Effect of natural photoperiod on epididymal sperm quality and testosterone serum concentration in domestic cat (Felis silvestris catus).

The aim of this study was to assess epididymal sperm characteristics and serum testosterone concentration in cats under natural photoperiod. The hypothesis was that natural photoperiod induces seasonal changes in spermatozoal quality and serum testosterone concentration. Mixed breed tomcats (n = 43) that underwent bilateral orchiectomy at a municipal public pet shelter were used in the study. Epididymides were divided into two groups according to time of castration. In Group I, toms were castrated during increasing light (IL; [winter and spring; n = 24]), and group II, during decreasing light (DL; [summer and fall; n = 19]). Only mature toms castrated in the two lasts weeks of each season were included in this study. Sperm samples were obtained by cutting the cauda epididymis in Tris solution and tested for motility (MOT,% motile), velocity (VEL, 0-5), total sperm cells (TS, 10(6) ), acrosome integrity (ACR,% intact; FITC-PSA), plasma membrane integrity (MI,%intact; CFDA-PI) and sperm morphology (SM,% normal). Before orchiectomy, blood samples were taken to measure serum concentrations of testosterone (T2) by a solid-phase RIA. Data were analysed with the mixed procedure of SAS. Toms castrated during IL had higher sperm plasma membrane integrity and better sperm morphology compared to toms castrated during DL (69.0 ± 2.7 vs 60.6 ± 2.1, p < 0.01; 45.9 ± 2.5 vs 35.9 ± 3.4; p < 0.02; respectively) and tended to have higher sperm motility and total number of sperm cells compared to toms castrated during DL (56.3 ± 2.8 vs 47.3 ± 3.7, p < 0.06; 13.8 ± 1.4 vs 10.0 ± 1.8, p < 0.09). However, velocity, acrosome integrity and serum testosterone concentrations were similar between both groups (3.5 ± 0.1 vs 3.4 ± 0.1, p > 0.6; 45.8 ± 3.3 vs 44.0 ± 4.0, p > 0.72; 0.76 ± 0.15 vs 0.59 ± 0.19, p > 0.51; respectively). In conclusion, natural photoperiod induces seasonal changes in sperm quality with a moderate variation in serum testosterone concentrations.

Effect of refractoriness to long photoperiod on sperm production and quality in tomcats.

The aim of this study was to assess whether refractoriness to long photoperiod (LP) could be reversed by subjecting tomcats to a period of short days. Our hypothesis was that photoperiod changes can avoid refractoriness and restore sperm quality and production to that before refractoriness. Tomcats (n = 6) were housed in a conditioned room with LP (12L: 12D) for 45 days of acclimation and then maintained under LP for 18 month. Then, tomcats were changed to a period of decreasing light at a rate of 8 min/day for 1 month. Tomcats stayed for 1 month with short photoperiod (SP; 8L: 16D) and then were switched back to a period of increasing light at a rate of 8 min/day for 1 month. The experiment was completed after tomcats remained in LP for 2 months. Toms were anaesthetized and semen samples were collected by electroejaculation every 2 weeks. Sperm parameters were evaluated in all ejaculates, and data were analysed by anova. Motility, velocity, volume, sperm concentration, total sperm count, viability, acrosome integrity, plasma membrane integrity and sperm morphology were higher during LP compared with a refractory LP (p < 0.01). Likewise, velocity, viability, acrosome integrity, plasma membrane integrity and sperm morphology were higher in a LP compared with a SP (p < 0.05). On the other hand, motility, volume, concentration and total sperm count were similar between LP and SP (p > 0.20).Whereas motility, velocity, viability, acrosome integrity and plasma membrane integrity were similar in a refractory LP compared with SP (p > 0.05), volume, sperm concentration, total sperm count and sperm morphology were lower in a refractory LP compared with SP (p < 0.05). In conclusion, refractoriness and reduced sperm production and quality induced by a prolonged LP of 18 month can be restored after placing tomcats to a SP.

Effect of storage media and storage time on histological and ultrastructural changes in cat epididymal cells.

The aim of this study was to assess the histological and ultrastructural changes in cat epididymides (n = 22) stored at 4 °C in two different media [saline solution (SAL) or tris-egg yolk (TEY)]. Our hypothesis was that epididymides stored in TEY would have delayed epithelial cell autolysis. Four epididymides were fixed and processed immediately, and the remaining 18 epididymides were stored at 4 °C in SAL or TEY for 24, 48 or 72 h. In histological sections, the nuclear features and stereocilia morphology were scored from 0 to 3. Ultrastructurally, nuclear chromatin and stereocilia morphology were scored from 0 to 3. In addition, using transmission electron microscopy nuclear number, nuclear area, mitochondrial number and mitochondrial area were recorded. In the histological study, parameters changed with time and media (p < 0.01). A significant effect of time was observed (p < 0.01), and the morphological changes were greatest when the storage time increased. Morphological changes were higher in SAL compared with TEY (p < 0.01). In the ultrastructural study, nuclear chromatin and stereocilia morphology decreased with time and media as in the histological study (p < 0.01). In addition, nuclear number and nuclear area changed with time (p < 0.004; p < 0.001) but not with media. Conversely, mitochondrial number and mitochondrial area did not change with media or time (p > 0.05). In conclusion, these results show that TEY preserved epididymal epithelial cells better than SAL; this finding could help improve sperm quality of stored epididymides.

Seasonal changes in testicular cell morphology in domestic male cats (Felis catus).

The aim of this study was to asses the variation in the morphology of the seminal epithelium in relation to natural photoperiod in male cats. Tom cats (n = 240) were castrated every other week throughout the year. Each testis was fixed in Bouin's solution and cut into sections. The percentage of tubules with round spermatids (RS), elongated spermatids (ES), tailed spermatids (TS), mature spermatids (MS) and the number of Sertoli cells (SC) and Leydig cells (LC) were recorded in each sample. Testicles from males during short days (SHD) had a higher percentage of tubules with RS and ES compared to testicles from males during long days (LHD, 31.3 +/- 0.6 vs 2.1 +/- 0.6%, p < 0.001; 30.9 +/- 0.7 vs 11.0 +/- 0.7%, p < 0.001). Conversely, testicles from males during SHD had a lower percentage of tubules with TS and MS compared to testicles from males during LHD (24.5 +/- 0.8 vs 29.7 +/- 0.8%, p < 0.01; 13.1 +/- 1.2 vs 57.0 +/- 1.2%, p < 0.01). Furthermore, testicles from males during SHD had a higher number of SC and lower number of LC compared to testicles from males during LHD (11.4 +/- 0.1 vs 8.0 +/- 0.1%, p < 0.01; 19.2 +/- 1.0 vs 38.0 +/- 1.0%, p < 0.01). In conclusion, there are seasonal changes in testis cell morphology in the tom which may be related to seasonal sperm production.

Suppression of estrus in cats with melatonin implants.

The objective of this study was to assess the efficacy of a subcutaneous melatonin implant to suppress estrus in queens (felis catus). The hypothesis was that this implant would temporarily and reversibly suppress estrus in queens without producing any clinically detectable side effects. Fourteen adult queens were maintained in cages under artificial illumination (14h light:10h dark) for 45 d and then randomly assigned to one of two treatments. At interestrus, queens received a single subcutaneous melatonin implant (18mg; Melovine [CEVA Sante Animal, Libourne, France]; MEL: n=9), or a single subcutaneous placebo implant without melatonin (0mg; PLA; n=5). At the next estrus, all queens received a second MEL (n=9) or PLA (n=5) implant. Blood samples were taken when queens displayed estrous signs and during interestrus to measure estradiol (E(2)) and progesterone (P(4)), respectively, by radioimmunoassay. There were no significant differences in duration of the interestrus interval in PLA cats, regardless of whether the implants were placed during interestrus or estrus (6.0+/-9.7 d vs. 6.0+/-9.7 d, respectively; least square means [LSM]+/-SEM). However, when MEL implants were placed during interestrus, the duration of interestrus was approximately twice as long as that occurring when MEL implants were placed during estrus (113.3+/-6.1 d vs. 61.1+/-6.8 d, respectively; P<0.01). Serum E(2) and P(4) concentrations were similar in queens with PLA and MEL implants and in queens that received implants in estrus and interestrus. In conclusion, a subcutaneous MEL implant effectively and reversibly suppressed estrus in queens for approximately 2 to 4 mo with no clinically detectable side effects.