The reduction in sexual behavior induced by neonatal immune stress is not related to androgen levels in male rats

Early Life Painful Procedures: Long-Term Consequences and Implications for Farm Animal Welfare

Farm animals routinely undergo painful husbandry procedures early in life, including disbudding and castration in calves and goat kids, tail docking and castration in piglets and lambs, and beak trimming in chicks. In rodents, inflammatory events soon after birth, when physiological systems are developing and sensitive to perturbation, can profoundly alter phenotypic outcomes later in life. This review summarizes the current state of research on long-term phenotypic consequences of neonatal painful procedures in rodents and farm animals, and discusses the implications for farm animal welfare. Rodents exposed to early life inflammation show a hypo-/hyper-responsive profile to pain-, fear-, and anxiety-inducing stimuli, manifesting as an initial attenuation in responses that transitions into hyperresponsivity with increasing age or cumulative stress. Neonatal inflammation also predisposes rodents to cognitive, social, and reproductive deficits, and there is some evidence that adverse effects may be passed to offspring. The outcomes of neonatal inflammation are modulated by injury etiology, age at the time of injury and time of testing, sex, pain management, and rearing environment. Equivalent research examining long-term phenotypic consequences of early life painful procedures in farm animals is greatly lacking, despite obvious implications for welfare and performance. Improved understanding of how these procedures shape phenotypes will inform efforts to mitigate negative outcomes through reduction, replacement, and refinement of current practices.

A review of the pathophysiology of functional hypothalamic amenorrhoea in women subject to psychological stress, disordered eating, excessive exercise or a combination of these factors

INTRODUCTION

Functional hypothalamic amenorrhoea (FHA) is a common form of secondary amenorrhoea without an identifiable structural cause. Suppression of gonadotrophin-releasing hormone (GnRH) pulsatility results in reduced luteinizing hormone (LH) levels, with subsequent reduction in oestradiol, anovulation and cessation of menstruation. GnRH pulsatility suppression is a recognized complication of psychological stress, disordered eating, low body weight, excessive exercise or a combination of these factors.

PATHOPHYSIOLOGY OF FHA

Individuals with FHA demonstrate low energy availability (EA), body fat percentage and energy expenditure. Documented adipocytokine changes notably, raised adiponectin, ghrelin, PYY, and decreased leptin, are associated with GnRH suppression. Other endocrine responses seen in this low EA state include low insulin levels, low total T3, increased basal cortisol levels and a reduced response to corticotrophin-releasing hormone (CRH) administration. FHA is associated with raised growth hormone (GH) and low insulin-like growth factor (IGF-1), suggesting relative GH resistance. Kisspeptins are a group of polypeptides, recently discovered to play a major role in the regulation of the reproductive axis through influencing GnRH release. KNDy (kisspeptin/neurokinin B/dynorphin) act on GnRH neurons and a multitude of factors result in their release.

IMPLICATIONS FOR FUTURE TREATMENT

Management of FHA is imperative to prevent adverse outcomes in bone density, cardiovascular risk profile, psychological well-being and fertility. Outwith modification of nutritional intake and exercise, limited therapeutic strategies are currently available for women with FHA. Advancements in the understanding of the pathophysiological basis of this under-recognized and under-treated clinical entity will aid management and may result in the development of novel therapeutic approaches.

Characterization of fever and sickness behavior regulated by cytokines during infection

In response to invasion of pathogens, hosts present fever and a series of behavioural changes including reduced grooming, reduction of foraging, decreased locomotion, withdrawing from social activities and reproductive process, which are collectively termed sickness behaviour. Fever as well as sickness behaviour are adaptive and benefit the host to reduce pathology caused by infections and opportunity costs for time away from foraging, reproduction and predator avoidance. Antipathogenic fever and sickness behaviour are mediated proximately by cytokines including pro- and anti-inflammatory cytokines. Pro-inflammation cytokines trigger these sickness responses, while anti-inflammatory cytokines constrain these responses and prevent damage to host from exaggerated responses. The present study reviews the characterization of fever and sickness behaviour regulated by cytokines during infection.

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

PURPOSE

We studied the influence of psychological stress during the early neonatal period on sexual maturation and sexual behavior in rats.

METHODS

Neonatal male and female rats were divided into control (C) and maternal separation (MS) groups (n = 20-24 per group). The pups in the MS groups were placed in isolation cages for 240 minutes/d from postnatal days 2-11. Vaginal opening (VO) in females and preputial separation (PS) in males (indicators of sexual maturation) were monitored, as was the estrous cycle in females. Thereafter, sexual behavior was monitored twice at 13 and 15 weeks of age.

RESULTS

As for sexual maturation, the onset of PS occurred significantly earlier in the MS group than in the C group, whereas the onset of VO did not differ between the groups. The length of the estrous cycle did not differ between the groups. The frequencies of sexual behaviors did not differ between the groups in either sex.

CONCLUSIONS

In conclusion, early-life psychological stress induced by MS advanced sexual maturation in male rats, whereas it did not affect sexual maturation in female rats. On the other hand, early-life psychological stress might not affect sexual behavior in adulthood in either sex.

The reduction in sexual behavior of adult female rats exposed to immune stress in the neonatal period is associated with reduced hypothalamic progesterone receptor expression

PURPOSE

We examined the mechanism by which neonatal immune stress reduces the sexual behavior of female rats in adulthood.

METHODS

Neonatal female rats were randomly divided into 3 groups: control (n = 11), postnatal day 10 lipopolysaccharide (PND10LPS) (n = 23), and PND25LPS (n = 11) groups, which received intraperitoneal injections of LPS (100 μg/kg) or saline on PND10 and 25. Daily inspections of the vaginal opening (VO) were performed from PND27 to PND37. Thereafter, the frequency of estrus was assessed for 15 days. Female rats (at 11-12 weeks of age) were placed in a cage with male rats, and their sexual behavior was monitored for 30 min. The hypothalamic mRNA expression levels of factors related to sexual behavior were examined via real-time PCR.

RESULTS

VO occurred later and the frequency of estrus was lower in the PND10LPS group compared to the control group. The number of lordosis behaviors and the total number of mounts performed by male partners were lower in the PND10LPS and PND25LPS groups than in the control group. Acceptability: The lordosis quotient and lordosis rating were lower in the PND10LPS group than in the control group. Proceptive behavior: the number of ear wiggling events was lower in the PND10LPS group than in the other groups, and the number of hops/darts was lower in the PND10LPS group than in the control group. The hypothalamic mRNA expression level of progesterone receptors (PR)A + B was lower in the PND10LPS group than in the control group, and the hypothalamic PRB mRNA expression level was lower in the PND10LPS and PND25LPS groups than in the control group.

CONCLUSION

Neonatal immune stress impeded sexual behavior and hypothalamic PR mRNA expression in female rats. Decreased progesterone activity in the hypothalamus might explain the reduction in sexual behavior seen in these rats.