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Biology of Reproduction May 2023Some transmasculine individuals may be interested in pausing gender-affirming testosterone therapy and carrying a pregnancy. The ovarian impact of taking and pausing...
Some transmasculine individuals may be interested in pausing gender-affirming testosterone therapy and carrying a pregnancy. The ovarian impact of taking and pausing testosterone is not completely understood. The objective of this study was to utilize a mouse model mimicking transmasculine testosterone therapy to characterize the ovarian dynamics following testosterone cessation. We injected postpubertal 9-10-week-old female C57BL/6N mice once weekly with 0.9 mg of testosterone enanthate or a vehicle control for 6 weeks. All testosterone-treated mice stopped cycling and demonstrated persistent diestrus within 1 week of starting testosterone, while control mice cycled regularly. After 6 weeks of testosterone therapy, one group of testosterone-treated mice and age-matched vehicle-treated diestrus controls were sacrificed. Another group of testosterone-treated mice were maintained after stopping testosterone therapy and were sacrificed in diestrus four cycles after the resumption of cyclicity along with age-matched vehicle-treated controls. Ovarian histological analysis revealed stromal changes with clusters of large round cells in the post testosterone group as compared to both age-matched controls and mice at 6 weeks on testosterone. These clusters exhibited periodic acid-Schiff staining, which has been previously reported in multinucleated macrophages in aging mouse ovaries. Notably, many of these cells also demonstrated positive staining for macrophage markers CD68 and CD11b. Ovarian ribonucleic acid-sequencing found upregulation of immune pathways post testosterone as compared to age-matched controls and ovaries at 6 weeks on testosterone. Although functional significance remains unknown, further attention to the ovarian stroma may be relevant for transmasculine people interested in pausing testosterone to carry a pregnancy.
Topics: Pregnancy; Female; Mice; Animals; Humans; Ovary; Transgender Persons; Mice, Inbred C57BL; Testosterone; Disease Models, Animal; Mice, Inbred Strains
PubMed: 36790125
DOI: 10.1093/biolre/ioad019 -
Animals : An Open Access Journal From... Jan 2023Myeloperoxidase (MPO), as a marker of neutrophil activation, has been associated with equine endometritis. However, in absence of inflammation, MPO is constantly...
Myeloperoxidase (MPO), as a marker of neutrophil activation, has been associated with equine endometritis. However, in absence of inflammation, MPO is constantly detected in the uterine lumen of estrous mares. The aim of this study was to characterize MPO in the uterus of mares under physiological conditions as a first step to better understand the role of this enzyme in equine reproduction. Total and active MPO concentrations were determined, by ELISA and SIEFED assay, respectively, in low-volume lavages from mares in estrus ( = 26), diestrus ( = 18) and anestrus ( = 8) in absence of endometritis. Immunohistochemical analysis was performed on 21 endometrial biopsies randomly selected: estrus ( = 11), diestrus ( = 6) and anestrus ( = 4). MPO, although mostly enzymatically inactive, was present in highly variable concentrations in uterine lavages in all studied phases, with elevated concentrations in estrus and anestrus, while in diestrus, concentrations were much lower. Intracytoplasmic immunoexpression of MPO was detected in the endometrial epithelial cells, neutrophils and glandular secretions. Maximal expression was observed during estrus in mid and basal glands with a predominant intracytoplasmic apical reinforcement. In diestrus, immunopositive glands were sporadic. In anestrus, only the luminal epithelium showed residual MPO immunostaining. These results confirm a constant presence of MPO in the uterine lumen of mares in absence of inflammation, probably as part of the uterine mucosal immune system, and suggest that endometrial cells are a source of uterine MPO under physiological cyclic conditions.
PubMed: 36766264
DOI: 10.3390/ani13030375 -
The Journal of Comparative Neurology May 2023An important factor that can modulate neuron properties is sex-specific hormone fluctuations, including the human menstrual cycle and rat estrous cycle in adult females....
An important factor that can modulate neuron properties is sex-specific hormone fluctuations, including the human menstrual cycle and rat estrous cycle in adult females. Considering the striatal brain regions, the nucleus accumbens (NAc) core, NAc shell, and caudate-putamen (CPu), the estrous cycle has previously been shown to impact relevant behaviors and disorders, neuromodulator action, and medium spiny neuron (MSN) electrophysiology. Whether the estrous cycle impacts MSN dendritic spine attributes has not yet been examined, even though MSN spines and glutamatergic synapse properties are sensitive to exogenously applied estradiol. Thus, we hypothesized that MSN dendritic spine attributes would differ by estrous cycle phase. To test this hypothesis, brains from adult male rats and female rats in diestrus, proestrus AM, proestrus PM, and estrus were processed for Rapid Golgi-Cox staining. MSN dendritic spine density, size, and type were analyzed in the NAc core, NAc shell, and CPu. Overall spine size differed across estrous cycle phases in female NAc core and NAc shell, and spine length differed across estrous cycle phase in NAc shell and CPu. Consistent with previous work, dendritic spine density was increased in the NAc core compared to the NAc shell and CPu, independent of sex and estrous cycle. Spine attributes in all striatal regions did not differ by sex when estrous cycle was disregarded. These results indicate, for the first time, that estrous cycle phase impacts dendritic spine plasticity in striatal regions, providing a neuroanatomical avenue by which sex-specific hormone fluctuations can impact striatal function and disorders.
Topics: Humans; Rats; Female; Male; Animals; Nucleus Accumbens; Dendritic Spines; Rats, Sprague-Dawley; Putamen; Estrous Cycle; Estradiol
PubMed: 36756791
DOI: 10.1002/cne.25460 -
Scientific Reports Feb 2023The present study aimed to investigate whether time-restricted feeding (TRF) ameliorates metabolic and reproductive phenotypes in a letrozole-induced mouse model of...
The present study aimed to investigate whether time-restricted feeding (TRF) ameliorates metabolic and reproductive phenotypes in a letrozole-induced mouse model of polycystic ovary syndrome (PCOS). Sixty female C57BL/6 N mice were randomly divided into two groups according to the type of food received: either a chow or a 60% high-fat diet. Those mice were subcutaneously implanted with letrozole or placebo pellets at four weeks of age. Then, letrozole-treated mice were randomly assigned to different feeding regimens: (1) TRF for 4 h (ZT12-ZT16) or (2) ad libitum diet. After 4 weeks of dietary intervention, estrous cycles were determined with daily vaginal smear examination, and serial tail-tip blood sampling was performed at 5-min intervals for 2 h to measure the luteinizing hormone (LH) pulse frequency, amplitude, and mean LH levels in the diestrus cycle stage. Letrozole-treated mice in the ad libitum group demonstrated multiple PCOS-like phenotypes including ovulatory dysfunction, polycystic ovaries, and increased body weight, parametrial fat weight, adipocyte size and inflammation, and higher expression of Cyp17, Cyp19, and Fshr in the ovary, and Kiss1r and Gnrh in the hypothalamus, elevated serum testosterone levels, and more rapid and elevated LH pulsatility, with increased pulse frequency, amplitude, and mean levels in the diestrus stage, compared with the controls. After TRF for 4 weeks, those phenotypes reverted to normal levels in letrozole-treated mice, except the percentage of diestrus cycles indicating the arrest of estrous cycling which did not differ between the TRF and ad libitum groups. Our results demonstrate that TRF has therapeutic effects on the reproductive and metabolic phenotypes of a letrozole-induced mouse model of PCOS.
Topics: Humans; Female; Mice; Animals; Letrozole; Polycystic Ovary Syndrome; Mice, Inbred C57BL; Luteinizing Hormone; Disease Models, Animal
PubMed: 36732546
DOI: 10.1038/s41598-023-28260-5 -
BioRxiv : the Preprint Server For... Jan 2023Lateralization of hippocampal function is indicated by varied outcomes of patients with neurological disorders that selectively affect one hemisphere of this structure,...
Lateralization of hippocampal function is indicated by varied outcomes of patients with neurological disorders that selectively affect one hemisphere of this structure, such as temporal lobe epilepsy (TLE). The intrahippocampal kainic acid (IHKA) injection model of TLE allows for targeted damage to the left or right hippocampus, enabling systematic comparison of effects of left-right asymmetry on seizure and non-seizure outcomes. Although varying non-seizure phenotypic outcomes based on injection side in dorsal hippocampus were recently evaluated in this model, differences in chronic seizure patterns in left- (IHKA-L) vs. right-injected (IHKA-R) IHKA animals have yet to be evaluated. Here, we evaluated hippocampal seizure incidence in male and female IHKA-L and IHKA-R mice. Females displayed increased electrographic seizure activity compared to males at both 2 months and 4 months post-injection (mpi). In addition, IHKA-L females showed higher seizure frequency than IHKA-R on diestrus and estrus at 2 mpi, but seizure duration and time in seizures were only higher in IHKA-L females on diestrus. These cycle stage-associated changes, however, did not persist to 4 mpi. Furthermore, this lateralized difference in seizure burden was not observed in males. These results indicate for the first time that the side of IHKA injection can shape chronic electrographic seizure burden. Overall, these results demonstrate a female-specific left-right asymmetry in hippocampal function can interact with estrous cycle stage to shape chronic seizures in mice with epilepsy, with implications for neural activity and behavior in both normal and disease states.
PubMed: 36712086
DOI: 10.1101/2023.01.20.524965 -
Animals : An Open Access Journal From... Jan 2023The behaviour of oestrous mares is well-known in horse breeding. However, alterations in their physiological and behavioural indices during the whole oestrous cycle are...
The behaviour of oestrous mares is well-known in horse breeding. However, alterations in their physiological and behavioural indices during the whole oestrous cycle are scarcely known. The objective of the study was to analyse changes in cardiac activity variables, rectal and superficial temperatures, behaviour towards humans and conspecifics, and the time of standing and locomotor activity in mares during their oestrous cycle. Fifteen adult mares in oestrus were examined in the morning and evening (six successive days) and in dioestrus (five days-once every third day). The oscillation of physiological and behavioural variables accompanies changes in mares' sexual behaviour. Most physiological variables studied in oestrus indicate the elevated activity of the adrenergic nervous system and, opposite to that, both behaviour towards humans and conspecifics and the time of standing relate to a relaxed state. The end of oestrus, manifested by a rapid decrease in most of the physiological variables studied, is followed by changes of behavioural variables at the beginning of dioestrus. The time of locomotor activity arises at the end of oestrus. The outcomes may contribute to the knowledge of, among others, mare owners who evaluate the oestrus by mares' sexual behaviours without regarding other rhythmically changing variables.
PubMed: 36670751
DOI: 10.3390/ani13020211 -
Journal of Applied Physiology... Mar 2023We recently showed that in male rats, orexin contributes to the hypoxic ventilatory response (HVR), with a stronger effect in the active phase. The effect of orexin on...
We recently showed that in male rats, orexin contributes to the hypoxic ventilatory response (HVR), with a stronger effect in the active phase. The effect of orexin on the HVR in females has not been investigated. As estrogen can inhibit orexin neurons, here we hypothesized that orexin neurons are activated by hypoxia and facilitate the HVR only in diestrus, when estrogen is low. We exposed female rats ( = 10) to near-isocapnic hypoxia ([Formula: see text] from 0.21 to 0.09) over ∼5 min, after vehicle and again after suvorexant (a dual OxR antagonist; 20 mg/kg ip), with ventilation measured using whole body plethysmography. Each rat was tested in proestrus or estrus (p/estrus), and again in diestrus, during both inactive and active phases. We also performed immunohistochemistry (IHC) to determine the proportion of orexin neurons activated by acute hypoxia during diestrus ( = 6) or proestrus/estrus ( = 6) in the active phase. In the inactive phase, the HVR was unaffected by OxR blockade, irrespective of estrus stage. In the active phase, the effect of OxR blockade depended on stage: the slope of the HVR was significantly reduced by OxR blockade only during diestrus. IHC revealed that hypoxia activated more orexin neurons during diestrus compared with p/estrus. We conclude that in females, orexin neurons are activated by hypoxia and contribute to the HVR only in diestrus when estrogen levels are low. Stage of the estrus cycle should be considered when examining the physiological function of orexin neurons in females. We previously showed that orexin facilitates the hypoxic ventilatory response (HVR) of adult male rats during the active phase. Others have shown that estrogen inhibits orexin neurons. Here we show that orexin neurons are activated by hypoxia and facilitate the HVR of adult female rats during the active phase, but only in diestrus. These data suggest that orexin neurons facilitate the HVR in females when they are free from the inhibitory effects of estrogen.
Topics: Animals; Female; Rats; Diestrus; Estrogens; Estrus; Hypoxia; Orexins; Pulmonary Ventilation
PubMed: 36656978
DOI: 10.1152/japplphysiol.00661.2022 -
Animals : An Open Access Journal From... Dec 2022Galectins are a family of proteins that bind to glycans, acting in a cytokine-like manner throughout the body. In the majority of mammalians, galectins have been found...
Galectins are a family of proteins that bind to glycans, acting in a cytokine-like manner throughout the body. In the majority of mammalians, galectins have been found to be involved in pregnancy maintenance, but few studies have evaluated this in the horse. Therefore, the objective of this study was to examine the expression of various galectins in pregnant and nonpregnant mares. Next-generation RNA sequencing was performed on the chorioallantois and endometrium of healthy pregnant mares at 120, 180, 300, and 330 days of gestation (n = 4/stage), as well as 45-day chorioallantois (n = 4), postpartum chorioallantois (n = 3), and diestrus endometrium (n = 3). In the endometrium, galectin-1 and galectin-13 were found in the highest expression in the nonpregnant mare, with decreasing levels of expression noted throughout gestation. In contrast, galectin-8 and galectin-12 were found to be the lowest in the nonpregnant mare and reached the highest expression levels in mid-gestation before declining as parturition neared. In the chorioallantois, galectin-1, galectin-3, and galectin-3BP were found to have heightened expression levels at 45 d of gestation, with lesser expression levels noted throughout gestation. In contrast, galectin-9, galectin-12, and galectin-13 experienced the highest expression levels in the late-term chorioallantois (300 d/330 d), with lesser expression noted in early- to mid-gestation. Of note, galectin-1, galectin-3BP, galectin-9, galectin-12, and galectin-13 all experienced the lowest expression levels in the postpartum placenta, with heightened expression noted during gestation. In conclusion, galectins appear to be involved in equine pregnancy, and this is dependent on both the tissue within the feto-maternal interface and the specific galectin involved.
PubMed: 36611738
DOI: 10.3390/ani13010129 -
Animals : An Open Access Journal From... Dec 2022Eight non-bred, non-pregnant, regularly cycling Caribbean jennies were examined daily via transrectal ultrasound to define the ovarian and uterine dynamics during four...
Eight non-bred, non-pregnant, regularly cycling Caribbean jennies were examined daily via transrectal ultrasound to define the ovarian and uterine dynamics during four consecutive estrous cycles. Blood samples were collected every other day for progesterone analysis. The mean (±SD) overall inter-ovulatory interval across all donkeys and cycles was 22.93 ± 1.99 days. The maximum follicular diameter was 34.6 ± 2.9 mm. A two-wave pattern was evident in 97% (30/31) of the cycles. The emergence of the future dominant follicle and the largest subordinate follicle of the major primary wave coincided on Day 5.7 ± 3.6 post-ovulation, whereas the secondary wave emerged on Day 19.8 ± 2.9 during estrus of the previous cycle or early diestrus. The secondary wave was often minor (93%, 28/30 cycles). Follicular deviation occurred 8.2 ± 1.4 days before the subsequent ovulation. Luteal volume increased for the first four days after ovulation and reached a maximum volume of 8.5 ± 2.7 mm3 at Day 5.4 ± 0.4, before gradually regressing after Day 15. Serum progesterone concentration increased from Day 1 after ovulation, peaking at 27.0 ± 9.6 ng/mL between 7 and 10 days after ovulation. Progesterone concentration dropped precipitously around Day 15 after ovulation and was below 2 ng/mL around Day 17 ± 2. A day effect (p < 0.0001) was observed for corpus luteum’s volume, progesterone concentration, and uterine tone, but not for endometrial edema (p > 0.05). This study helps to clarify and define normal estrous characteristics of jennies in the Eastern Caribbean.
PubMed: 36611684
DOI: 10.3390/ani13010074 -
Heliyon Dec 2022The medial preoptic (MPN) and the ventromedial hypothalamic nuclei (VMN) modulate the estrogen receptor (ER)-dependent female sexual behavior, a response that is...
The medial preoptic (MPN) and the ventromedial hypothalamic nuclei (VMN) modulate the estrogen receptor (ER)-dependent female sexual behavior, a response that is inhibited by tamoxifen (TAM), a modulator of the steroid receptor activation. With the objective to assess TAM action in the brain areas involved in the modulation sexual cues, an animal model on long-term TAM therapy to intact female rats, was used to mimic the 5-year prophylactic TAM therapy offered to women at higher risk of breast cancer. After three months treatment, female sexual behavior with a stud male rat was evaluated. Upon sacrifice, the brains were removed and the MPN and the ventrolateral division of the VMN were screened for the effects of TAM in the expression of ERα, ERβ and progesterone receptor. Results show that TAM inhibited the receptive component of the female sexual behavior. Even though TAM decreased estrogen and progesterone levels to values similar to the ones of estrous and diestrus rats, the biochemical data failed to demonstrate such possible causation for the behavioral response. In fact, TAM administration induced a constant low level of ovarian hormones that changed the pattern of ER and PR expression as well as receptor co-expression in the brain areas regulating the behavioral response, dissimilar to the ones seen in the cycle phases with the same low hormone levels. Nevertheless, present data suggests that by affecting ER- and/or PR-dependent mechanisms, TAM may modulate the hypothalamus, a region known to participate in several social behaviors.
PubMed: 36593822
DOI: 10.1016/j.heliyon.2022.e12362