Effect of two artificial photoperiods on male domestic cat reproduction

A thorough understanding of the effect of exogenous light could offer a natural method for reproduction manipulation in the domestic cat. The aim of this study was to describe and compare the effect of a long (LP) and a short (SP) artificial photoperiod on testicular, hormonal and seminal parameters. Male cats were housed in windowless rooms and exposed to a SP (6:18 L/D; n = 4) or a LP (16:8 L/D; n = 4) for three months. Blood and semen samples were collected at the end of the third month before castrations. Testes were gross, histologically and immunohistochemically evaluated. Serum melatonin was higher in the SP than in LP (989.03 ± 70.58 vs. 800.91 ± 93.80 pg/ml, respectively; P < 0.05). Neither anti-mullerian hormone (AMH; 5.81 ± 1.80 vs. 6.14 ± 0.78 ng/ml, respectively; P > 0.05) nor testosterone (5.41 ± 2.45 vs. 3.74 ± 2.11 ng/ml, respectively; P > 0.1) differed between SP and LP. There was no correlation between melatonin and other hormones while testosterone and AMH were negatively correlated (r = - 0.94; P < 0.01). Sperm abnormalities were lower in LP than in the SP (P < 0.05). Seminiferous tubular diameter (P < 0.1) and tubular epithelium height (P < 0.05) were larger in LP than in SP. Elongated spermatids (P < 0.05), spermatozoa (P < 0.01) as well as the meiotic index (P < 0.05) and Leydig cells (P < 0.01) increased in LP. There was a tendency to a higher percentage of PCNA-positive germ cells in the LP (P < 0.1). Caspase-3 positive percentage was higher in SP in both the nucleus (P < 0.05) and cytoplasm (P < 0.05). No differences in vimentin immunoreactivity were found between groups.