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Developmental alterations in nociceptive threshold, immunoreactive calcitonin gene-related peptide and substance P, and fluoride-resistant acid phosphatase in neonatally capsaicin-treated rats.
J Comp Neurol. 1991 Oct 15; 312(3):436-50.JC

Abstract

This study examined the effect of neonatal administration of capsaicin on nociceptive threshold and the distribution of calcitonin gene-related peptide (CGRP), substance P (SP), and fluoride-resistant acid phosphatase (FRAP) in the dorsal horn of the spinal cord during the course of development (10 days to 12 weeks of age) in the rat. As early as 10 days of age, CGRP-like immunoreactivity was reduced in laminae I, II, and V, as well as in the bundles of fibers situated dorsal and ventral to the central canal. However, beginning on or about 6 weeks of age, the density of CGRP-like immunoreactivity in the superficial laminae and in the bundles dorsal and ventral to the central canal increased. Moreover, thick, nonvaricose CGRP-like immunoreactive fibers appeared in laminae III and IV. These recurring fibers were of primary afferent origin as demonstrated by their disappearance after multiple, unilateral rhizotomies. A similar age-dependent alteration in the density of FRAP activity was also observed. Although virtually absent at 10 days of age after neonatal administration of capsaicin, the density of FRAP activity increased in lamina II by 8 weeks of age. This activity disappeared after multiple, unilateral rhizotomies, indicating that the FRAP activity that reappeared was of primary afferent origin. Neonatal administration of capsaicin also reduced the density of SP-like immunoreactivity in the dorsal horn as early as 10 days of age, although the density of SP-like immunoreactivity showed some recovery after 6 weeks of age. However, unlike CGRP-like immunoreactivity or FRAP activity, the density of SP-like immunoreactivity in capsaicin-treated rats was not detectably altered by multiple, unilateral rhizotomies, indicating that it originated principally from intrinsic dorsal horn neurons. Age-dependent alterations in both thermal and mechanical, but not chemical, nociceptive thresholds were also observed in these same animals. Thus, tail flick latency, hot plate latency, and paw withdrawal threshold were maximally increased at 6 weeks of age, after which time thresholds declined to vehicle-treated values. In contrast, capsaicin-treated animals were uniformly insensitive to ophthalmic administration of capsaicin. The correspondence between developmental alterations in CGRP-like immunoreactivity or FRAP activity and in thermal and mechanical nociceptive thresholds is suggestive of a role of CGRP- or FRAP-containing primary afferents in thermal and mechanical nociception.

Authors+Show Affiliations

Department of Central Nervous System Diseases Research, G.D. Searle & Co., Skokie, Illinois 60077.No affiliation info available

Pub Type(s)

Comparative Study
Journal Article

Language

eng

PubMed ID

1721077

Citation

Hammond, D L., and M A. Ruda. "Developmental Alterations in Nociceptive Threshold, Immunoreactive Calcitonin Gene-related Peptide and Substance P, and Fluoride-resistant Acid Phosphatase in Neonatally Capsaicin-treated Rats." The Journal of Comparative Neurology, vol. 312, no. 3, 1991, pp. 436-50.
Hammond DL, Ruda MA. Developmental alterations in nociceptive threshold, immunoreactive calcitonin gene-related peptide and substance P, and fluoride-resistant acid phosphatase in neonatally capsaicin-treated rats. J Comp Neurol. 1991;312(3):436-50.
Hammond, D. L., & Ruda, M. A. (1991). Developmental alterations in nociceptive threshold, immunoreactive calcitonin gene-related peptide and substance P, and fluoride-resistant acid phosphatase in neonatally capsaicin-treated rats. The Journal of Comparative Neurology, 312(3), 436-50.
Hammond DL, Ruda MA. Developmental Alterations in Nociceptive Threshold, Immunoreactive Calcitonin Gene-related Peptide and Substance P, and Fluoride-resistant Acid Phosphatase in Neonatally Capsaicin-treated Rats. J Comp Neurol. 1991 Oct 15;312(3):436-50. PubMed PMID: 1721077.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Developmental alterations in nociceptive threshold, immunoreactive calcitonin gene-related peptide and substance P, and fluoride-resistant acid phosphatase in neonatally capsaicin-treated rats. AU - Hammond,D L, AU - Ruda,M A, PY - 1991/10/15/pubmed PY - 1991/10/15/medline PY - 1991/10/15/entrez SP - 436 EP - 50 JF - The Journal of comparative neurology JO - J. Comp. Neurol. VL - 312 IS - 3 N2 - This study examined the effect of neonatal administration of capsaicin on nociceptive threshold and the distribution of calcitonin gene-related peptide (CGRP), substance P (SP), and fluoride-resistant acid phosphatase (FRAP) in the dorsal horn of the spinal cord during the course of development (10 days to 12 weeks of age) in the rat. As early as 10 days of age, CGRP-like immunoreactivity was reduced in laminae I, II, and V, as well as in the bundles of fibers situated dorsal and ventral to the central canal. However, beginning on or about 6 weeks of age, the density of CGRP-like immunoreactivity in the superficial laminae and in the bundles dorsal and ventral to the central canal increased. Moreover, thick, nonvaricose CGRP-like immunoreactive fibers appeared in laminae III and IV. These recurring fibers were of primary afferent origin as demonstrated by their disappearance after multiple, unilateral rhizotomies. A similar age-dependent alteration in the density of FRAP activity was also observed. Although virtually absent at 10 days of age after neonatal administration of capsaicin, the density of FRAP activity increased in lamina II by 8 weeks of age. This activity disappeared after multiple, unilateral rhizotomies, indicating that the FRAP activity that reappeared was of primary afferent origin. Neonatal administration of capsaicin also reduced the density of SP-like immunoreactivity in the dorsal horn as early as 10 days of age, although the density of SP-like immunoreactivity showed some recovery after 6 weeks of age. However, unlike CGRP-like immunoreactivity or FRAP activity, the density of SP-like immunoreactivity in capsaicin-treated rats was not detectably altered by multiple, unilateral rhizotomies, indicating that it originated principally from intrinsic dorsal horn neurons. Age-dependent alterations in both thermal and mechanical, but not chemical, nociceptive thresholds were also observed in these same animals. Thus, tail flick latency, hot plate latency, and paw withdrawal threshold were maximally increased at 6 weeks of age, after which time thresholds declined to vehicle-treated values. In contrast, capsaicin-treated animals were uniformly insensitive to ophthalmic administration of capsaicin. The correspondence between developmental alterations in CGRP-like immunoreactivity or FRAP activity and in thermal and mechanical nociceptive thresholds is suggestive of a role of CGRP- or FRAP-containing primary afferents in thermal and mechanical nociception. SN - 0021-9967 UR - https://www.unboundmedicine.com/medline/citation/1721077/Developmental_alterations_in_nociceptive_threshold_immunoreactive_calcitonin_gene_related_peptide_and_substance_P_and_fluoride_resistant_acid_phosphatase_in_neonatally_capsaicin_treated_rats_ L2 - https://onlinelibrary.wiley.com/resolve/openurl?genre=article&sid=nlm:pubmed&issn=0021-9967&date=1991&volume=312&issue=3&spage=436 DB - PRIME DP - Unbound Medicine ER -