The action of capsaicin on primary afferent central terminals in the superficial dorsal horn of newborn mice.

Abstract

Capsaicin was injected subcutaneously (50 mg/kg) into 10 mice on days 2 or 3 after birth, and 12 h, 3 and 5 days later the distribution and structure of degenerated primary afferent central axons or terminals (C-terminals) in the lumbar spinal dorsal horn were examined by electron microscopy. Degenerated terminal axons with dense or lamellar bodies or higher electron density were conspicuous 12h after treatment with capsaicin. Severely degenerated unmyelinated axons, including dense or lamellar bodies engulfed by micro

GABAergic neurons in the mouse superficial dorsal horn with special emphasis on their relation to primary afferent central terminals.

“…We demonstrated the same types of C-terminals in the mouse superficial dorsal horn (HIURA et al, 1990). Recently, there have been a few reports on the morphological relationship between GABAergic neurons and C-terminals.…”

“…However, as we observed previously (HIURA et al, 1990) CI-terminals are not always electron dense, even in adults. Furthermore, not the all CH-terminals RIBEIRO-DA-SILVA and COIMBRA (1982).…”

Fluoride-Resistant Acid Phosphatase (FRAP)-Positive Primary Afferent Central Terminals in the Mouse Substantia Gelatinosa.

“…From these results, they suggest that FRAP is related to the processing of nociceptive impulses. The present results showed that FRAP-positive terminals are synonymous with the various types of CI terminals sensitive to capsaicin [6][7][8]. Further, FRAPreactive CII-terminals also support the existence of capsaicin-sensitive CII-terminals [6,8].…”

FRAP-positive and Capsaicin-Sensitive Terminals in the Substantia Gelatinosa of the Mouse Spinal Trigeminal Nucleus Caudalis

“…These two types of the degenerated figures are compatible with the previous report (Hiura andIshizuka, 1994, 1995). The ultrastructural contours of degenerated terminals are the same as seen in the superficial dorsal horn of the mouse spinal cord (Hiura et aL, 1990;: dark, sinuous, slender, cap-like and scalloped with fully packed clear synaptic vesicles of various sizes, few dense core vesicles and mitochondria. Thus, the fine structures of capsaicin-sensitive and FRAP-positive terminals in the substantia gelatinosa of the mouse STNC were very similar to those in the superficial spinal dorsal horn of the mouse.…”