Effect of Chronic Moderate Caloric Restriction on the Reproductive Function in Aged Male Wistar Rats

Effects of Calorie Restriction on Preserving Male Fertility Particularly in a State of Obesity

PURPOSE OF REVIEW

Highlight the importance of exploring nutritional interventions that could be applied as alternative or supplementary therapeutic strategies to enhance men's fertility.

RECENT FINDINGS

Lifestyle choices have prompted extensive discussions regarding its implications and applications as a complementary therapy. The growing concern over the decline in sperm quality underscores the urgency of investigating these alternative interventions. Calorie restriction (CR) has emerged as a promising strategy to improve male fertility. The efficacy of CR depends on factors like age, ethnicity and genetics. Clinical studies, such as CALERIE, have shown an improvement in serum testosterone level and sexual drive in men with or without obesity. Additionally, CR has been shown to positively impact sperm count and motility; however, its effects on sperm morphology and DNA fragmentation remain less clear, and the literature has shown discrepancies, mainly due to the nature of technically dependent assessment tools. The review advocates a personalized approach to CR, considering individual health profiles to maximize its benefits. It underscores the need for routine, accessible diagnostic techniques in male reproductive health. It suggests that future research should focus on personalized dietary interventions to improve male fertility and overall well-being in individuals with or without obesity and unravel CR's immediate and lasting effects on semen parameters in men without obesity.

Paternal starvation affects metabolic gene expression during zebrafish offspring development and lifelong fitness

Dietary restriction in the form of fasting is a putative key to a healthier and longer life, but these benefits may come at a trade-off with reproductive fitness and may affect the following generation(s). The potential inter- and transgenerational effects of long-term fasting and starvation are particularly poorly understood in vertebrates when they originate from the paternal line. We utilised the externally fertilising zebrafish amenable to a split-egg clutch design to explore the male-specific effects of fasting/starvation on fertility and fitness of offspring independently of maternal contribution. Eighteen days of fasting resulted in reduced fertility in exposed males. While average offspring survival was not affected, we detected increased larval growth rate in F1 offspring from starved males and more malformed embryos at 24 h post-fertilisation in F2 offspring produced by F1 offspring from starved males. Comparing the transcriptomes of F1 embryos sired by starved and fed fathers revealed robust and reproducible increased expression of muscle composition genes but lower expression of lipid metabolism and lysosome genes in embryos from starved fathers. A large proportion of these genes showed enrichment in the yolk syncytial layer suggesting gene regulatory responses associated with metabolism of nutrients through paternal effects on extra-embryonic tissues which are loaded with maternal factors. We compared the embryo transcriptomes to published adult transcriptome datasets and found comparable repressive effects of starvation on metabolism-associated genes. These similarities suggest a physiologically relevant, directed and potentially adaptive response transmitted by the father, independently from the offspring's nutritional state, which was defined by the mother.

The impact of subchronic hypercaloric and restriction diets on sexual behavior, serum testosterone, and prostate histology in rats

The role of diet in health is crucial, with calorie intake playing a significant role. Hypercaloric diets (HD) often lead to adipose tissue accumulation and increased risk of chronic diseases, including reproductive impairments. By contrast, restriction diets (RD) help with weight loss, improve cardiovascular function, and ameliorate reproduction. Herein we sought to investigate the impact of subchronic HD and RD on body weight, sexual behavior, serum testosterone and prostate histology in rats. Hence, 10-week old male rats gained sexual experience during five trials with ovariectomized, hormone-primed females. Then at postnatal week PW15 the males were organized in three groups, depending on the feeding they received until PW18: HD, RD and standard diet (SD). During PW19-22 they were tested for sexual behavior, and at PW23 were euthanized for prostate histology (hematoxylin & eosin stain) and hormone analysis. Results indicated that HD males increased their body weight (16-23%) compared to SD and RD. Furthermore, HD males showed 65% less testosterone than RD males. The prostate of HD males revealed histological alterations, including a notable increase in epithelium height and other abnormal features, while no changes were observed in the performance of sexual behavior between HD and RD, although HD appeared to facilitate ejaculation when compared to SD. The histological features of RD males were comparable to SD males. Accordingly, we argue that subchronic modifications in calorie intake can alter body weight (in HD), serum testosterone levels (HD and RD in opposite directions), and prostate histology (in HD), while having no immediate effect on male sexual behavior.

Diet and Fertility Status: Relevance in Health and Disease

The prevalence of obesity and other metabolic disorders is increasing worldwide [...].