M. Ahmed et al., NEUROPEPTIDE Y-LIKE AND VASOACTIVE INTESTINAL POLYPEPTIDE-LIKE IMMUNOREACTIVITY IN ADJUVANT ARTHRITIS - EFFECTS OF CAPSAICIN TREATMENT, Neuropeptides, 29(1), 1995, pp. 33-43
The occurrence of the neuropeptides vasoactive intestinal polypeptide
(VIP) and neuropeptide Y (NPY) in ankle joints and dorsal root ganglia
(L2-L6) was analyzed in normal and arthritic Lewis rats. In addition
the effect of capsaicin pretreatment was investigated. The study inclu
ded 92 rats consisting of 4 groups, 23 rats in each; normal rats, norm
al rats given capsaicin, arthritic rats and arthritic rats pretreated
with capsaicin. The localization of the neuropeptides was assessed by
immunohistochemistry and the tissue concentrations were determined by
radioimmunoassay (RIA). In the arthritic rats, there was a slight incr
ease in NPY immunoreactive nerve fibres in the ankle joint synovium an
d bone marrow, as compared to normal rats. Notably, there was an inten
se fluorescence and significant increase (p <0.01, 41%) in the number
of NPY-positive megakaryocytes in the tibial bone marrow of arthritic
rats. RIA showed that the concentration of NPY-like immunoreactivity (
LI) was increased by 50% in the ankle joint. Pretreatment with capsaic
in did not affect the increased level of NPY-LI in the ankle joint of
arthritic rats. The concentration of NPY-LI in the dorsal root ganglia
was not altered in arthritic rats, nor was it affected by the capsaic
in treatment. No NPY immunoreactive cells could be detected in the dor
sal root ganglia. The number of VIP immunoreactive nerve fibres observ
ed in ankle joints of arthritic and normal rats did not differ. Howeve
r,, RIA measurements showed an 11% increase in the VIP concentration i
n arthritic rats, which was unaffected by capsaicin treatment. In dors
al root ganglia, RIA disclosed a 21% increase in VIP-LI, although no V
IP-positive cells could be detected. Capsaicin treatment did not affec
t the increased concentration of VIP-LI in the dorsal root ganglia.