Aquaporins (AQPs) are expressed in the uterus, playing a physiological role during pregnancy. An osmotic pathway—through AQP5—may modify the transient potential vanilloid 4 (TRPV4) function and uterine contraction. Our aim was to determine the role of TRPV4 antagonist citral in the regulation of pregnant uterine contraction. In vitro uterine contractions were evoked by KCl and the response was modified with citral. The expressions of TRPV4 and AQP5 were measured by RT-PCR and Western blot techniques. The lengths of gestational periods were determined in normal and LPS-induced preterm births after citral treatment, in vivo. Citral significantly decreased the uterine contraction on day 22 of pregnancy. AQP5 expression significantly increased after citral incubation; however, TRPV4 expression did not show significant changes. After citral pretreatment, the gestational period was extended both in normal and LPS-induced preterm births. Our results suppose that the downregulation of AQP5 may initiate hypertonic stress, activating TRPV4 the uterine contraction on the last day of the gestational period. The putative cooperation between AQP5 and TRPV4 may open a novel target to treat or prevent preterm birth.

Objectives: Obesity and the associated metabolic dysfunction influence fertility performance at molecular levels and ABC transporters are considered as potential molecular factors affecting fertility both in the testis and sperm; therefore, we aimed to examine the effect of a short-term diet-induced obesity on testicular and spermatic ABC transporters in a rat model focusing on the expressions of P-glycoprotein (P-gp, Abcb1) and breast cancer resistance protein (BCRP, Abcg2). The testicular androgen state involving aromatase enzyme (Cyp19a1), androgen receptor (Ar), and testosterone levels were also evaluated. Methods: Obesity was induced in male Sprague Dawley rats by feeding a high-fat, high-sugar diet (HFHSD) for 10 weeks, and metabolic status was evaluated using a glucose tolerance test. The weight and size of reproductive organs were measured, and Abcb1a/1b, Abcg2, Cyp19a1, and Ar expression in testes or sperm was determined by RT-PCR and Western blotting. At the same time, testosterone levels were measured by ELISA. Results: HFHSD successfully induced higher weight gain with glucose intolerance and reduced reproductive organ size. In obese rats, testicular Abcb1a and Abcb1b mRNA and P-gp protein expression were significantly higher, whereas testicular Abcg2 mRNA levels decreased. Spermatic Abcb1a, Abcb1b and Abcg2 mRNA expression also reduced in obesity. Neither testicular testosterone concentration nor Cyp19a1 and Ar mRNA expression levels changed after the 10-week obesogenic diet compared with controls. Conclusions: Overall, our study revealed infertility-related ABC transporter changes in obese male rats, suggesting that these alterations may predispose obese males to fertility impairments, even before the obesity-induced androgen dysregulation.

Background: Calonysterone (CAL) is a natural derivative of 20-hydroxyecdysone (20E) with enhanced bioactivity on skeletal muscle cells in vitro, but its in vivo physiological actions remain less well characterized. This study aimed to compare the effects of 20E and CAL on metabolic, muscular, and endocrine parameters in normal and obese male rats, with a particular focus on androgen balance. Methods: Male rats were treated with 20E or CAL under normal (ND) or high-fat, high-sugar dietary (HFHSD) conditions for 12 weeks. Body weight, food intake, skeletal and androgen-sensitive muscle mass, and testicular weight were measured. Testicular expression of androgen receptor (Ar) and aromatase (Cyp19a1) mRNA was assessed by RT-PCR. ELISA was used to determine the plasma corticosterone, testosterone and ERβ level in testes. Results: 20E and CAL prevented HFHSD-induced weight gain and skeletal muscle atrophy. CAL uniquely preserved testicular and levator ani muscle mass in obese rats. CAL increased the expression of Cyp19a1 and ERβ in testicles. Decreased Ar mRNA expression was regulated in 20E- and CAL-treated obese animals. While 20E treatment significantly reduced plasma testosterone levels in the normal diet group compared to controls, both 20E and CAL interventions elicited significant reductions in the obese group relative to both the ND and HFHSD groups. HFHSD-induced increase in plasma corticosterone levels was normalized by 20E or CAL treatment. Conclusions: 20E and CAL exhibit beneficial metabolic and anabolic effects by preventing HFHSD-induced obesity and consequential muscle atrophy. CAL counteracts obesity-induced testicular atrophy in terms of tissue mass. Based on our results, we hypothesized that CAL enhances testicular aromatase levels, which may lead to increased compensatory androgen receptor mRNA expression and increased ERβ levels. These complex, not yet fully understood results underscore the need for caution in the use of phytoecdysteroids as dietary supplements.