Effect of negative limb pressure on spinal cord and dorsal root ganglion calcitonin gene-related peptide-immunoreactive nerve fibers in dogs with peripheral arterial occlusive disease

Jun YI; Mofan NING; Ling WANG; Rui LING; Zhong MA; Jianghao CHEN; Ting WANG

ABSTRACT

BACKGROUND:

Harmful stimuli induce increased production of calcitonin gene-related peptide(CGRP) in the spinal cord and dorsal root ganglion, causing also intense dilation of the microvessels. But it remains unknown whether vessel dilation and pain relief were accompanied by increased CGRP production when negative pressure is applied on the limbs for treatment of peripheral arterial occlusion diseases (PAOD).

OBJECTIVE:

To examine the changes of calcitonin gene-related peptide (GGRP) -immunoractive nerve fibers in the spinal cord and dorsal root ganglion in dogs with PAOD treated with negative pressure on the limbs.

DESIGN:

A randomized controlled retrospective study.

SETTING:

The department of general surgery of a military medical university.MATERIALS This study was carried out at Xijing Hospital of the Fourth Military Medical University of Chinese PLA between January and August 2003. Seventeen adult male dogs weighing 12 - 18 kg, regardless of the gender, were selected.

INTERVENTIONS:

Seventeen dogs were randomly divided into three groups, namely the treatment group( n = 10), model group( n = 5), and the normal control group( n = 2). Posterior left leg ischemia was induced in dogs in the treatment and model groups, and those in the treatment group, but not the model group, were treated with negative limb pressure for 10 days 14days after model establishment. The spinal cord and dorsal ganglion at L1-5of these two groups were collected and stained immunohistochemically for observing the changes of GGRP-immunreactive nerve fibers. The dogs in the normal control group were also sampled in similar manner for immunohistochemical staining.MAIN OUTCOME

MEASURES:

Distribution of CGRP-immunoreactive nerve fibers in the spinal cord and dorsal ganglions of the three groups of dogs.

RESULTS:

In the dogs of the model group, GGRP-immunoreactive nerve fibers in the spinal cord and dorsal ganglions was significantly more numerous[ (75. 00 ±4. 30)%, (68.20 ± 2.60)% ] than those in the treatment and normal control groups[ (58. 20 ±5. 10)%, (52. 20 ±6.20)%; (37.00±4. 20)%, (34. 00 ± 1.40)%, P ＜ 0.01]. The positive nerve fibers were less strongly stained in the treatment group than those in the model group,but still stronger stained those in the normal control group, with significant difference between the three groups( P ＜ 0.01).

CONCLUSION:

Negative pressure on the limbs may attenuate the synthesis of CGRP-immunoreactive nerve fibers in the spinal cord and dorsal root ganglion and pain conduction following PAOD in dogs, so that harmful afferent stimuli are inhibited to relieve the pain in the limbs.