title: Effect of melatonin implants on spermatogenesis in the domestic cat (Felis silvestris catus).
abstract: The aim of this study was to assess the efficacy of subcutaneous melatonin implants to temporarily and reversibly suppress spermatogenesis in male cats. Tomcats (n = 8) were housed in a conditioned room with alternating long and short 2-month photoperiod cycles to maintain sperm production and quality. Animals were randomly assigned to one of the two treatments. Four animals received a subcutaneous melatonin implant (MEL, 18 mg; Syntex, Argentina), whereas the other four received a subcutaneous placebo implant (PLA, 0 mg; Syntex). Semen samples were collected by electroejaculation every 14 days for 252 days. Sperm parameters were evaluated in all ejaculates, and data were analyzed by ANOVA. Melatonin-implanted cats significantly decreased their sperm quality in all the parameters studied compared with the control group (MEL vs. PLA; least squares means ± SEM; motility, 71.3 ± 3.4 vs. 82.1 ± 3.6; velocity, 3.4 ± 0.1 vs. 4.6 ± 0.1; total sperm count, 2.6 ± 2.2 vs. 19.4 ± 3.3; acrosome integrity, 48.7 ± 5.6 vs. 62.8 ± 5.6; plasma membrane integrity, 52.2 ± 4.7 vs. 72.9 ± 5.5; normal sperm morphology, 45.8 ± 3.3 vs. 63.7 ± 3.4; P < 0.05). Conversely, volume and serum testosterone concentrations were similar in both groups (volume, 0.15 ± 0.02; serum testosterone concentrations, 1.1 ± 0.1; CV 18.9%; P > 0.05). At 91 ± 7 days after implant insertion, sperm motility decreased 38.5%, velocity 26.5%, total sperm count 82%, acrosome integrity 22%, plasma membrane integrity 30%, and normal sperm morphology decreased 32% of preimplant values. This effect was present until 120 ± 15 days after implant insertion. After that, seminal parameters started to increase and reached preimplant values at about 140 ± 7 days after implant insertion. Nevertheless, treated animals conserved the capacity to produce semen during the treatment period. In conclusion, a single subcutaneous melatonin implant effectively and reversibly reduced sperm production and quality in male domestic cats for approximately 120 ± 15 days without clinically detectable adverse effects.
authors.affiliation: Universidad Nacional de La Plata, La Plata, Argentina; CONICET, Capital Federal, Argentina.
authors.forename: R Nuñez
authors.initials: RN
authors.lastname: Favre
authors.affiliation: Universidad Nacional de La Plata, La Plata, Argentina; CONICET, Capital Federal, Argentina.
authors.forename: M C
authors.initials: MC
authors.lastname: Bonaura
authors.affiliation: Universidad Nacional de La Plata, La Plata, Argentina; CONICET, Capital Federal, Argentina.
authors.forename: R
authors.initials: R
authors.lastname: Praderio
authors.affiliation: Universidad Nacional de La Plata, La Plata, Argentina.
authors.forename: M C
authors.initials: MC
authors.lastname: Stornelli
authors.affiliation: Universidad Nacional de La Plata, La Plata, Argentina; CONICET, Capital Federal, Argentina.
authors.forename: R L
authors.initials: RL
authors.lastname: de la Sota
authors.affiliation: Universidad Nacional de La Plata, La Plata, Argentina. Electronic address: astornel@fcv.unlp.edu.ar.
authors.forename: M A
authors.initials: MA
authors.lastname: Stornelli
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000008:administration & dosage / Q000494:pharmacology*; D002415:Cats / Q000502:physiology*; D004343:Drug Implants / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male; D008550:Melatonin / Q000008:administration & dosage / Q000494:pharmacology*; D013091:Spermatogenesis / Q000187:drug effects*
chemical_list: D000975:Antioxidants; D004343:Drug Implants; D008550:Melatonin
keywords: Melatonin implants; Sperm production; Tomcats