A Comparison of Oocyte Yield between Ultrasound-Guided and Laparoscopic Oocyte Retrieval in Rhesus Macaques.

Obtaining quality oocytes is a prerequisite for ART-based studies. Here we describe a method for transabdominal ultrasound-guided (US) oocyte retrieval in rhesus macaques (Macaca mullata) and compare it to the standard surgical approach using laparoscopy (LAP). We analyzed oocyte yield from six continuous reproductive seasons (2017-2023) that included n = 177 US-guided and n = 136 laparoscopic oocyte retrievals. While the ultrasound-guided technique retrieved significantly fewer oocytes on average (LAP: 40 ± 2 vs. US: 27 ± 1), there was no difference in the number of mature metaphase II oocytes (MII) between the two techniques (LAP: 17 ± 1 vs. US: 15 ± 1). We show that oocytes retrieved by the ultrasound-guided approach fertilize at the same rates as those obtained via the laparoscopic procedure (LAP Fert Rate: 84% ± 2% vs. US Fert Rate: 83% ± 2%). In conclusion, minimally invasive ultrasound-guided oocyte retrieval improves animal welfare while delivering equivalent numbers of mature oocytes, which are ideal for ART. Furthermore, we show that oocyte competency, as represented by fertilization rate, is not affected by retrieval technique. Therefore, the Oregon National Primate Research Center (ONPRC) has adopted the ultrasound-guided approach as the standard technique for oocyte retrieval.

Cessation of chronic delta-9-tetrahydrocannabinol use partially reverses impacts on male fertility and the sperm epigenome in rhesus macaques.

OBJECTIVE: To determine whether discontinuation of delta-9-tetrahydrocannabinol (THC) use mitigates THC-associated changes in male reproductive health using a rhesus macaque model of daily THC edible consumption. DESIGN: Research animal study. SETTING: Research institute environment. PATIENT(S): Adult male rhesus macaques (age, 8-10 years; n = 6). INTERVENTION(S): Chronic daily THC edible administration at medically and recreationally relevant contemporary doses followed by cessation of THC use. MAIN OUTCOME MEASURE(S): Testicular volume, serum male hormones, semen parameters, sperm deoxyribonucleic acid (DNA) fragmentation, seminal fluid proteomics, and whole genome bisulfite sequencing of sperm DNA. RESULT(S): Chronic THC use resulted in significant testicular atrophy, increased gonadotropin levels, decreased serum sex steroid levels, changes in seminal fluid proteome, and increased DNA fragmentation with partial recovery after discontinuation of THC use. For every increase of 1 mg/7 kg/day in THC dosing, there was a significant decrease in the total testicular volume bilaterally by 12.6 cm3 (95% confidence interval [CI], 10.6-14.5), resulting in a 59% decrease in volume. With THC abstinence, the total testicular volume increased to 73% of its original volume. Similarly, with THC exposure, there were significant decreases in the mean total testosterone and estradiol levels and a significant increase in the follicle-stimulating hormone level. With increasing THC dose, there was a significant decrease in the liquid semen ejaculate volume and weight of coagulum; however, no other significant changes in the other semen parameters were noted. After discontinuing THC use, there was a significant increase in the total serum testosterone level by 1.3 ng/mL (95% CI, 0.1-2.4) and estradiol level by 2.9 pg/mL (95% CI, 0.4-5.4), and the follicle-stimulating hormone level significantly decreased by 0.06 ng/mL (95% CI, 0.01-0.11). Seminal fluid proteome analysis revealed differential expression of proteins enriched for processes related to cellular secretion, immune response, and fibrinolysis. Whole genome bisulfite sequencing identified 23,558 CpGs differentially methylated in heavy-THC vs. pre-THC sperm, with partial restoration of methylation after discontinuation of THC use. Genes associated with altered differentially methylated regions were enriched for those involved in the development and function of the nervous system. CONCLUSION(S): This is the first study demonstrating that discontinuation of chronic THC use in rhesus macaques partially restores adverse impacts to male reproductive health, THC-associated sperm differentially methylated regions in genes important for development, and expression of proteins important for male fertility.

Chronic exposure to delta-9-tetrahydrocannabinol impacts testicular volume and male reproductive health in rhesus macaques.

OBJECTIVE: To determine the dose-dependent effect of delta-9-tetrahydrocannabinol (THC) exposure on male testes and reproductive health in a nonhuman primate model. DESIGN: Research animal study. SETTING: Research institute. ANIMAL(S): Adult male rhesus macaques 8-10 years of age (n = 6). INTERVENTION(S): Daily edible THC at medically and recreationally relevant doses. MAIN OUTCOME MEASURE(S): Testicular volume and epididymal head width, serum levels of inhibin B, albumin, total testosterone, prolactin, follicle-stimulating hormone, estradiol, and luteinizing hormone; semen volume; and sperm motility, morphology, and concentration. RESULT(S): For each 1 mg/7 kg/day increase in THC dosing, there was a marked loss in total bilateral testicular volume of 11.8 cm3 (95% confidence interval [CI]: 8.3-15.4). In total, average bilateral testicular volume decreased by 58%. Significant dose-response decreases in mean total testosterone level by 1.49 ng/mL (95% CI: 0.83-2.15) and in estradiol level by 3.8 pg/mL (95% CI: 2.2-5.4) were observed, but significant increases in the levels of follicle-stimulating hormone by 0.06 ng/mL (95% CI: 0.02-0.10), luteinizing hormone by 0.16 ng/mL (95% CI: 0.08-0.25), and prolactin by 7.4 ng/mL (95% CI: 3.4-11.3) were observed. There were no statistically significant changes in semen parameters. CONCLUSION(S): In rhesus macaques, chronic exposure to THC resulted in significant dose-response testicular atrophy, increased serum gonadotropin levels, and decreased serum sex steroids, suggestive of primary testicular failure. Further studies are needed to determine if reversal of these observed adverse effects would occur if THC was discontinued and for validation of thefindings in a human cohort.

Chronic hyperandrogenemia in the presence and absence of a western-style diet impairs ovarian and uterine structure/function in young adult rhesus monkeys.

STUDY QUESTION: Does chronic hyperandrogenemia beginning at menarche, in the absence and presence of a western-style diet (WSD), alter ovarian and uterine structure-function in young adult rhesus monkeys? SUMMARY ANSWER: Phenotypic alterations in ovarian and uterine structure/function were induced by exogenous testosterone (T), and compounded in the presence of a WSD (T+WSD). WHAT IS KNOWN ALREADY: Hyperandrogenemia is a well-established component of PCOS and is observed in adolescent girls, indicating a potential pubertal onset of disease symptoms. Obesity is often associated with hyperandrogenemia and it is hypothesized that metabolic dysfunction exacerbates PCOS symptoms. STUDY DESIGN, SIZE, DURATION: Macaque females (n = 40) near the onset of menarche (~2.5 years of age) were assigned to a 2 by 2 factorial cohort design. Effects on reproductive characteristics were evaluated after 3 years of treatment. PARTICIPANTS/MATERIALS, SETTING, METHODS: Rhesus macaques (Macaca mulatta) were fed either a normal balanced diet (n = 20) or a WSD (n = 20). Additionally, implants containing cholesterol (n = 20) or T (n = 20) were implanted subcutaneously to elevate serum T approximately 5-fold. This resulted in treatment groups of controls (C), T, WSD and T+WSD (n = 10/group). Vaginal swabbing was performed daily to detect menses. After 3 years of treatment, daily serum samples from one menstrual cycle were assayed for hormone levels. Ovarian structure was evaluated in the early follicular phase by 3D/4D ultrasound. Uterine endometrial size and ovarian/luteal vascular function was also evaluated in subgroups (n = 6/group) in the late follicular and mid-luteal phases by 3D/4D ultrasound and contrast-enhanced ultrasound, respectively. Expression of steroid hormone receptors and markers of decidualization and endometrial receptivity were assessed in endometrial biopsies at mid-luteal phase. MAIN RESULTS AND THE ROLE OF CHANCE: Approximately 90% of menstrual cycles appeared ovulatory with no differences in frequency or duration between groups. Serum estradiol (E2) levels during the early follicular phase were greatest in the T alone group, but reduced in T+WSD (P < 0.02). Serum LH was elevated in the T group (P < 0.04); however, there were no differences among groups in FSH levels (P > 0.13). Ovarian size at menses tended to be greater in the WSD groups (P < 0.07) and antral follicles ≥1 mm were more numerous in the T+WSD group (P < 0.05). Also, females in T and T+WSD groups displayed polycystic ovarian morphology (PCOM) at greater frequency than C or WSD groups (P < 0.01). Progesterone (P4) levels during the luteal phase were reduced in the T+WSD group compared to C and T groups (P < 0.05). Blood volume (BV) and vascular flow (VF) within the corpus luteum was reduced in all treatment groups compared to C (P < 0.01, P = 0.03), with the WSD alone group displaying the slowest BV and VF (P < 0.05). C and WSD groups displayed endometrial glands at mid-luteal phase with low estrogen receptor 1 (ESR1) and progesterone receptor (PGR) mRNA and immunohistochemical staining in the functionalis zone, but appreciable PGR in the stroma. In contrast, T and T+WSD treatment resulted in glands with less secretory morphology, high ESR1 expression in the glandular epithelium and low PGR in the stroma. Endometrial levels of TIMP3 and MMP26 mRNA and immunostaining were also decreased in the T and T+WSD groups, whereas AR expression was unchanged. LARGE SCALE DATA: None. LIMITATIONS, REASONS FOR CAUTION: Females are young adults, so effects could change as they reach prime reproductive age. The T level generated for hyperandrogenemia may be somewhat greater than the 3-4-fold increase observed in adolescent girls, but markedly less than those observed in male monkeys or adolescent boys. WIDER IMPLICATIONS OF THE FINDINGS: Alterations to ovarian and uterine structure-function observed in T and, in particular, T+WSD-treated female macaques are consistent with some of the features observed in women diagnosed with polycystic ovary syndrome (PCOS), and suggest impaired fertility. STUDY FUNDING/COMPETING INTEREST(S): Research reported in this publication was supported by the Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD) of the National Institutes of Health (NIH) under Award Number P50HD071836 (to RLS). The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH. Additional funding was provided by Office of the Director, NIH under Award Number P51OD011092 (Support for National Primate Research Center). Authors declare no competing interests.