Domestic cat testicular aromatase activity as assessed by the tritiated water-release assay

Lower testicular tetosterone:17β-estradiol (T:E2) ratio was found in teratospermic domestic cats (<40% morphologically normal sperm). The aim of this study was to assess the reliability of the tritiated water-release assay (TWRA) to measure aromatase activity in domestic cat testes. Testicular T and E2 concentrations, measured by enzyme immunoassay, and sperm morphology were evaluated to verify the relationship between them. Aromatase activity was measured in microsomal fraction and in homogenates of cat testes. Rat ovaries and piglet testes were used for assay validation. Aromatase activity was not detected in cat testes microsomal fraction (n = 8), not even when the protein amount added to the assay was increased from 50 to 200 μg. In homogenates, however, it was detected (3.5 ± 0.5 pmol.g-1.h-1; n = 7), although in such low levels that no activity inhibition was detectedwhen homogenates were incubated with increasing fadrazole concentrations. Although none of the cats in this study were classified as teratospermic, some sperm defects were correlated with testicular T:E2 ratio (abnormal acrosome, r = -0.76) and with E2 concentration (proximal cytoplasmic droplet, r = 0.77). However, we did not find any correlation between aromatase activity and hormonalor sperm morphology data. To our knowledge this is the first demonstration of testicular aromatase activity in domestic cats. Despite that, due to the low aromatase activity measured and the lack of correlation with other reproductive data, we could not infer that TWRA is a reliable method to detect differences in testicular aromatase activity in normospermic cats. Perhaps this method could be used in teratospermic individuals that probably havean increased aromatase activity. As an alternative, we suggest that more sensitive techniques should be used to compare aromatase activity between normospermic and teratospermic cats.(AU)

Domestic cat testicular aromatase activity as assessed by the tritiated water-release assay

Lower testicular tetosterone:17β-estradiol (T:E2) ratio was found in teratospermic domestic cats (<40% morphologically normal sperm). The aim of this study was to assess the reliability of the tritiated water-release assay (TWRA) to measure aromatase activity in domestic cat testes. Testicular T and E2 concentrations, measured by enzyme immunoassay, and sperm morphology were evaluated to verify the relationship between them. Aromatase activity was measured in microsomal fraction and in homogenates of cat testes. Rat ovaries and piglet testes were used for assay validation. Aromatase activity was not detected in cat testes microsomal fraction (n = 8), not even when the protein amount added to the assay was increased from 50 to 200 μg. In homogenates, however, it was detected (3.5 ± 0.5 pmol.g-1.h-1; n = 7), although in such low levels that no activity inhibition was detectedwhen homogenates were incubated with increasing fadrazole concentrations. Although none of the cats in this study were classified as teratospermic, some sperm defects were correlated with testicular T:E2 ratio (abnormal acrosome, r = -0.76) and with E2 concentration (proximal cytoplasmic droplet, r = 0.77). However, we did not find any correlation between aromatase activity and hormonalor sperm morphology data. To our knowledge this is the first demonstration of testicular aromatase activity in domestic cats. Despite that, due to the low aromatase activity measured and the lack of correlation with other reproductive data, we could not infer that TWRA is a reliable method to detect differences in testicular aromatase activity in normospermic cats. Perhaps this method could be used in teratospermic individuals that probably havean increased aromatase activity. As an alternative, we suggest that more sensitive techniques should be used to compare aromatase activity between normospermic and teratospermic cats.

Testicular testosterone: estradiol ratio in domestic cats and its relationship to spermatogenesis and epididymal sperm morphology.

The phenomenon of teratozoospermia in felids is not fully understood. In this study, we investigated the testicular androgen:estrogen balance in domestic cats and correlated these data with epididymal sperm morphology and the degree of spermatogenic activity. During spring and summer, testes and blood samples were obtained from 37 mixed-breed domestic cats (12 to 48 mo). The epididymal sperm were harvested and evaluated for sperm counts, motility, and morphology. Distal cytoplasmic droplets were not considered a defect, and samples were considered normozoospermic if they contained more than 60% normal sperm (N = 25) or teratozoospermic if they contained less than 45% normal sperm (N = 12). The testicular and serum concentrations of testosterone (T) and 17ß-estradiol (E2) were determined with an enzyme immunoassay. The gonadosomatic index and epididymal sperm numbers and motility did not differ between groups. The percentage of normal sperm was higher in normozoospermic (74.3 ± 2.0, mean ± SEM) than in teratozoospermic samples (43.1 ± 1.4). The most prevalent sperm defects in the teratozoospermic group were abnormal acrosomes (9.7 ± 2.0) and bent midpieces (12.2 ± 2.0) or tails (24.0 ± 2.7) with cytoplasmic droplets. Histomorphometric data were similar between groups, although there was a lower Leydig cell nuclear volume in teratozoospermic samples. Normozoospermic samples contained a higher percentage of haploid cells and had a higher index of total spermatogenic transformation than teratozoospermic samples. Serum concentrations of T (0.5 ± 0.1 vs. 0.8 ± 0.4 ng/mL) and E2 (9.5 ± 1.2 vs. 11.4 ± 2.3 pg/mL) and testicular T concentrations (471.6 ± 65.3 vs. 313.4 ± 57.6 ng/g) were similar between groups. However, compared with normozoospermic samples, teratozoospermic samples had higher testicular E2 concentrations (8.5 ± 3.6 vs. 5.4 ± 0.5 ng/g) and a lower T:E2 ratio (31.8 ± 4.1 vs. 87.2 ± 11.6). There were significant correlations between testicular E2 values and percentages of normal sperm (r = -0.55) as well as those with primary sperm defects (r = 0.58) or abnormal acrosomes (r = 0.64). The T:E2 ratio was also correlated with meiotic index (r = 0.45) and percentage of normal sperm (r = 0.58). In conclusion, a high testicular E2 concentration and a reduced T:E2 ratio were significantly associated with higher ratios of abnormal sperm types, suggesting that the balance between androgens and estrogens is an important endocrine component in the genesis of teratozoospermia in felids.