02163naa a2200229 a 450000100080000000500110000800800410001910000190006024501720007926000090025152014490026065000150170965000220172465000170174665000100176365000150177365000100178865000170179870000140181570000150182977300890184415218512023-06-28       1978    bl uuuu     u00u1 u    #d1 aGARNIER, D. H.  aAndrogen radioimmunoassay in the rambresults of direct plasma testosterone and dehydroepiandrosterone measurement and physiological evaluation.h[electronic resource]  c1978  aDifferent radioimmunoassays of testosterone (T) dehydroepiandrosterone (DHA) and 5 a-dihydrotestosterone (5 a-DHT) were investigated for ram plasma. Specificity of the antisera, lack of noticeable binding in plasma, very low levels of other androgens allow direct plasma RIA for DHA and T by the double antibody technique. The levels obtained by this simplified method are in agreement with those found after extraction alone, after extraction and celite chromatography and after quantification with a completely different technique such as gas chromatography. The within assay variabilities for T and DHA were 4.7 p. 100 and 4.6 p. 100 respectively but vary with the level of steroid in plasma. The inter assay variabilities of T were 9.5 p. 100 and 3.2 p. 100 for 1.5 and 11.6 ng/ml of plasma respectively. The antiserum for 5 a-DHT have a specificity such that, even after celite chromatography some androgens (5 p-DHT) may interfere. However determinations of 5 u/5 !-DHT amounts are possible. The physiological validations of direct plasma T and DHA RIA were studied in various conditions. The DHA plasma variations are similar to those of T in Ram from birth to puberty, but the levels are lower. DHA plasma levels show a seasonal variation as does testosterone. Variations within 24 hrs of these two androgens were in synchrony. The direct plasma T and DHA assays are useful and inexpensive tools to characterize ram testicular function.  aPhysiology  aRadioimmunoassays  aReproduction  aSheep  aFisiologia  aOvino  aReprodução1 aCOTTA, Y.1 aTERQUI, M.  tAnnales de Biologie Animale, Biochimie, Biophysiquegv. 18, n. 2A, p. 265-281, 1978.