Subcellular distribution of two enzymes with neuropeptide converting activity in rat spinal cord

Cerebrospinal fluid dynorphin-converting enzyme activity is increased by voluntary exercise in the spontaneously hypertensive rat

The activity in cerebrospinal fluid (CSF) of dynorphin-converting enzyme (DCE) has been studied after voluntary exercise in the spontaneously hypertensive (SH) rat. The exercise consisted of spontaneous running in wheels for 4-5 weeks and the average running distance during the last two weeks was 4.0 km/24h. CSF samples were obtained under anaesthesia from the cisterna magna after penetration of the atlanto-occipital membrane. DCE transforms the members of the dynorphin family of opioid peptides into Leu-enkephalin-Arg6. In the present investigation a radioimmunoassay was used for quantitation of Leu-enkephalin-Arg6 release from dynorphin A1-17 and dynorphin B1-13. The rats that were running had a DCE activity (vs. both substrates) in CSF that was approximately 6-12 times higher than in animals not given the running opportunity. A statistically significant correlation between the two prodynorphin-derived substrate peptides was found in terms of DCE activity. We therefore propose that a single enzyme activity may be responsible for the hydrolysis of dynorphin B1-13 and dynorphin A1-17. Furthermore, a significant correlation was also found between running activity and DCE activity 12-14 h before the CSF was withdrawn. Besides measurement of DCE activity by radioimmunoassay, the formation of Leu-enkephalin-Arg6 was identified by reversed-phase micro-column liquid chromatography and plasma desorption mass spectrometry. The experiment shows that voluntary exercise affects opioid peptidergic mechanisms.

Decreased neuropeptide-converting enzyme activities in cerebrospinal fluid during acute but not chronic phases of collagen induced arthritis in rats

We investigated the effects of collagen II-induced arthritis on two cerebrospinal fluid (CSF) enzymes converting dynorphin A and substance P (SP), namely dynorphin-converting enzyme (DCE) and substance P endopeptidase (SPE). The products generated by these enzymes are the bioactive fragments Leu-enkephalin-Arg6 and substance P, respectively. The strain used (DA rats) is very sensitive towards induction of arthritis. The collagen arthritis is a chronic autoimmune arthritis induced by native rat collagen type II (CII). Following intradermal injection of CII into the tailbase. CSF was sampled on day 21 (acute arthritis) and day 38 (chronic arthritis). Control rats were untreated because the strain used developed an acute and self-limited arthritis (adjuvant arthritis) when administered vehicle (i.e. incomplete Freund's adjuvant). The DCE activity was significantly lowered in the acute phase of arthritis (P less than 0.05) when analysed with two-factor analysis of variance (ANOVA). The enzyme converting SP (SPE) also showed a significant decrease in the acute phase of arthritis (P less than 0.05). These results demonstrate that both DCE and SPE are affected in the acute phase of arthritis. A functional role of these enzymes in processing pain-related neuropeptides is therefore implicated.