EN
In 1983 prof. Boguslaw Sadowski from Institute of Genetic and Animal Breeding in Jastrzebiec developed genetic mouse lines selectively bred for high (HA) and low (LA) swim-stress induced analgesia. Selected animals differ in sensitivity to both, pain or stress responses. Many experiments were conducted but the mechanism which is responsible for different sensitivity to both, pain and stress in these animals has been unknown till today. We hypothesized that difference in blood-brain barrier (BBB) permeability is the reason of different response of HA and LA mice. According to our hypothesis the β-endorphins which are released on the periphery after stressful stimuli, can cross the BBB and reach the brain, and analgesia is observed. The aim of the studies is to present the analgesic activity of opioid compounds in selected mice to examine their BBB permeability. This communication will also present infl uence of stress on analgesic activity of the given compounds. Different analgesic potency of alkaloid and opioid peptide in selected mice was a premise to conduct an ultramicroscopic studies which displayed pathological changes in morphology of BBB in HA and LA mice. These fi ndings may explain different analgesic potency of the given compounds. These animals may well simulate human high and low sensitivity to both, pain or stress response. Presented studies have been supported with EU grant Normolife (LSHC-CT-2006-037733)