Abstract
Intraplantar (i.pl.) injections of thymulin have been shown to produce hyperalgesia in rats through a prostaglandin E2-dependent mechanism. This study aimed at investigating if such injections can produce sustained activation of spinal neurons by mapping the fos-like-immunoreactivity (FLI) as a marker for this activation. Our results showed that thymulin produces significant and sustained FLI in neurons located in spinal laminae known to be involved in nociception. Pretreatment with either morphine or meloxicam (a cyclooxygenase inhibitor) revealed differential effects on FLI and the hyperalgesia induced by thymulin. These findings support the hypothesis that thymulin can affect central neurons either directly or through the peripheral nerve terminals.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Antibodies
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Cyclooxygenase Inhibitors / pharmacology*
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Hot Temperature
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Hyperalgesia / chemically induced
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Hyperalgesia / immunology
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Meloxicam
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Morphine / pharmacology*
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Narcotics / pharmacology*
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Peripheral Nerves / drug effects
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Peripheral Nerves / immunology
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Physical Stimulation
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Prostaglandin-Endoperoxide Synthases / metabolism
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Proto-Oncogene Proteins c-fos / analysis
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Proto-Oncogene Proteins c-fos / biosynthesis*
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Proto-Oncogene Proteins c-fos / immunology
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Rats
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Rats, Sprague-Dawley
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Spinal Cord / chemistry
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Spinal Cord / drug effects*
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Spinal Cord / enzymology
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Thiazines / pharmacology*
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Thiazoles / pharmacology*
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Thymic Factor, Circulating / immunology
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Thymic Factor, Circulating / pharmacology*
Substances
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Antibodies
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Cyclooxygenase Inhibitors
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Narcotics
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Proto-Oncogene Proteins c-fos
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Thiazines
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Thiazoles
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Morphine
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Thymic Factor, Circulating
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Prostaglandin-Endoperoxide Synthases
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Meloxicam