6533b86ffe1ef96bd12cd0a2

RESEARCH PRODUCT

Gender- and season-dependent relationships between testosterone, oestradiol and immune functions in wild roach

subject

description

Plasma testosterone and 17β-oestradiol concentrations, differential leukocyte counts and proportion of dead Rhipidocotyle campanula gill parasites (parasite resistance) were determined five times during a year in two populations of roach Rutilus rutilus and analysed for seasonal and gender differences. In addition to the above immune variables, plasma Immunoglobulin M (IgM) concentration, chemiluminescence and migration differential of head kidney phagocytes, size of the spleen, haematocrit and total leukocyte count were correlated with sex hormones for each population, sampling time and sex separately, using condition factor as a partial correlate. There were no clear gender differences in the determined immune variables. Both testosterone and oestradiol concentrations were lowest after the spawning in June. Oestradiol was higher in females than in males, but testosterone was present in equal concentrations in both sexes. Statistically significant correlations between sex hormones and immune variables were rare and mainly without any patterns with respect to population, sex or sampling date. The meta-analysis on individual correlations, however, revealed a positive relationship of plasma testosterone concentration to chemiluminescence of head kidney phagocytes, plasma IgM concentration and the proportion of dead R. campanula to all R. campanula on the gills. In the meta-analysis, the concentration of oestradiol was not found to correlate with any of the studied immune variables.