[Effect of beta-endorphin on plasma sialic acid level in rats and the relationship with the immune function]

With the use of beta-EP microinjection into the central nervous system, spectrophotometrical analysis and immunochemical method we studied the effect of beta-Endorphin (beta-EP) on plasma sialic acid (SA) level. The results indicate: (1) The plasma SA level was significantly decreased after microinjection of beta-EP into the lateral ventricle (LV); (2) When beta-EP was microinjection into nucleus arcuatus (ARC), the plasma SA level was significantly decreased (P < 0.05). This effect can be blocked by i.v. atropine or vagotomy; (3) Microinjection of beta-EP into ARC can cause the increase of CD3, CD4 and CD4/CD8, while CD8 was decreased. The above results suggest that the possible mechanism underlying the decrease of plasma SA level is mediated by cholinergic muscarinic receptor, and the cellular immune function is enhanced.