSS and labeled terminations in the brainstem and cervical spinal cord were examined under the light microscope. Labeled cell bodies were seen bilaterally in the trigeminal ganglia and in the C2 dorsal root ganglia following both CTb and WGA–HRP applications. In the brainstem, labeled terminations were mainly found in the caudal and interpolar parts of the spinal trigeminal nucleus. In the CTb cases, terminations were also found in the dorsolateral part of the cuneate nucleus. In the spinal cord, labeled terminations were primarily located in the most ventrolateral part of the C1–C3 spinal dorsal horns on both sides. WGA–HRP labeled terminations were mainly located in laminae I and II, whereas CTb-labeled terminations located in laminae III and IV. These results indicate that the sensory information from the SSS is transmitted through both trigeminal and cervical spinal nerve branches to a primary sensory nervous center that extends from the C3 dorsal horn until to the interpolar part of the spinal trigeminal nucleus.

Section snippets

Experimental procedures

Sixteen adult male Sprague–Dawley rats weighing 280–400 g were used in this study. The animals received food and water ad libitum and were kept in a 12-h light/dark cycle at a constant environmental room temperature. Experimental procedures were approved in advance by the Animal Care and Use Committee of Malmö/Lund.All experiments conformed in accordance with the European Communities Council Directive of 24 November 1986 (86/609/EEC). All efforts were made to minimize the number of animals used

Labeling of the SSS and ganglia

Examination of the application sites showed that in most cases intense CTb or WGA–HRP labeling was limited to the adventitia of the SSS and the immediately adjacent dura. In one of the WGA–HRP cases, the tracer spread slightly into neighboring dura. As described below, the transganglionic labeling pattern in this case was somewhat different from that seen in the other cases.

In both the CTb and WGA–HRP cases, numerous labeled cell bodies were observed bilaterally in the TGs and C2 DRGs (Fig. 2A1,

Technical considerations

In the present study we examined the central projections of the SSS sensory innervation in rat using transganglionic tract tracing techniques. CTb or choleragenoid-conjugated horseradish peroxidase (B-HRP) label both large and small diameter myelinated A-fibers, which mainly originate from low threshold mechanoreceptors and terminate in the deep part (laminae III–V) of the spinal dorsal horn. WGA–HRP preferentially labels unmyelinated C-fibers which terminate in the superficial layers (laminae

Acknowledgments

This project was supported by the Swedish Research Council (Project Nos. 5958 and 14276).

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