The rat prostate comprises dorsal, ventral and lateral lobes that are morphologically and biochemically distinct. Lesions to these structures are expected to affect the quality of the ejaculate and male fertility. In experiment 1, we analyzed ejaculate parameters of males that had chemical lesions of the dorsal or ventral lobes. At pre-lesion and at 5 and 20 days post-lesion males were mated, and after ejaculation, seminal fl uid and seminal plug were obtained from the mated females. In experiment 2, the ventral lobes were ablated, and the ejaculate was analyzed. In experiment 3, the fertility of males with chemically-lesioned dorsal lobes or ablation of the ventral lobes was evaluated. Chemical lesion of the dorsal lobe prevented the adhesion of the seminal plug to vaginal walls. When these males were tested at 5-days postlesion, no sperm were found in uterus, and at 20-days post-lesion, the few sperm encountered showed slow progressive motility. None of the females that mated with dorsal lobe-lesioned males became pregnant. However, chemical lesion or ablation of the ventral lobes did not affect ejaculate or fertility. Our results indicate that the dorsal prostatic lobes are indispensable for reproductive success in males, and defi ne parameters of ejaculate with which fertility can be estimated.
Individual male rats may systematically display or not copulatory behavior when paired with receptive females. Although these phenotypes are associated with differences in brain organization and function, they might also do so at the level of the reproductive organs. We then used high performance liquid chromatography to quantify serotonin concentration and the activity of tryptophan hydroxylase in the reproductive organs of copulator and non-copulator males. Sexual behavior display was compared between groups and parameters of fertility and reproductive fitness were determined for copulator males. Copulator males had higher concentrations of serotonin in the epididymis, testicle and ventral prostate than their non-copulator counterparts, as it was found for epididymal and testicular tryptophan hydroxylase activity. However, preliminary data shows that serotonin elevation occurs in copulator males only until they have accumulated several sexual encounters, so it might be a response to genital gratification or sexual rewarding. Interestingly, only epididymal serotonin concentration correlated with reproductive fitness, offspring number, mating success and seminal plug volume in copulator males. Our results support that copulator and non-copulator male rats feature a phenotype-specific serotoninergic tone in the epididymis, testicle and ventral prostate gland. The observation documenting that epididymal serotonin concentration correlated with parameters that monitor male fertility and reproductive fitness in copulator males predicts that epididymal factors increase their chances of parenting offspring
SUMMARYThe studies of sexual satiety in male rats under the Coolidge effect indicate that males reassume copulation until ejaculation. Recently, it was demonstrated that sexually satiated males preserve the motor patterns of intromission and ejaculation, also penile erection, but not seminal expulsion. The first aim was to investigate if penile erections displayed by sexually satiated males dislodge the seminal plugs from the vagina and its effect on sperm transcervical transport. The second aim was to determine the recovery time of seminal expulsion after sexual satiety and its optimal ability to induce pregnancy. Results show that during the Coolidge effect males were able to dislodge the seminal plugs deposited by others (experiment 1A) disturbing the sperm transport (experiment 1B) then interfering with pregnancy (experiment 1C). After satiation, the ejaculate parameters recover slowly: it starts after 10 days with the seminal plug formation, and continues with an increase in sperm count in the uterus 15 days post-satiety (experiment 2). Sexually satiated males impregnated only 28% of the females during 15 days of cohabitation, whereas, satiated males that rested for 15 days impregnated 89% of the females (experiment 3). We concluded that males with successive ejaculations remain potential rivals, because they may disrupt the sperm transport of other males. The ejaculate features recovery after sexual satiety is gradual, begins with the secretions of the sex accessory glands and is followed by the sperm count. Full fertility recovery is reached after 15 days of sexual abstinence when males are able to impregnate most females.
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