Determination of biological activity of gonadotrophins in inbred and outbred animals. Part 1: Determination of biological activity of follicle-stimulating hormone

Abstract

Scientific relevance. The biological activity of medicinal products may vary depending on the method of production (i.e. biological or recombinant products). The widening variety of gonadotrophin preparations, the diversity of their production methods, and the irreplaceability of biological activity bioassays with physicochemical tests require improvement of animal testing conditions.Aim. This study aimed to determine the biological activity of follicle-stimulating hormone (FSH) in several rat lines, analyse the findings, and select the most optimal testing conditions.Materials and methods. The biological activity was determined using in vivo methods. The comparative analysis used test results obtained over several years in inbred and outbred rats treated with FSH. In all cases, the authors used a three-dose randomised method based on the determination of the biological activity of test samples by comparison with that of the WHO international standard (IS) containing 183 IU of FSH bioactivity and 177 IU of LH bioactivity per ampoule (NIBSC code: 10/286). The study included immature female rats, inbred (Wistar-Kyoto or Sprague Dawley) and outbred. Testing conditions depended on the selected rat line, with the main variables being the test dose and the number of animals per group.Results. The authors compared responses of inbred and outbred rats to various doses of the FSH IS and test samples. Given the narrow range of the analytical procedure, Wistar-Kyoto rats showed a relatively weak dose–response relationship. The study demonstrated that the doses and testing duration depended on the sensitivity of the animals. Test results were less variable in inbred rats than in outbred ones. The statistical analysis of the results of FSH bioactivity testing in inbred and outbred rats showed that, with inbred rats, the number of animals could be halved without compromising the validity of the test.Conclusions. The approach proposed in this study provides for testing the biological activity of FSH with fewer experimental animals, improved cost-effectiveness, and the same reliability of results.