The influence of psychological stress in early life on sexual maturation and sexual behavior in male and female rats

Depletion of Fkbp5 Protects Against the Rapid Decline in Ovarian Reserve Induced by Prenatal Stress in Female Offspring of Wild-Type Mice

Prenatal stress (PNS) impairs offspring ovarian development by exerting negative long-term effects on postnatal ovarian function and folliculogenesis. FKBP51 is a stress-responsive protein that inhibits glucocorticoid and progesterone receptors. We hypothesize that FKBP51 contributes to impaired ovarian development and folliculogenesis induced by PNS. Timed-pregnant Fkbp5+/+ (wild-type) and Fkbp5-/- (knockout) mice were randomly assigned to either the undisturbed (nonstress) or PNS group, with exposure to maternal restraint stress from embryonic days 8 to 18. Ovaries from the offspring were harvested and stained, and follicles were counted according to their stages. Ovarian expressions of FKBP51 were evaluated by immunohistochemistry and Fkbp5 and steroidogenic enzymes were evaluated by qPCR. Compared to controls, Fkbp5+/+ PNS offspring had increased peripubertal primordial follicle atresia and fewer total follicles in the adult and middle-aged groups. In adult Fkbp5+/+ offspring, PNS elevated FKBP51 levels in granulosa cells of primary to tertiary follicles. Our results suggest that PNS administration increased FKBP51 levels, depleted the ovarian reserve, and dysregulated ovarian steroid synthesis. However, these PNS effects were tolerated in Fkbp5-/- mice, supporting the conclusion that FKBP51 contributes to reduced ovarian reserve induced by PNS.

Inflammation and oxidative stress processes in induced precocious puberty in rats

This study aimed to assess the influence of different types of blue light sources on male and female rats' puberty onset, the morphologic-induced alterations in reproductive organs tissues, the impact on inflammation and oxidative stress markers, anxiety levels, and mathematical modeling for tissue data interpretation. Four groups of sixteen rats each (8 females and 8 males/group) were investigated: three groups were exposed to blue light from mobile phones (MP), computer screens (PC), or LED lamps (LED) versus the control group (CTRL). The rats in the CTRL group had no exposure while the other groups were exposed for 30 days to the blue light of MP, PC, and LED for 16 h per day. Serum levels of cortisol, TNF-α, IL-6, and MMP-2 and MMP-9 ovaries and testis tissue levels were analyzed using the ELISA technique. Total oxidative stress (TOS), nitric oxide (NO), and malondialdehyde (MDA) in serum were determined spectrophotometrically. Histomorphological examination was performed on both male and female genital organs. Rats of both sexes presented significant early onset of puberty secondary to blue light exposure. LED-emitted light significantly increased TNF-α and MMP-9 levels in both sexes. The MP and PC emitted light significantly affected the levels of MMP-2 in both females and males. Levels of TOS and NO were increased by LED, respectively by MP and LED exposure in female rats. The histopathological examination revealed no statistically significant differences in the ovaries and testes of rats across the different groups. Blue light exposure induces precocious puberty, by accelerating sexual maturation, and triggers the overproduction of MMPs that could promote organic alteration through tissue remodeling. Oxidative stress parameters were upregulated only in female rats, while cortisol levels were higher in male rats.

Effects of double neonatal stress on female rat sexual behaviour

Neonatal stress affects psychological and physiological development and may be associated with affective disorders. The aim was to examine the effects of double neonatal stress (DNS) - a combination of limited bedding and nesting (LBN) and repeated maternal separation (MS) - on the oestrous cycle and sexual behaviour of adult female rats. LBN was achieved by removing part of the wood shavings from the boxes. In the control group, each box was lined with 100 g of wood shavings, while in the experimental group there were only 10 g of wood shavings. MS was performed from P1 (P0 = day of birth) to P15. At P90, the sexual response of females in oestrus was evaluated. Statistical analysis was performed using two-way analysis of variance followed by Tukey's test. The size and profile of the oestrous cycle and the sexual behaviour of female rats submitted to the DNS were considered, as well as the influence of female behaviour on the sexual response of male rats. Female rats submitted to DNS showed a reduction in the lordosis quotient, suggesting a reduction in female receptivity. These rats also showed a reduction in the number of hops and darts, the number of ear wiggles, and the genital exploration time rate, suggesting a reduction in proceptivity. The males that interacted with the females of the DNS group showed a reduction in intromission ratio. Experimental model that mimics neonatal factors that affect adult female sexual response will allow more effective interventions to prevent and treat such changes. In addition, analysis of the female sexual response makes it possible to assess the general state of health and quality of life. In female rats, DNS exerted inhibitory effects on sexual behaviour. LBN was probably the most important factor. In conclusion, combating childhood poverty can be a key measure to prevent problems in the sex life of adults and improve overall health.

Effects of social environments on male primate HPG and HPA axis developmental programming

Developmental plasticity is particularly important for humans and other primates because of our extended period of growth and maturation, during which our phenotypes adaptively respond to environmental cues. The hypothalamus-pituitary-gonadal (HPG) and hypothalamus-pituitary-adrenal (HPA) axes are likely to be principal targets of developmental "programming" given their roles in coordinating fitness-relevant aspects of the phenotype, including sexual development, adult reproductive and social strategies, and internal responses to the external environment. In social animals, including humans, the social environment is believed to be an important source of cues to which these axes may adaptively respond. The effects of early social environments on the HPA axis have been widely studied in humans, and to some extent, in other primates, but there are still major gaps in knowledge specifically relating to males. There has also been relatively little research examining the role that social environments play in developmental programming of the HPG axis or the HPA/HPG interface, and what does exist disproportionately focuses on females. These topics are likely understudied in males in part due to the difficulty of identifying developmental milestones in males relative to females and the general quiescence of the HPG axis prior to maturation. However, there are clear indicators that early life social environments matter for both sexes. In this review, we examine what is known about the impact of social environments on HPG and HPA axis programming during male development in humans and nonhuman primates, including the role that epigenetic mechanisms may play in this programming. We conclude by highlighting important next steps in this research area.

Postweaning Social Isolation Alters Puberty Onset by Suppressing Electrical Activity of Arcuate Kisspeptin Neurons

INTRODUCTION

Postweaning social isolation (PWSI) in rodents is an advanced psychosocial stress model in early life. Some psychosocial stress, such as restrain and isolation, disrupts reproductive physiology in young and adult periods. Mechanisms of early-life stress effects on central regulation of reproduction need to be elucidated. We have investigated the effects of PWSI on function of arcuate kisspeptin (ARCKISS1) neurons by using electrophysiological techniques combining with monitoring of puberty onset and estrous cycle in male and female Kiss1-Cre mice.

METHODS

Female mice were monitored for puberty onset with vaginal opening examination during social isolation. After isolation, the estrous cycle of female mice was monitored with vaginal cytology. Anxiety-like behavior of mice was determined by an elevated plus maze test. Effects of PWSI on electrophysiology of ARCKISS1 neurons were investigated by the patch clamp method after intracranial injection of AAV-GFP virus into arcuate nucleus of Kiss1-Cre mice after the isolation period.

RESULTS

We found that both male and female isolated mice showed anxiety-like behavior. PWSI caused delay in vaginal opening and extension in estrous cycle length. Spontaneous-firing rates of ARCKISS1 neurons were significantly lower in the isolated male and female mice. The peak amplitude of inhibitory postsynaptic currents to ARCKISS1 neurons was higher in the isolated mice, while frequency of excitatory postsynaptic currents was higher in group-housed mice.

CONCLUSION

These findings demonstrate that PWSI alters pre- and postpubertal reproductive physiology through metabolic and electrophysiological pathways.

L-Arginine abrogates maternal and pre-pubertal codeine exposure-induced impaired spermatogenesis and sperm quality by modulating the levels of mRNA encoding spermatogenic genes

INTRODUCTION

Although, codeine has been demonstrated to lower sperm quality; the effects of maternal and prepubertal codeine exposure on male offspring is yet to be reported. In addition, the effect of arginine on codeine-induced decline in sperm quality has not been explored. This study investigated the impact of maternal and prepubertal codeine exposure on spermatogenesis and sperm quality in F1 male Wistar rats to study the effect that codeine may have during recreational use in humans. Also, the effect of arginine supplementation on codeine-induced alteration in spermatogenesis and sperm quality was evaluated.

METHODS

Female rats were treated with either 0.5 ml distilled water or codeine orally for eight weeks, and then mated with male rats (female:male, 2:1). The F1 male offsprings of both cohorts were weaned at 3 weeks old and administered distilled water, codeine, arginine, or codeine with arginine orally for eight weeks.

RESULTS

Prepubertal codeine exposure in rats whose dams (female parents) were exposed to codeine delayed puberty and reduced the weight at puberty. Prepubertal codeine exposure exacerbated maternal codeine exposure-induced reduced total and daily spermatid production, sperm count, sperm motility, and normal sperm form, as well as impaired sperm plasma membrane integrity and increased not intact acrosome and damaged sperm DNA integrity. These perturbations were accompanied by a decrease in mRNA levels encoding spermatogenic genes, testicular testosterone and androgen receptor (AR) concentrations, and upregulation of sperm 8-hydroxydeoxyguanosine (8OHdG). Prepubertal arginine supplementation mitigated codeine-induced alterations.

DISCUSSION

This study provides novel experimental evidence that maternal and prepubertal codeine exposure reprogramed spermatogenesis and sperm quality of male FI generation by decreasing mRNA levels encoding spermatogenic genes and AR via oxidative stress-mediated signaling, which was abrogated by prepubertal arginine supplementation.

Preterm pigs for preterm birth research: reasonably feasible

Preterm birth will disrupt the pattern and course of organ development, which may result in morbidity and mortality of newborn infants. Large animal models are crucial resources for developing novel, credible, and effective treatments for preterm infants. This review summarizes the classification, definition, and prevalence of preterm birth, and analyzes the relationship between the predicted animal days and one human year in the most widely used animal models (mice, rats, rabbits, sheep, and pigs) for preterm birth studies. After that, the physiological characteristics of preterm pig models at different gestational ages are described in more detail, including birth weight, body temperature, brain development, cardiovascular system development, respiratory, digestive, and immune system development, kidney development, and blood constituents. Studies on postnatal development and adaptation of preterm pig models of different gestational ages will help to determine the physiological basis for survival and development of very preterm, middle preterm, and late preterm newborns, and will also aid in the study and accurate optimization of feeding conditions, diet- or drug-related interventions for preterm neonates. Finally, this review summarizes several accepted pediatric applications of preterm pig models in nutritional fortification, necrotizing enterocolitis, neonatal encephalopathy and hypothermia intervention, mechanical ventilation, and oxygen therapy for preterm infants.

Sex differences in addiction-relevant behavioral outcomes in rodents following early life stress

In humans, exposure to early life stress (ELS) is an established risk factor for the development of substance use disorders (SUDs) during later life. Similarly, rodents exposed to ELS involving disrupted mother-infant interactions, such as maternal separation (MS) or adverse caregiving due to scarcity-adversity induced by limited bedding and nesting (LBN) conditions, also exhibit long-term alterations in alcohol and drug consumption. In both humans and rodents, there is a range of addiction-related behaviors that are associated with drug use and even predictive of subsequent SUDs. In rodents, these include increased anxiety-like behavior, impulsivity, and novelty-seeking, altered alcohol and drug intake patterns, as well as disrupted reward-related processes involving consummatory and social behaviors. Importantly, the expression of these behaviors often varies throughout the lifespan. Moreover, preclinical studies suggest that sex differences play a role in how exposure to ELS impacts reward and addiction-related phenotypes as well as underlying brain reward circuitry. Here, addiction-relevant behavioral outcomes and mesolimbic dopamine (DA) dysfunction resulting from ELS in the form of MS and LBN are discussed with a focus on age- and sex-dependent effects. Overall, these findings suggest that ELS may increase susceptibility for later life drug use and SUDs by interfering with the normal maturation of reward-related brain and behavioral function.