Primate research was well represented by 24 students and their mentors at the 25th UW–Madison Undergraduate Research Symposium on April 28, 2023. Their abstracts follow.
ROLE OF HYPOTHALAMIC ESTROGEN RECEPTOR ALPHA KNOCKDOWN ON NEUROPEPTIDE S AND BLOOD HORMONE LEVELS IN ASSOCIATION WITH ENDOMETRIOSIS DEVELOPMENT IN ADULT FEMALE RHESUS MONKEYS
Lauren Allegretti, Alexandra Ho. Mentors: David Abbott, Dan Uhlrich
Endometriosis is an extremely detrimental estrogen-dependent condition of the pelvic organs in which endometrial tis- sue develops outside of the uterus. Current treatment options are not curative and can be invasive. Recent investigations have found a link between a gene variant coding for Neuropeptide S Receptor 1 (NPSR1), over-expression of NPSR1 and endometriosis. Another study found blocking estrogen activity in the hypothalamus using estrogen receptor alpha (ERa) knockdown in adult female rhesus monkeys provokes a high rate of endometriosis when compared to control monkeys. In previous years, students found expression of NPS in the monkey hypothalamus. This investigation quantifies NPS and will provide a greater understanding concerning the association of endometriosis with NPSR1 overexpression.
NATURALLY OCCURRING HIGH TESTOSTERONE IN PREPUBESCENT NONHUMAN FEMALE RHESUS MACAQUES OFFERS INSIGHT INTO ORIGINS OF POLYCYSTIC OVARY SYNDROME
Natalia Badillo, Anna Just. Mentor: David Abbott
Polycystic Ovary Syndrome (PCOS) affects 18% of women of reproductive age worldwide. The leading cause of female reproductive and metabolic dysfunction, PCOS and its accompanying morbidities go underdiagnosed despite its high prevalence. Similar to humans, female rhesus macaques give insights into the origins and pathogenesis of PCOS as they similarly naturally exhibit high testosterone (T) levels, a symptom of PCOS. The examination of T levels and PCOS symp- toms of female rhesus macaques allows for insights into the origins of PCOS in women and how PCOS may arise during prepubescent and adolescent ages. Increased clitoral volume in 2 of 3 high T female rhesus macaques indicated exposure to high T before menarche and drives hypotheses surrounding heritability of PCOS from mother to child.
OVARIAN FOLLICLE POPULATION IN ADULT FEMALE RHESUS MACAQUES WITH NATURALLY OCCURRING HIGH TESTOSTERONE
Danielle Bellino. Mentor: David Abbott
In a pedigree of adult female rhesus macaques, we have identified those that have naturally occurring high testosterone levels (>0.31 ng/mL), similar to women with polycystic ovary syndrome (PCOS), and normal testosterone levels (<0.31 ng/mL). To gain insights into the impact of testosterone on ovarian follicular development, we quantified the ovarian fol- licle population in adult female rhesus macaques with naturally occurring high testosterone (n=4) and normal testosterone (n=4) that were pair matched in terms of age and weight. We hypothesized that there will be a greater proportion of grow- ing follicles, indicative of polycystic ovaries, in the rhesus macaques with naturally occurring high testosterone compared to those with normal testosterone.
THE EFFECTS OF A NOVEL GUM FEEDER ON THE BEHAVIOR OF CAPTIVE COMMON MARMOSETS
Ethan Bernt, Lucine Yen. Mentor: Peter Pierre
Environmental enrichment is implemented to promote species-typical behavior and welfare in captive non-human primates. In this study, we will observe the interactions of pair-housed common marmosets (n=20) with a wooden “gum feeder” that delivers gum, a diet staple for common marmosets, in a similar manner to natural sources. Using an ethogram, we will measure the frequency and duration of foraging and other interactive behaviors. We hypothesize that, by providing gum in a method more akin to naturally occuring plant exudates, we will see an increase in species-typical behaviors and a decrease in stereotypical and agonistic behaviors. With these results, we can refine how we deliver enrichment opportunities to this species in a manner that invites interaction and sustains engagement.
EFFECTS OF CIRCULATING ESTRADIOL LEVELS ON UTERINE ENDOMETRIAL DEPTH IN MONKEYS
Jacob Blanchar. Mentor: David Abbott
Optimal uterine endometrial depth (UED) is essential for female reproductive health. We quantified UED employing digital calipers on images obtained from trans-abdominal ultrasonography of female rhesus monkeys. Monkey groups (1) were depleted of ovarian estradiol (VEH), (2) were deleted of ovarian and extra-ovarian estradiol, or (3) had ovarian estradiol maintained (E2). Since UED is responsive to changes in circulating estradiol levels, we hypothesized the following UED values for each treatment group: E2>VEH>LET. If these results are found, it would be the first time extra- ovarian estradiol has been shown to regulate UED. Extra-ovarian estradiol may thus play an unsuspected role in maintaining optimal UED.
THE EFFECTS OF DECREASED ESTRADIOL ACTION IN METABOLIC REGULATION OF WHITE AND BROWN ADIOCYTE LIPOLYSIS AND THERMOGENESIS IN FEMALE NONHUMAN PRIMATES
Benjamin Bochenski. Mentor: Molly Willging
Estradiol action regulates adipocyte lipolysis and thermogenesis via ER-a and ER-b, but the mechanism as to how estradiol does so is currently being researched. Additionally, there has been an increased onset of obesity in women after menopause. No clear relationship between estradiol action and adipocyte cell morphology in female nonhuman primates has been established. In past studies, total knockdown of ESR1 gene expression contributes to hypertrophy of white and brown adipocytes in rodent models. We tested whether decreased ESR1 gene expression in the ventromedial hypothalamus induced change in adipocyte structure. Results indicate a significant decrease in adipocyte area and circumference in response to the ESR1 knockdown treatment. Therefore, we suggest that adipocytes undergo hyperplasia, not hypertrophy, due to lack of estradiol action.
EFFECTS OF ESTRADIOL DEPRIVATION ON PANCREATIC ISLET MORPHOLOGY OF OVARIECTOMIZED FEMALE MARMOSETS
Taylor Byington, Mihika Sathe. Mentor: David Abbott
Estradiol (E2) is a female sex hormone that regulates the reproductive cycle. E2 depletion is a common side effect of taking letrozole, a drug that prevents the conversion of androgens to estrogen and is used to treat breast cancer. Previous studies in rodent models suggest that E2 deprivation leads to the accumulation of extracellular plaque in the pancreatic islets due to oxidative stress and apoptosis. This study aims to determine whether the same effects occur in non-human primates. We hypothesize that ovariectomized female marmosets undergoing total estradiol deprivation will have increased extracellular plaque in their pancreatic islets as compared to controls.
MEASURING THE EXPRESSION AND CYCLICITY OF ALOPECIA IN BREEDING AGE FEMALE RHESUS MACAQUES (MACACA MULATTA)
Morgan Cazares. Mentor: Peter J. Pierre
Alopecia is a condition of substantial hair loss from parts of the body where hair normally grows. Alopecia is commonly observed during pregnancy, however the reasons for hair loss are not well understood. Past research has suggested over- grooming and stress responses as factors that contribute to alopecia; however, the strength of the relationship between the “stress marker”, hair cortisol levels, and alopecia has been inconsistent. We evaluated 30 breeding age female Rhesus Macaques at different phases of pregnancy. Collecting coat images, we used contrast-based image analysis to evaluate variation in alopecia area and collected hair samples, for the potential development of alopecia biomarkers in this sub-popu- lation. We aim to describe and define the extent of alopecia to better understand the underlying factors that drive expression.
EFFECTS OF KISSPEPTIN-10 (KP10) ON THE TIMING OF PUBERTAL INITIATION
Veronica Goveas. Mentors: Ei Terasawa, Erica Gelman
Puberty is a complex developmental process involving hormonal changes that lead to the acquisition of reproductive capac- ity. The hypothalamo-pituitary-gonadal (HPG) axis regulates the timing of puberty, and kisspeptin has been implicated in the critical role of this process. However, the precise role of kisspeptin in regulating puberty onset remains unclear. This study aims to investigate the effects of the kisspeptin agonist (KP10) on puberty in female Rhesus macaques. Three pre- pubertal females received hourly pulsatile KP10 infusion, whereas controls received no treatment. Pubertal development was monitored by measuring the nipple volume, sex-skin growth, body weight and height changes, and hormonal levels. Our findings will shed light on the role of kisspeptin in regulating puberty and will have implications for understanding the onset of puberty in humans.
EFFECTS OF KISSPEPTIN 10 ON PUBERTY ONSET IN THE MALE RHESUS MONKEY
Val Hultgren. Mentors: Ei Terasawa, Erica Gelman
The neuropeptide kisspeptin in the hypothalamus is the most important upstream regulator for the release of GnRH (gonad- otropin releasing hormone) neurons. To understand the relationship between kisspeptin and GnRH neuronal systems, we examine the effects of the kisspeptin agonist, kisspeptin 10 (KP10) on a pair of juvenile male monkeys. Results indicated that although KP10 stimulated the testicular volume for 5-30 weeks of KP10 infusion, it returned to pre-infusion levels after its cessation, whereas no testicular volume changes in the control during the same period. Importantly, the spontaneous pubertal increase in testicular volume in the KP10 treated monkey had 4 months delay as compared to the control. Thus, it appears that premature KP10 infusion would cause adverse effects on the timing of puberty.
COGNITIVE AND MOTOR PERFORMANCE OF 1-YEAR-OLD RHESUS MACAQUES PRENATALLY EXPOSED TO ZIKA VIRUS
Dean Johnson. Mentor: Karla Ausderau
Previous studies have shown that up to 30% of congenital Zika-exposed infants express late-onset development, speech, and/or cognitive delay. It is unknown why some infants express deficits while others do not. The purpose of this study is to use a rhesus macaque model to compare the cognitive and motor abilities of 1-year-old prenatally exposed Zika macaques to a mock-injection group using a puzzle feeder task. The cognitive abilities will be measured by the highest level achieved on the puzzle and fine motor skills will be assessed by finger isolation to retrieve and move the treat through the puzzle feeder. Results will provide insight into the severity and timing of deficits in a non-human primate model of prenatal Zika exposure.
PREVALENCE OF POLYCYSTIC OVARY SYNDROME (PCOS)-LIKE OVARIAN MORPHOLOGY IN ADULT FEMALE RHESUS MACAQUES WITH NATURALLY OCCURRING HIGH TESTOSTERONE
Savannah Knaak, Suzanne Oriel. Mentor: David Abbott
In a pedigree of adult female rhesus macaques at the Wisconsin National Primate Research Center, we have identified those with naturally occurring high testosterone (T) levels and those with normal T levels. To gain insight into the impact of high T levels on PCOS-like ovarian morphology in women, we quantified ovarian follicle populations in adult female rhesus macaques with naturally occurring high T (n=4) and adult female rhesus macaques with normal T (n=4). The two groups were pair-matched in terms of age and weight. We hypothesize that adult female rhesus macaques with high T will have PCOS-like ovarian morphology compared to normal T female monkeys. Such findings would suggest that high T levels induce PCOS-like ovarian pathology.
ROLE OF NEUROESTRADIOL IN THE BRAIN: SEX DIFFERENCE
Stephanie Li Mentor: Ei Terasawa
Gonadotropin releasing hormone (GnRH) neurons in the hypothalamus controls reproductive function in both males and females. Despite the clear sex difference in reproductive function, the hypothalamus in primates is not sexually differentiated. Because neuroestradiol, synthesized in the brain, also plays a role in regulation of GnRH release in female macaques, this study examines whether neuroestradiol also plays a similar role in male macaques. To test the neuroestradiol’s role, castrated males were treated with high dose of estradiol benzoate along with the aromatase inhibitor, letrozole, which blocked the synthesis of estradiol from testosterone, while periodical blood samples for hormone analysis were obtained. Controls received estradiol benzoate and vehicle for letrozole. Findings from this study further clarify the sex difference and role of neuroestrodiol in the brain.
BIOLOGICALLY INSPIRED CONVOLUTIONAL NEURAL NETWORKS FOR 3D VISUAL PROCESSING
Yanru (Lillian) Li. Mentor: Ari Rosenberg
Our eyes sense two-dimensional (2D) projections of the environment, like a movie on a screen, yet we perceive the world as three-dimensional (3D). To successfully interact with objects in our dynamic environment, the visual system needs to reconstruct 3D representations from these 2D retinal projections. However, the neuronal computations underlying this process remain relatively unknown. To investigate these 2D-to-3D transformations, I trained a biologically inspired convo- lutional neural network (CNN) to perform various 3D visual discrimination tasks. By examining the properties of artificial networks that most resemble the brain areas thought to contribute to 3D processing, this work will provide insight into the underlying mechanisms and computations that allow the brain to achieve a robust representation of the 3D environment.
GIRK2 EXPRESSION IN THE SUBSTANTIA NIGRA OF HEMIPARKINSONIAN CYNOMOLGUS MACAQUES
Lindsey Neumann. Mentor: Marina Emborg
Girk2 is a neuronal protein expressed in dopaminergic neurons. In Parkinson’s disease, there is a dopaminergic neuronal loss in the substantia nigra pars compacta (SNpc), and girk2 expressing dopaminergic neurons seemed to be more vulnerable. Non-human primates are widely used as models of Parkinson’s, yet little is known about girk2 expression in their brains. Here we analyzed girk2 expression in the SN of cynomolgus macaques (n=5) that received a unilateral intracarotid arterial injection of the parkinsonian toxin MPTP and were euthanized 3 months later. Quantification of girk2 showed a significant unilateral loss of expression in the MPTP treated SN. These results demonstrate that girk2 is expressed in the SN of non-human primates and is affected by the parkinsonian drug MPTP.
ASSOCIATION OF ESTROGEN RECEPTOR GENE KNOCKDOWN WITH WEIGHT GAIN IN FEMALE NONHUMAN PRIMATES
Andi Pieczynski, Terrianna Lyles, Lillian Marrah. Mentor: David Abbott
This study looked to evaluate the presence of estrogen receptor alpha (ERα) gene knockdown in the hypothalamic arcuate nucleus (ARC) and ventromedial nucleus (VMN) of adult female rhesus macaques. The administration of a viral vector was monitored via MRI for ERα neuron targeting. Experimental monkeys (n=4) received shRNA encapsulated in adenoassociated virus 8 (AAV8) while the control monkeys (n=4) were injected with scrambled RNA (shRNA) with no gene targets. The retrospective expression quantification occurred approximately 11 months after gene silencing. This is one of the first studies that examines ERα in female nonhuman primates, and our findings suggest that it is important for metabolic regulation.
AN EXAMINATION OF HANDEDNESS AS A PREDICTOR OF TEMPERAMENT AND LEARNING ABILITY IN THE COMMON MARMOSET (CALLITHRIX JACCHUS)
Elizabeth Preuss. Mentor: Peter J. Pierre
Our investigation aims to determine the relationship that various metrics of handedness have to temperament and learning in the common marmoset. Twenty pair-housed marmosets (10 male, 10 female) performed the TUBE test and Box task under observation. We recorded which hand individuals used to interact(handedness), the initial time to contact novel objects(cautiousness), and the time needed to complete a task over multiple trials(learning). We hypothesize that there will be positive relationships between left-handedness and cautiousness as well as strength of handedness and accelerated learning. Describing relationships between sex, handedness, and temperament in this species will help clarify gaps in the current literature. Furthermore, addressing the connection between the strength of handedness and learning may illuminate the role lateralization plays in expanding cognitive capacity across species.
ASSESSING VIRAL POPULATION DYNAMICS IN PREGNANT NON-HUMAN PRIMATES WITH PROLONGED ZIKA VIRUS INFECTION
Liv Romanov. Mentor: Tom Friedrich
The potential for Zika virus (ZIKV) to cause fetal harm was first recognized during the Americas outbreak from 2015 to 2016. Prolonged infections (>21 days) have only been documented in pregnant people or pregnant non-human primates. The mechanism of prolonged ZIKV infection is poorly understood, but infection of the fetus or fetal compartment may be the source of replicating virus. I hypothesize that prolonged detection of ZIKV RNA in blood indicates ongoing viral replication in immunologically privileged sites such as the maternal-fetal interface (MFI). This study leverages next-generation sequencing to analyze ZIKV populations in a pregnant non-human primate model. This work will establish a novel model of virus persistence and enhance public health efforts to monitor for ZIKV genotypes with a propensity for fetal harm.
EFFECTS OF ESTRADIOL DEPRIVATION ON PANCREATIC ISLET MORPHOLOGY OF OVARIECTOMIZED FEMALE RHESUS MACAQUES
Mihika Sathe, Taylor Byington. Mentor: David Abbott
Estradiol (E2) is a female sex hormone that regulates the menstrual cycle. Studies in female rodents suggest that E2 depri- vation leads to accumulation of extracellular plaque in pancreatic islets. Subsequent diminished islet numbers of insulin- producing beta and other cells increase the likelihood of conversion to type 2 diabetes (T2D). The results of our previous study in marmoset monkeys, however, showed no such pathology. The purpose of the current study was to determine the effects of E2 deprivation on pancreatic islet pathology of female rhesus macaques. These monkeys share 93% of their genome with humans and are a more comprehensive model for humans. We hypothesize that total E2 deprivation will increase extracellular plaque in macaque pancreatic islets compared to controls and signs of T2D.
EFFECTS OF KISSPEPTIN 10 (KP10) ON FOOD INTAKE IN FEMALE MONKEYS
Suzanne Schott. Mentor: Ei Terasawa
Increases in the release of gonadotropin releasing hormone (GnRH) initiate puberty onset. However, the mechanism of the pubertal increase in GnRH is unclear. Because the neuropeptide kisspeptin is an important regulator for GnRH neurons in the hypothalamus, we examined the effects of the kisspeptin agonist, KP10 on puberty. Three of six juvenile female monkeys received hourly infusion KP10, while the other three juvenile females were assigned controls. Food intake was measured daily, and body weight was assessed weekly. Preliminary results indicated that while KP10 infused females exhibited signs of puberty, it did not alter the amount of food intake or the body weight. It appears that the KP10 action on GnRH neurons is independent from the mechanism controlling food intake and subsequent body weight regulation.
ROLE OF BROWN FAT BETA ADRENERGIC RECEPTORS AND EXTRA OVARIAN ESTRADIOL IN REGULATING FEMALE BODY WEIGHT
Sindhu Shankar. Mentors: David Abbott, Molly Willging
Almost half of the United States adult population is obese. Obesity, defined clinically as a body mass index ≥30, is characterized by positive energy balance resulting in lipid accumulation in white adipocytes. Studies in female rodents have implicated a lack of estradiol (E2) action, via estrogen receptor alpha (ESR1) in the hypothalamus, as a primary culprit. E2/ESR1-enabled beta-adrenergic receptor signaling in brown adipocytes opposes weight gain by thermogenesis. Women depleted of E2 through menopause are likely to develop obesity. Studying the onset of obesity in women is ethically challenging, thus, a nonhuman primate (NHP), sharing many functional processes, can serve as a translational model. Investigating brown adipocyte function in these E2-depleted NHPs presents a potential for finding new therapeutic targets for obese women.
HERITABILITY OF HYPERANDROGENISM IN FEMALE RHESUS MACAQUES EXHIBITING NATURALLY OCCURRING PCOS-RELATED TRAITS
Yuhan Sun. Mentor: David Abbott
Polycystic ovary syndrome (PCOS) affects many women; is characterized by high testosterone (T) levels, polycystic ovaries, and irregular menstrual cycles; and is associated with insulin resistance, increased BMI, and infertility. Studying nonhuman primates (NHP) could provide valuable insight into the causes of PCOS given NHP genetic and physiological similarity to ourselves. In previous studies, we found PCOS-like characteristics in female rhesus macaques with naturally high levels of T. In this study, we aim to investigate the heritability of high T levels and PCOS developmental origins in a laboratory macaque population. By analyzing body measurements and steroid hormone levels in naturally occurring high T females, we hope to gain a better understanding of the heritability of traits associated with PCOS in women.
OVARIAN AND EXTRA-OVARIAN ESTRADIOL REGULATION OF CALORIC INTAKE, LOCOMOTION, AND ENERGY EXPENDITURE IN ADULT FEMALE RHESUS MONKEYS
Alexis Woida, Samantha Williams. Mentors: David Abbott, Molly Willging
Declining serum estradiol (E2) levels during menopausal transition are associated with heightened risks for metabolic disease. While ovariectomy (OVX) in rodents enables obesity, OVX in nonhuman primates (NHPs) inconsistently alters weight gain. We therefore hypothesized that in female NHPs, extra-ovarian E2 provides key support for metabolic homeostasis. Twenty adult female rhesus monkeys were OVX and received: 1) E2-containing capsules and letrozole, or empty capsules and either 2) vehicle or 3) letrozole treatment. Data on food intake, physical activity, energy expenditure, and body fat distribution were collected. The results of this study could provide important insights into the relationship between nutrition, physical activity, and body composition that could have significant implications for the development of effective interventions to prevent and manage obesity and related health conditions.
FMR1-DEFICIENT PRIMATE NEURONS EXHIBIT INCREASED OXIDATIVE STRESS LEVELS
Natalie Wolkoff. Mentors: Minjie Shen, Carissa Sirois
Fragile X Syndrome (FXS) results from Fragile X Messenger Ribonucleoprotein (FMR1) deficiency and is a prevalent inherited intellectual disability. FXS results in cognitive impairment, behavioral deficits, and neuronal developmental and functional impairment. The mechanisms behind FMR1 deficiency leading to these phenotypes are not fully understood. Previous studies show that FMR1-deficient immature neurons in mice exhibit fragmented mitochondria, impaired mitochondrial function, and increased oxidative stress. This study aims to identify whether FMR1-deficient human and non-human primate neurons also display these phenotypes and if treatment could rescue them. Results reveal altered mitochondrial morphology and elevated nitrotyrosine levels in FMR1-deficient human and primate neurons. Treatment with leflunomide mitigated these cellular phenotypes and decreased oxidative stress levels in FXS neurons. These findings provide critical data for potential therapeutic development.