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Reduced substance P in hereditary sensory neuropathy in the mf rat
Abstract:
Mutilated foot (mf) is a mutant rat with an autosomal recessive sensory neuropathy. Affected animals become ataxic and their feet become mutilated. Morphological and quantitative studies have shown a reduced number of sensory ganglion cells and of cells of secondary sensory neurons. No degeneration was seen in the peripheral nervous system. Substance P (SP) is an undecapeptide which is thought to be involved in transmission of nociceptive information. Since mf rats show, in addition to ataxia, a decreased response to painful stimuli, SP immunoreactivity was examined. The density of SP staining was decreased at all levels of the spinal cord, mainly at cervical and lumbar levels and only in areas related to sensory pathways. In other areas of the spinal cord and in the substantia gelatinosa of the trigeminal tract, no reduction of SP staining was observed. The results further support the relationship between SP and transmission of pain stimuli. There are also many similarities between the appearance in mf rats and those in animals in which sensory afferents from dorsal root ganglia had been impaired with various methods, particularly in those treated from birth with capsaicin.
Insights
Mutilated foot rats exhibit sensory neuropathy, leading to ataxia and reduced pain response. This study found decreased Substance P (SP) in their spinal cords, supporting SP's role in pain signaling.
Area of Science:
- Neuroscience
- Genetics
- Pain Research
Background:
- Mutilated foot (mf) is an autosomal recessive mutant rat exhibiting sensory neuropathy, ataxia, and foot mutilation.
- Morphological studies reveal a reduced number of sensory ganglion cells and secondary sensory neurons, with no peripheral nervous system degeneration.
Purpose of the Study:
- To investigate the role of Substance P (SP) in the sensory neuropathy of mf rats.
- To examine SP immunoreactivity in the spinal cord of mf rats due to their decreased response to painful stimuli.
Main Methods:
- Assessment of SP immunoreactivity in the spinal cord of mf rats at various levels.
- Comparative analysis with similar conditions in other animal models, including capsaicin treatment.
Main Results:
- A significant decrease in SP staining density was observed in the spinal cord of mf rats, primarily at cervical and lumbar levels within sensory pathways.
- No reduction in SP staining was noted in other spinal cord areas or the trigeminal tract's substantia gelatinosa.
Conclusions:
- The findings support a crucial role for SP in the transmission of nociceptive information.
- Similarities between mf rats and other models with impaired sensory afferents suggest a conserved mechanism in pain pathway dysfunction.