Macrophages in juvenile pig testis: Link with increase in Sertoli cells induced by oestradiol suppression.

Macrophage presence and location were evaluated in juvenile boar testes at the end of the first wave of Sertoli cell proliferation. Macrophage presence was compared in littermate boars treated with letrozole, a treatment which extended this first wave of proliferation beyond the sampling timepoint. Macrophages were identified as the CD68 positive cells following immunohistochemical labelling of paraffin sections and parenchymal macrophages enumerated. Macrophages present in a layer beneath the tunica albuginea received a score based on density and thickness of this layer. Density within the testicular parenchyma was highly variable in vehicle-treated boars (>100-fold) and did not differ from that observed in the letrozole-treated littermates. However, the macrophage layer beneath the tunica albuginea was denser and thicker in the letrozole-treated animals than in their vehicle-treated littermates. This suggests that macrophages might be involved in the letrozole-induced prolongation of Sertoli cell proliferation.

Long term effects of chronic intranasal oxytocin on adult pair bonding behavior and brain glucose uptake in titi monkeys (Plecturocebus cupreus).

Intranasal oxytocin (IN OXT) administration has been proposed as a pharmacological treatment for a range of biomedical conditions including neurodevelopmental disorders. However, studies evaluating the potential long-lasting effects of chronic IN OXT during development are still scarce. Here we conducted a follow-up study of a cohort of adult titi monkeys that received intranasal oxytocin 0.8 IU/kg (n = 15) or saline (n = 14) daily for six months during their juvenile period (12 to 18 months of age), with the goal of evaluating the potential long-lasting behavioral and neural effects one year post-treatment. Subjects were paired with an opposite-sex mate at 30 months of age (one year post-treatment). We examined pair affiliative behavior in the home cage during the first four months and tested for behavioral components of pair bonding at one week and four months post-pairing. We assessed long-term changes in brain glucose uptake using 18FDG positron emission tomography (PET) scans. Our results showed that OXT-treated animals were more affiliative across a number of measures, including tail twining, compared to SAL treated subjects (tail twining is considered the "highest" type of affiliation in titi monkeys). Neuroimaging showed no treatment differences in glucose uptake between SAL and OXT-treated animals; however, females showed higher glucose uptake in whole brain at 23 months, and in both the whole brain and the social salience network at 33 months of age compared to males. Our results suggest that chronic IN OXT administration during development can have long-term effects on adult social behavior.

Regulation of apical blebbing in the porcine epididymis.

Apical blebbing, a non-classical secretion mechanism, occurs in the mature porcine epididymis as part of its normal function. Proteins secreted by this mechanism contribute to the modification of the sperm plasma membrane during epididymal transit and are thought to contribute to acquisition of fertilizing ability. However, little is known about the regulation of this secretion mechanism in an in vivo model. Previous work demonstrated apical blebbing in the epididymis developed pubertally, suggesting androgens, sperm or other luminal factors regulated this process. Hence, the objective was to evaluate the hypothesized regulation of apical blebbing in the epididymis of pubertal boars by androgens and luminal factors. Androgen receptor blockade (flutamide) and surgical interventions (efferent duct ligation, orchidectomy or transection of the caput epididymis) were used to alter signaling, and the subsequent effects on apical blebbing were evaluated histologically. Apical blebbing was not altered by androgen receptor blockade with flutamide, but was significantly reduced 24 h after efferent duct ligation and after orchidectomy, treatments that eliminated luminal flow from the testis (P < 0.05). Like efferent duct ligation, epididymal transection altered luminal flow without removing the androgen source and significantly reduced the appearance of apical blebbing (P < 0.05). In conclusion, apical blebbing in the porcine epididymis appears to be regulated by luminal factors.

The dynamic steroid landscape of equine pregnancy mapped by mass spectrometry.

Liquid chromatography-tandem mass spectrometry (LC-MS/MS) allowed comprehensive analysis of various steroids detectable in plasma throughout equine gestation. Mares (n=9) were bled serially until they foaled. Certain steroids dominated the profile at different stages of gestation, clearly defining key physiological and developmental transitions. The period (weeks 6-20) coincident with equine chorionic gonadotropic (eCG) stimulation of primary corpora lutea and subsequent formation of secondary luteal structures was defined by increased progesterone, 17OH-progesterone and androstenedione, all Δ4 steroids. The 5α-reduced metabolite of progesterone, dihydroprogesterone (DHP) paralleled progesterone secretion at less than half the concentration until week 12 of gestation when progesterone began to decline but DHP concentrations continued to increase. DHP exceeded progesterone concentrations by week 16, clearly defining the luteo-placental shift in pregnane synthesis from primarily ovarian to primarily placental. The period corresponding to the growth of fetal gonads was defined by increasing dehydroepiandrosterone and pregnenolone (Δ5 steroids) concentrations from week 14, peaking at week 34 and declining to term. Metabolites of DHP (including allopregnanolone) dominated the steroid profile in late gestation, some exceeding DHP by weeks 13 or 14 and near term by almost tenfold. Thus Δ4 steroids dominated during ovarian stimulation by eCG, inversion of the ratio of progesterone: DHP (increasing 5α-pregnanes) marked the luteo-placental shift, Δ5 steroids defined fetal gonadal growth and 5α-reduced metabolites of DHP dominated the steroid profile in mid- to late-gestation. Comprehensive LC-MS/MS steroid analysis provides opportunities to better monitor the physiology and the progress of equine pregnancies, including fetal development.

Proteomic Characterization of Pig Sperm Anterior Head Plasma Membrane Reveals Roles of Acrosomal Proteins in ZP3 Binding.

The sperm anterior head plasma membrane (APM) is the site where sperm first bind to the zona pellucida (ZP). This binding reaches the maximum following the sperm capacitation process. To gain a better understanding of the sperm-ZP binding mechanisms, we compared protein profiles obtained from mass spectrometry of APM vesicles isolated from non-capacitated and capacitated sperm. The results revealed that ZP-binding proteins were the most abundant group of proteins, with a number of them showing increased levels in capacitated sperm. Blue native gel electrophoresis and far-western blotting revealed presence of high molecular weight (HMW) protein complexes in APM vesicles of both non-capacitated and capacitated sperm, but the complexes (∼750-1300 kDa) from capacitated sperm possessed much higher binding capacity to pig ZP3 glycoprotein. Proteomic analyses indicated that a number of proteins known for their acrosome localization, including zonadhesin, proacrosin/acrosin and ACRBP, were components of capacitated APM HMW complexes, with zonadhesin being the most enriched protein. Our immunofluorescence results further demonstrated that a fraction of these acrosomal proteins was transported to the surface of live acrosome-intact sperm during capacitation. Co-immunoprecipitation indicated that zonadhesin, proacrosin/acrosin and ACRBP interacted with each other and they may traffic as a complex from the acrosome to the sperm surface. Finally, the significance of zonadhesin in the binding of APM HMW complexes to pig ZP3 was demonstrated; the binding ability was decreased following treatment of the complexes with anti-zonadhesin antibody. Our results suggested that acrosomal proteins, especially zonadhesin, played roles in the initial sperm-ZP binding during capacitation.

Porcine sertoli cell proliferation after androgen receptor inactivation.

Sertoli cell proliferation in neonatal boars is potentially androgen dependent. Hence, the immediate objective was to evaluate effects of androgen receptor-mediated signaling on the first wave of Sertoli cell proliferation. The experimental design employed littermate pairs of boars with one member assigned to receive a daily oral dose of flutamide, an androgen receptor antagonist, beginning at 1 wk of age and the littermate the canola oil vehicle. Experiment 1 examined the response at 6.5 wk of age after completion of the first wave of Sertoli cell proliferation, and experiment 2 examined the response at 11 wk of age after initiation of the second wave of Sertoli cell proliferation. Experiment 3 was designed to evaluate initial responses at 2, 3, or 4 wk of age. Additional littermates from four of the litters evaluated at 2 wk of age were hemicastrated at 8 days of age. Testis weight increased approximately 50% in the flutamide-treated boars compared with vehicle-treated littermates (P = 0.01) by 6.5 wk of age. Approximately 80% more Sertoli cells/testis were present in flutamide-treated boars at 6.5 wk of age compared with their vehicle-treated littermates (P < 0.01). Animals that were hemicastrated at 8 days of age had more Sertoli cells/testis than their intact littermates at 2 wk of age (P < 0.01), but flutamide inhibited the hemicastration response. Androgen receptor antagonism during postnatal Sertoli cell proliferation increases Sertoli cell numbers, as does hemicastration, but receptor antagonism initially inhibits Sertoli cell proliferation induced by hemicastration.

Reduced endogenous estrogen and hemicastration interact synergistically to increase porcine sertoli cell proliferation.

Both reduced endogenous estrogen and hemicastration stimulate proliferation of porcine Sertoli cells. The objective of these experiments was to compare the temporal patterns of response to each stimulus with the response to the combined stimuli as indications of shared or separate mechanisms. Within a replicate, one littermate was treated weekly with canola oil vehicle and remained intact; a second littermate was treated weekly with vehicle, and one testis was removed at Day 8; a third littermate was treated weekly with the aromatase inhibitor letrozole to reduce endogenous estrogens and remained intact; and the fourth littermate was treated weekly with letrozole, and one testis was removed at Day 8. Four replicates were evaluated at 2 wk of age, five replicates evaluated at 6.5 wk of age, and five replicates were evaluated at 11 wk of age, with treatment ceasing at 6 wk of age. Numbers of Sertoli cells were determined following GATA4 labeling using the optical dissector method. Levels of estradiol, estrogen conjugates, follicle-stimulating hormone (FSH), luteinizing hormone (LH), and inhibin were determined by radioimmunoassay. Hemicastration appeared to have a rapid effect on Sertoli cell proliferation, but letrozole treatment had no apparent effect on Sertoli cell numbers at 2 wk of age. Both letrozole treatment and hemicastration had stimulated Sertoli cell proliferation by 6.5 wk of age, although the magnitude of the hemicastration response was much greater. Letrozole appeared to have minimal interaction with hemicastration at this age. Letrozole and hemicastration together increased Sertoli cell numbers at 11 wk of age compared with either treatment alone. Estradiol and estrogen conjugates were dramatically reduced by aromatase inhibition as anticipated; treatment-induced changes in inhibin, LH, or FSH were minimal. Differences in timing of response and positive interaction at 11 wk of age suggest that hemicastration and letrozole stimulate proliferation of Sertoli cells by two initially different pathways.

Gene Expression in Porcine Bulbourethral Glands.

The porcine bulbourethral glands produce a gel-type secretion. Although the role of these contributions to reproductive success remains murky, the bulbourethral glands are major accessory sex glands in this species. Isometric growth in the early neonatal interval is followed by allometric growth in the late juvenile interval (6 to 11 weeks of age), while circulating endogenous steroids are low. The rate of allometric growth increases during the peripuberal interval (16 to 20 weeks of age) when systemic testosterone is relatively high. Gene expression for androgen receptor (AR) and for the steroid 5 alpha-reductase 2 (SRD5A2) enzyme that synthesizes the more potent androgen dihydrotestosterone from its precursor was evaluated by qPCR analyses of bulbourethral gland tissue. Tissues were collected from control boars (2 weeks to 40 weeks of age) and from littermates of these boars treated with letrozole to suppress endogenous estrogen synthesis. Gene expression for these two key proteins in androgen signaling was quite low during the initial allometric growth in the late juvenile and prepuberal intervals, suggesting that this initial growth was not primarily stimulated by androgens. These observations are consistent with a more direct estrogen-mediated inhibition of growth via GPER previously proposed, with the sensitivity extending into the late juvenile interval when estrogens as well as androgens are normally relatively low.

Development of Porcine Accessory Sex Glands.

Accessory sex glands are recognized as targets of human disease and may have roles in reproductive success in livestock. The current experiments evaluated the influences of endogenous steroids on the development of porcine accessory sex glands, primarily in the neonatal period. When the aromatase inhibitor, letrozole, was used to inhibit the production of endogenous estrogens in the postnatal interval, growth of the seminal vesicles, prostate, and bulbourethral glands was stimulated. The weights of seminal vesicles, prostate, and bulbourethral glands approximately doubled at 6.5 weeks of age when the reduction in endogenous estrogens began at 1 week of age (p < 0.01). However, by 20 and 40 weeks of age, the weights of accessory sex glands were similar between the letrozole-treated boars and the vehicle-treated littermates indicating the growth stimulation was a transient effect when the treatment interval was short. The presence of both classical nuclear estrogen receptors and the G protein-coupled estrogen receptor in neonatal accessory sex glands indicated multiple signaling pathways might mediate the growth inhibition by endogenous estrogens. The absence of a detectable response when the classical estrogen receptors were blocked with fulvestrant (or when the androgen receptor was blocked with flutamide) suggests that endogenous estrogens act through the G protein-coupled estrogen receptor to inhibit the development of accessory sex glands during this neonatal to early juvenile interval.

Anti-Müllerian hormone and inhibin-B concentrations vary cyclically in nonovulating queens within reference ranges established for determining gonadal status in cats.

OBJECTIVE: To define cyclic changes in anti-Müllerian hormone (AMH), inhibin-B, and progesterone concentrations and establish statistically valid, population-based clinical reference ranges in queens. ANIMALS: Cyclic queens (fertile, n = 6; infertile, 6) from an institutional breeding colony were blood sampled longitudinally, each for over 2 months, between November 2021 and February 2022, and residual serum samples from intact (n = 205) and ovariohysterectomized (49) queens from clinical submissions were used to establish reference ranges for intact and spayed females. METHODS: AMH and inhibin-B were measured using commercially available ELISAs, progesterone was measured using an in-house ELISA, and 90% CIs were calculated from these data. RESULTS: AMH and inhibin-B fluctuated in a highly correlated, cyclic pattern in 3 queens that did not ovulate immediately, whereas AMH declined as progesterone increased, indicative of ovulation, which occurred spontaneously early in the sampling period in 3 others; statistically valid reference ranges were established in intact and ovariohysterectomized females. CLINICAL RELEVANCE: Cyclic changes in hormone profiles were defined, providing relevant context for interpreting results in cases seeking to determine gonadal status (presence or absence of gonadal tissue) on the basis of established, population-based reference ranges reported here for cats for the first time.

Gender disparity in survival of early porcine fetuses due to altered androgen receptor or associated U2 spliceosome component.

A single locus on the X chromosome codes for androgen receptor (AR) although this gene is subject to alternative splicing. AR is expressed in multiple tissues in males and females and is essential for reproductive success in the male. Since male and female mice are viable following naturally occurring and engineered loss of function with male mice infertile as anticipated, functional deletion of AR in pigs was hypothesized to provide a genetic containment strategy for males with edited genomes. In addition, deletion of AR might be a method to manage boar taint, hence contributing to a perceived improvement in animal welfare. The CRISPR/Cas9 technology was used to edit either exon 2 or exon 5 of the pig AR gene. Although pregnancies were established following embryo transfer of edited embryos, they were not maintained beyond day 25. Furthermore, normal M:F sex ratios were present in edited blastocysts and 19-day fetuses, but all fetuses recovered on day 21 or later were female. The pig AR gene differs from the mouse in having a U2 spliceosome component encoded in the intronic region. Hence, the absence of fetal survival beyond day 25 may be due to interference with the U2 component rather than AR.

Costs and consequences of cellular compartmentalization and substrate competition among human enzymes involved in androgen and estrogen synthesis.

The impact of compartmental expression of steroidogenic enzymes and of changes in flux through delta5 and delta4 metabolism on sex steroid synthesis was investigated by rebuilding pathways using recombinant enzyme expression by infection of insect cells with recombinant baculovirus constructs. Human cytochromes 17alpha-hydroxylase/17,20-lyase (P450c17) and aromatase (P450arom), always coexpressed with their redox partner NADPH-P450 oxidoreductase (CPR) and 3beta-hydroxysteroid dehydrogenase/delta5-4 isomerase (3betaHSD; types 1 or 2), were compartmentally expressed in different cell populations or coexpressed together with pregnenolone (100 nM) as substrate. Estrone was compared among cell compartments expressing different enzyme combinations or in cells coexpressing all enzymes (experiment 1). Additionally, P450c17, 3betaHSD, and CPR were all coexpressed, and androstenedione was measured in cells with different 3betaHSD expression levels or activity using an inhibitor, trilostane (experiment 2). Steroids were measured by immunoassay and mass spectrometry. In experiment 1, partitioning of P450c17, P450arom, and 3betaHSD markedly decreased estrone synthesis in comparison to cells coexpressing enzymes in different combinations. However, partitioning P450arom with 3betaHSD from P450c17 in different cell populations resulted in more estrone than either of the other two-cell compartment models. In experiment 2 (cells coexpressing P450c17, 3betaHSD, and CPR), androstenedione secretion was (paradoxically) higher at lower levels of 3betaHSD, and partial inhibition of 3betaHSD by trilostane also increased androstenedione when 3betaHSD expression was high. We conclude 1) that tissue or cell-specific, partitioned expression of sex steroid synthesizing enzymes limits rather than maximizes estrogen synthesis and 2) that limiting metabolism by 3betaHSD can paradoxically promote androgen synthesis when 3betaHSD expression is high by promoting delta5-steroid flux.

Stimulation of Sertoli cell proliferation: defining the response interval to an inhibitor of estrogen synthesis in the boar.

Sertoli cell proliferation occurs in two major waves after birth, one neonatally and another prepubertally, each contributing to final testicular size and sperm production. However, little is known about the regulation of either wave. We have previously shown that letrozole, an inhibitor of estrogen synthesis, increases Sertoli cell number and testicular size at sexual maturity in boars. These studies were conducted to determine whether letrozole affects the first or second proliferative wave. Boars were treated with letrozole during the first wave (treatment at 1, 3, and 5 weeks), less frequently (1 week of age only, or 1 and 5 weeks), on postnatal day 1, or during the second wave (weeks 11-16). Sertoli cells were enumerated in testes and estrogen concentrations were evaluated in serum and testes. Compared with vehicle controls, letrozole reduced estrogen in boars treated at weeks 1 and 5 or 1, 3, and 5, on postnatal day 1, or prepubertally. However, Sertoli cell numbers were increased only in boars treated at 1, 3, and 5 weeks of age. Neither perinatal (1 day old) nor prepubertal letrozole treatment affected Sertoli cell numbers. Hence, Sertoli cell proliferation was sensitive to letrozole only if letrozole was administered throughout the first wave, even though estrogen synthesis was effectively inhibited at all ages. These data indicate that the neonatal but not the prepubertal window of Sertoli cell proliferation is sensitive to an inhibitor of estrogen synthesis; this suggests that these two waves are differently regulated.

Expression of CSF1, AR, and SRD5A2 during Postnatal Development of the Boar Reproductive Tract.

The male reproductive system develops from a minimally functioning gonad and nonfunctioning accessory sex glands in the neonate; sex steroids, presumed to be primary influencers of these changes, have been characterized in multiple species. This study focused on the expression of the androgen receptor as the principal mediator of androgen-induced signaling; the 5α reductase enzyme that converts testosterone to the more active dihydrotestosterone; and colony stimulating factor 1, a mediator of macrophage influence on organ development in the pig. The time points chosen to evaluate normal developmental changes during the juvenile and prepubertal intervals included the inflection time points of 6.5 weeks of age at the nadir of circulating estradiol and testosterone concentrations in juveniles, and 11 weeks of age, when these concentrations begin to increase. The role of sex steroid signaling in the regulation of gene expression was evaluated by the blockade of androgen and estrogen receptors and reduction in endogenous estrogens. Expression of colony stimulating factor 1 in the testes gradually decreased during development; developmental profiles in the prostate and seminal vesicles were clearly different. Interference with sex steroid signaling had no effect on the expression of these three genes in testicular tissue and minimal and transient effects in prostate and seminal vesicles.

Multifaceted epigenetic regulation of porcine testicular aromatase.

Testicular aromatase catalyzes the synthesis of estradiol, which contributes to regulation of porcine Sertoli cell proliferation and postpubertal maintenance of Sertoli cell numbers. Although aromatase enzymatic activity decreases with age and is persistently reprogrammed by prepubertal treatment with the aromatase inhibitor letrozole, the molecular bases for regulation have not been identified. DNA methylation was examined as a potential regulatory mechanism using DNA from Leydig cells isolated from 16-, 40-, and 68-week-old boars and from 68- week-old littermates treated with the aromatase inhibitor, letrozole. Methylation levels of individual CpG dinucleotides located in the distal untranslated exon 1 of the relevant aromatase encoding gene, CYP19A3, were quite high in Leydig cell DNA, and increased further with maturity of boar (P < 0.05), while aromatase activity and transcript abundance decreased more than two-fold. However, reduced aromatase activity following letrozole treatment was not accompanied by altered DNA methylation. Testicular expression of miR378 was altered by prepubertal treatment with letrozole. The data provide evidence for two different epigenetic mechanisms that regulate aromatase expression and enzymatic activity in the boar testis.

Genomic Structure of the Porcine CYP19 Locus and Expression of the CYP19A3 Paralog.

Proper, tissue-specific regulation of CYP19, the gene encoding aromatase, the key enzyme of estrogen synthesis, is essential for reproductive processes. Here, we analyzed transcriptional regulation of the porcine CYP19 in female and male gonads and brain by 5'RACE and RT-PCR and comprehensively mapped the pig CYP19 locus by in silico analysis. Our data revealed that the complete locus, including three paralogous copies, CYP19A1, CYP19A2 and CYP19A3, spans approximately 330 kb of the porcine chromosome 1. The locus also harbors the first exon of the Gliomedin gene (GLDN) in reverse orientation. Only transcripts of the CYP19A3 paralog were substantially expressed in gonads and hypothalamus. We identified CYP19A3-associated untranslated exons approximately 160 kb and 50 kb distal from the first codon. The 5´ untranslated regions of transcripts were derived from either a proximal or from one of these distal untranslated exons. Transcripts including only untranslated exons could be amplified from testis, thus suggesting long non-coding transcripts. The data revealed an additional layer of complexity in the regulation of the porcine CYP19 locus. Tissue-specific expression is not only achieved by tissue- and stage-specific expression of the three different CYP19 paralogs, but also by directing the expression of CYP19A3 from different, proximal and distal promoter regions.

Changes in testicular gene expression following reduced estradiol synthesis: A complex pathway to increased porcine Sertoli cell proliferation.

Porcine Sertoli cell number including number present at puberty is increased if testicular estradiol synthesis is reduced during the neonatal interval. Evaluating the changes in gene expression during the crucial interval of suppressed estradiol that leads to the increased Sertoli cell population will increase our understanding of Sertoli cell biology but this evaluation first required a more precise determination of the critical interval for treatment and timing of a detectable response. Previously, reduced testicular estrogens from 1 week of age were accompanied by increased Sertoli cell number at 6.5 weeks of age but the age at which Sertoli cell numbers were initially increased was unknown, one of the current objectives. Additional experiments were designed to further delineate the essential timing of treatment for the Sertoli cell response. Finally, changes in gene expression induced by the reduced estradiol synthesis were evaluated to elucidate molecular mechanisms. Experimental design typically consisted of one member of littermate pairs of boars treated with the aromatase inhibitor, letrozole, beginning at 1 week of age and the remaining member treated with canola oil vehicle. Weekly treatments continued through 5 weeks of age or tissue collection, whichever came first. Increases in Sertoli cell numbers were not detectable prior to 6.5 weeks of age and persistent treatment through 5 weeks of age was required to induce the increase in Sertoli cell numbers. This increase resulted from prolonging the first interval of Sertoli cell proliferation in the treated animals. Few genes exhibited dramatically altered transcription and similarities in pathway analysis or principal modified genes were quite limited in 2, 3, and 5-week-old boars. The critical timing and prolonged treatment required and the sequential changes in gene expression suggest a complex mechanism is involved in this model of increased proliferation of Sertoli cells.

Effects of chronic intranasal oxytocin on behavior and cerebral glucose uptake in juvenile titi monkeys.

Intranasal oxytocin (IN OXT) has been proposed as a treatment for autism spectrum disorder (ASD); however, little is known about the effects of long-term exposure. This is the first study in a non-human primate species to examine how developmental exposure to chronic IN OXT affects juvenile's interactions with family members, social preference for parents versus strangers, anxiety-like behavior, and cerebral glucose metabolism. Titi monkeys are socially monogamous and biparental; their family bonds share important characteristics with human family bonds. Fourteen males and 15 females were treated intranasally with saline (n = 14) or 0.8 IU/kg OXT (n = 15), daily from 12 to 18 months of age. Compared to SAL-treated animals, OXT-treated animals of both sexes spent significantly more time grooming other family members (F1 = 8.97, p = 0.006). Overall, OXT-treated subjects were more social (F1 = 8.35, p = 0.005) during preference tests. OXT-treated females displayed an enhanced preference for their parents (t = 2.265, p = 0.026). OXT-treated males had a blunted preference for their parents and an increase in the time spent near unfamiliar pairs (F1 = 10.89, p = 0.001). During anxiety tests, OXT-treated males refused to complete the task more often than SAL-treated males and had longer latencies (p < 0.0001). Neuroimaging studies revealed that OXT-treated animals had higher glucose uptake across the social salience network as a whole after one month of treatment (F1,9 = 1.07, p = 0.042). Our results suggest moderate prosocial effects of chronic IN OXT, that did not depend on anxiolytic properties. We also found important sex differences that should be considered in a translational context.

Testicular estradiol and the pattern of Sertoli cell proliferation in prepuberal bulls.

Sertoli cells nourish developing sperm with the number of Sertoli cells being a major determinant of sperm production capacity in a male. The objectives of these studies were to numerically characterize the prepuberal populations of bovine Sertoli cells to determine the pattern of proliferation and to determine if the prepuberal population could be expanded by reducing endogenous testicular estrogens. Groups of Angus-Hereford crossbred bull calves were castrated at 0.25 mo (n = 6) and 1, 2, 3, 4, 5, or 6 mo of age (n = 8 per age). Testes were weighed and equatorial slices fixed. Sertoli cell density was determined following labeling of Sertoli cells with GATA-4 antibody in 30-µm thick sections. The number of Sertoli cells per testis increased linearly from 0.25 mo to 5 mo of age. Sertoli cell numbers appeared to plateau at 5 mo of age with luminal development present at that age. Only a single postnatal wave of Sertoli cell proliferation was detectable in the bull. To evaluate the regulatory role of testicular estrogens, Jersey bull caves were treated twice weekly with the aromatase inhibitor, letrozole, from 2 to 22 wk of age and control animals were treated with the canola oil vehicle. Testes were retrieved at 26 wk of age. Testes were weighed and Sertoli cell density was subsequently determined. Estradiol was lower in testicular tissue from letrozole-treated bulls as expected (P < 0.001). Inhibition of aromatase had no effect on testosterone or circulating LH; testosterone increased with age as expected. Inhibition of aromatase and consequent reduced testicular estradiol did not alter Sertoli cell numbers.