Determination of Biological Activity of Gonadotrophins in Randombred and Sprague Dawley Rats. Part 2. Determination of Biological Activity of Luteinising Hormone

INTRODUCTION. The tendency towards reducing the use of laboratory animals in pharmaceutical quality assessment, along with the development of new technologies for gonadotrophin production, necessitate the development of novel assays to determine the biological activity of natural and recombinant anterior pituitary preparations.

AIM. This study aimed to select the optimum conditions for the determination of the biological activity of luteinising hormone (LH) in urinary and genetically engineered LH preparations by tests in randombred and Sprague Dawley rats.

MATERIALS AND METHODS. The biological activity of urinary and recombinant LH preparations was determined in vivo in a three-dose randomised Steelman–Pohley bioassay, which compared the biological activity of the test samples to a reference standard (RS). The analysis used two years’ worth of test results. The RS used was the WHO international standard containing 183 IU of follicle stimulating hormone bioactivity and 177 IU of LH bioactivity per ampoule. The bioassay was performed in immature male randombred and Sprague Dawley rats; the bioassay conditions were selected according to the rat type.

RESULTS. The results of the in vivo determination of LH biological activity in male rats were compared by the standard deviation to slope ratio (s/b), which helps estimate response variation and dose dependence at the same time. The study demonstrated the possibility of using Sprague Dawley rats (s/b=0.82±0.44) for the determination of LH biological activity along with randombred animals (s/b=0.68±0.58). The s/b ratios were close, although Sprague Dawley rats and randombred rats were used in the assay at a 1:2 ratio.

CONCLUSIONS. It is possible to determine the biological activity of LH from menopausal gonadotrophin preparations in both randombred and Sprague Dawley male rats. The use of Sprague Dawley rats for testing can confirm the reliability of test results using fewer animals than needed for standard tests; this is not only humane but also cost effective.

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