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.

Seasonal aspects of reproductive physiology in captive male maned wolves (Chrysocyon brachyurus, Illiger 1815).

The aim of the study was to evaluate the seasonality of andrological characteristics and hormonal profile of captive maned wolves (Chrysocyon brachyurus, Illiger 1811). Three adult males were evaluated from the Companhia Brasileira de Metalurgia e Mineração Scientific Breeding Center in Araxá, MG, Brazil, over 13 months. Semen was collected 2-3 times weekly and analysed. Scrotal circumference, biometrics and testicular volume were measured. Stool samples were collected 2-3 times weekly to analyse corticosteroid and testosterone metabolite concentrations. A success rate of 100% was achieved in the collection attempts during the breeding season (BS) and 77.8% during the non-breeding season (NBS). The interval to achieve penile erection was 1-5 min in the BS and 6-10 in the NBS (p < 0.001). Of the ejaculates collected, 80.0% contained sperm during BS, while 28.6% did during the NBS. The ejaculate had only one fraction, was odourless, predominantly translucent (72.4%), with a watery appearance, pH 6.7 and osmolarity of 352.8 mOsmol. Seasonal influences were seen in ejaculate volume (1.3 ml vs 0.4 ml), number of spermatozoa per ejaculate (73.9 × 10(6) vs 6.1 × 10(6) ) and percentage of live sperm (82.0% vs 66.1%) between the BS and NBS (p < 0.05), respectively. A high percentage of major sperm defects were observed in both seasons (50.1% in BS; 65.7% in NBS). Testicular volume was larger (p < 0.05; right testicles 13.1 cm(3) in BS vs 4.0 cm(3) in NBS, while left testicles 12.9 cm(3) in BS vs 5.3 cm(3) in NBS) and testicular consistency increased in the BS. No difference was seen in the basal faecal metabolite concentrations of testosterone; however, the corticosteroid concentrations were higher in the BS. Based on these results, it is possible to conclude that the collection of semen is feasible in captive maned wolves without compromising libido, seminal characteristics and reproductive behaviour and that sperm production is influenced by seasonality; however, it appears that there is no seasonal influence on basal testosterone concentrations.

Influence of cooling rate on the ability of frozen-thawed sperm to bind to heterologous zona pellucida, as assessed by competitive in vitro binding assays in the ocelot (Leopardus pardalis) and tigrina (Leopardus tigrinus).

We evaluated the influence of two cooling rates (from 25 to 5 degrees C) on post-thaw function of frozen sperm in ocelots (Leopardus pardalis; n=3 males) and tigrinas (Leopardus tigrinus; n=4 males). Seven normospermic (>70% normal sperm) electroejaculates from each species were diluted with a 4% glycerol freezing medium, divided into two aliquots, and assigned to one of two cooling rates: fast or slow (0.7 or 0.16 degrees C/min, respectively). Sperm motility index (SMI) and percentage of sperm with an intact acrosome were assessed before freezing and after thawing, and the ability of sperm to bind to the zona pellucida of IVM domestic cat oocytes were assessed in a competitive in vitro sperm-binding assay. Regardless of the cooling rate, frozen-thawed sperm from both species exhibited a SMI of 50; approximately 20 and approximately 32% of post-thaw sperm had an intact acrosome in ocelots and tigrinas, respectively (P<0.05). The mean (+/-S.E.M.) number of sperm bound per oocyte was higher for fast-cooled (8.5+/-1.3) than slow-cooled (2.5+/-0.3; P<0.01) ocelot sperm. In contrast, more tigrina sperm bound to domestic cat oocytes when cooled slowly versus quickly (5.8+/-0.9 versus 2.7+/-0.4, P<0.05). In conclusion, cryopreservation decreased sperm function in both species, and the oocyte-binding assay was the most efficient method to detect functional differences in post-thaw sperm.