The spinal release of immunoreactive neuropeptide Y in rats with a peripheral nerve injury

• Main Author: Mark, Margo Anne
• Published: University of Edinburgh 1997
• Subjects: 571.1
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.657320

The experiments in this thesis employed the antibody microprobe technique to study, both in normal rats and in those with a peripheral mononeuropathy, the spinal release of extracellular immunoreactive neuropeptide Y and to determine the origin of such release. In the initial experiments, microprobes bearing immobilised antibodies to neuropeptide Y were inserted into the lumbar spinal cord of urethane anaesthetised normal rats. In the absence of peripheral stimuli microprobes detected a high basal presence of immunoreactive NPY throughout the entire dorsal and ventral horn. Electrical stimulator of large diameter afferents of the ipsilateral sciatic nerve and unmyelinated primary afferents did not significantly alter the spinal release of immunoreactive neuropeptide Y in the spinal cord. Transection of the spinal cord at a low thoracic level resulted in increased levels of immunoreactive neuropeptide Y only in the lower ventral horn. The predominant failure of electrical stimulation and of spinalisation to significantly alter the basal levels of immunoreactive neuropeptide Y suggests that the latter results from spontaneous activity in intrinsic neurones. For studies of rats with a peripheral mononeuropathy, the model of Bennett & Xie was used. Postoperatively the development of mechanical allodynia and hyperalgesia were assessed and animals used at 10-14 days only if they displayed the characteristic behavioural signs associated with this model. In sham animals both sides of the lumbar spinal cord showed a significant spinal release of immunoreactive neuropeptide Y throughout the entire dorsal horn. The site of greatest extracellular levels was the superficial dorsal horn. A similar distribution was also found in the neuropathic animal on the side contralateral to the nerve ligation. On the ipsilateral side of the neuropathic rat however there was a further zone of spontaneous release of immunoreactive neuropeptide Y in the mid and lower dorsal horn (approximately to laminae III, IV and V).