Promoting Effect of L-tyrosine Supplement on New Zealand Rabbit Bucks' Performance and Reproduction Through Upregulation of Steroidogenic Markers

Folliculogenesis and steroidogenesis alterations after chronic exposure to a human-relevant mixture of environmental toxicants spare the ovarian reserve in the rabbit model

BACKGROUND

Industrial progress has led to the omnipresence of chemicals in the environment of the general population, including reproductive-aged and pregnant women. The reproductive function of females is a well-known target of endocrine-disrupting chemicals. This function holds biological processes that are decisive for the fertility of women themselves and for the health of future generations. However, insufficient research has evaluated the risk of combined mixtures on this function. This study aimed to assess the direct impacts of a realistic exposure to eight combined environmental toxicants on the critical process of folliculogenesis.

METHODS

Female rabbits were exposed daily and orally to either a mixture of eight environmental toxicants (F group) or the solvent mixture (NE group, control) from 2 to 19 weeks of age. The doses were computed from previous toxicokinetic data to reproduce steady-state serum concentrations in rabbits in the range of those encountered in pregnant women. Ovarian function was evaluated through macroscopic and histological analysis of the ovaries, serum hormonal assays and analysis of the expression of steroidogenic enzymes. Cellular dynamics in the ovary were further investigated with Ki67 staining and TUNEL assays.

RESULTS

F rabbits grew similarly as NE rabbits but exhibited higher total and high-density lipoprotein (HDL) cholesterol levels in adulthood. They also presented a significantly elevated serum testosterone concentrations, while estradiol, progesterone, AMH and DHEA levels remained unaffected. The measurement of gonadotropins, androstenedione, pregnenolone and estrone levels yielded values below the limit of quantification. Among the 7 steroidogenic enzymes tested, an isolated higher expression of Cyp19a1 was measured in F rabbits ovaries. Those ovaries presented a significantly greater density/number of antral and atretic follicles and larger antral follicles without any changes in cellular proliferation or DNA fragmentation. No difference was found regarding the count of other follicle stages notably the primordial stage, the corpora lutea or AMH serum levels.

CONCLUSION

Folliculogenesis and steroidogenesis seem to be subtly altered by exposure to a human-like mixture of environmental toxicants. The antral follicle growth appears promoted by the mixture of chemicals both in their number and size, potentially explaining the increase in atretic antral follicles. Reassuringly, the ovarian reserve estimated through primordial follicles number/density and AMH is spared from any alteration. The consequences of these changes on fertility and progeny health have yet to be investigated.

Ameliorative Effects of Boswellic Acid on Fipronil-Induced Toxicity: Antioxidant State, Apoptotic Markers, and Testicular Steroidogenic Expression in Male Rats

The study investigated the ability of boswellic acid (BA) to alleviate the testicular and oxidative injury FPN insecticide intoxication in the male rat model. Rats were randomly assigned to six equivalent groups (six rats each) as the following: control rats orally administered with 2 mL physiological saline/kg of body weight (bwt); boswellic acid (BA1) rats orally administered 250 mg BA/kg bwt; boswellic acid (BA2) rats orally administered 500 mg BA/kg bwt; fipronil (FPN) rats orally administered 20 mg FPN/kg bwt; (FPN + BA1) rats orally administered 20 mg FPN/kg bwt plus 250 mg BA/kg bwt, and (FPN + BA2) rats orally administered 20 mg FPN/kg bwt plus 500 mg BA/kg bwt. After 60 days, semen viability percentage and live spermatozoa percentage were decreased, and a considerably increased abnormality of the sperm cells in FPN-administered rats improved substantially with the co-administration of BA. BA had refinement of the histological architecture of testes and sexual glands. Quantitative analysis recorded a noticeable decline in the nuclear cell-proliferating antigen (PCNA) percentage area. FPN triggered cell damage, which was suggested by elevated malondialdehyde and interleukin 6, tumor necrosis factors alpha, and decreased glutathione level. Proapoptotic factor overexpression is mediated by FPN administration, while it decreased the antiapoptotic protein expression. Similarly, BA has shown significant upregulation in steroidogenic and fertility-related gene expression concerning the FPN group. Pathophysiological damages induced by FPN could be alleviated by BA's antioxidant ability and antiapoptotic factor alongside the upregulation of steroidogenic and fertility-related genes and regimented the detrimental effects of FPN on antioxidant and pro-inflammatory biomarkers.