Sex dependent antinociceptive activity and blood pressure changes in SHR, WKY and WAG rat strains after diclofenac treatment.

Antinociceptive action of diclofenac (non-opioid analgesic) was investigated in male and female normotensive (WKY) and genetically established hypertensive (SHR) and normotensive WAG. The drug was administered subcutaneously in doses of 10 mg/kg body weight and per os 20 mg/kg and 40 mg/kg. Statistically significant differences in pain threshold were reported between male and female rats of investigated strains. Phase of sex cycle in female rats was determined along with the pain threshold level. Arterial hypertension control in WAG and SHR female rats performed in parallel showed considerable changes in blood pressure after diclofenac administration in the estrus phase. There were several correlated effects in blood pressure and pain threshold after drugs administration. The results obtained may explain the non-uniformity in antinociceptive action of analgesics in both sexes during long-term therapy in different strains.