Pubertal Stress In Male Rats: Effects on Juvenile Play Behavior and Adult Sexual Partner Preference

Puberty is a period of brain organization impacting the expression of social and sexual behaviors. Here, we assessed the effects of an acute pubertal stressor (immune challenge) on the expression of juvenile play (short-term) and sexual partner preference (long-term) in male rats. Juvenile play was assessed over ten trials at postnatal days (PND) (31-40) with age- and sex-matched conspecifics, and at PND35 males received a single injection of lipopolysaccharide (LPS, 1.5 mg/kg i.p.) or saline. Then, sexual partner preference was assessed at PND 60, 64, and 68, in a three-compartment chamber with a sexually receptive female and a male as potential partners simultaneously. The results confirmed that a single injection of LPS during puberty induced sickness signs indicative of an immune challenge. However, juvenile play was not affected by LPS treatment during the following days (PND36-40), nor was sexual behavior and partner preference for females in adulthood. These findings highlight that, while other studies have shown that LPS-induced immunological stress during puberty affects behavior and neuroendocrine responses, it does not affect juvenile play and sexual behavior in male rats. This suggests a remarkable resilience of these behavioral systems for adaptation to stressful experiences mediated by immune challenges during critical periods of development. These behaviors, however, might be affected by other types of stress.

Hyperbaric oxygen preconditioning normalizes scrotal temperature, sperm quality, testicular structure, and erectile function in adult male rats subjected to exertional heat injury

Testicular hyperthermia has been noted in men who work in high ambient temperatures. Scrotal temperatures above the normal range caused germ cell loss in the testes and resulted in male subfertility. In adult male rats, exercising at a higher environmental temperature (36 °C with relative humidity of 50%, 52 min) caused exertional heat stroke (EHS) characterized by scrotal hyperthermia, impaired sperm quality, dysmorphology in testes, prostates and bladders, and erectile dysfunction. Here, we aim to ascertain whether hyperbaric oxygen preconditioning (HBOP: 100% O2 at 2.0 atm absolute [ATA] for 2 h daily for 14 days consequently before the onset of EHS) is able to prevent the problem of EHS-induced sterility, testes, prostates, and bladders dysmorphology and erectile dysfunction. At the end of exertional heat stress compared to normobaric air (NBA or non-HBOP) rats, the HBOP rats exhibited lower body core temperature (40 °C vs. 43 °C), lower scrotal temperature (34 °C vs. 36 °C), lower neurological severity scores (2.8 vs. 5.8), higher erectile ability, (5984 mmHg-sec vs. 3788 mmHg-sec), higher plasma testosterone (6.8 ng/mL vs. 3.5 ng/mL), lower plasma follicle stimulating hormone (196.3 mIU/mL vs. 513.8 mIU/mL), lower plasma luteinizing hormone (131 IU/L vs. 189 IU/L), lower plasma adrenocorticotropic hormone (5136 pg/mL vs. 6129 pg/mL), lower plasma corticosterone (0.56 ng/mL vs. 1.18 ng/mL), lower sperm loss and lower values of histopathological scores for epididymis, testis, seminal vesicle, prostate, and bladder. Our data suggest that HBOP reduces body core and scrotal hyperthermia and improves sperm loss, testis/prostate/bladder dysmorphology, and erectile dysfunction after EHS in rats.

OUP accepted manuscript

Objective

The central objective of this study was to investigate the cumulative effects restraint stress and sodium arsenite on reproductive health in male rats.

Methods

Healthy male Wistar rats were allocated into 4 groups (n = 8). Animals in group 1 served as controls and did not subjected to any stress. Rats in groups 2, 3, and 4 were subjected to either restraint stress (5 h/day) or maintained on arsenic (25 ppm) via drinking water or both for 65 days. After completion of the experimental period, all the rats were analyzed for selected reproductive endpoints.

Results

Restraint stress or sodium arsenite treatment increased serum corticosterone levels, reduced testicular daily sperm count, epididymal sperm viability, motility, membrane integrity, and decreased testicular steroidogenic enzymes such as 3β- and 17β-hydroxysteroid dehydrogenases associated with reduced serum testosterone levels, deteriorated testicular architecture, and reduced activity levels of testicular superoxide dismutase and catalase accompanied by elevated lipid peroxidation levels. In rats subjected to restraint stress and sodium arsenite, a significant decrease in selected sperm qualitative and quantitative parameters, serum testosterone levels were observed as compared with rats subjected to sodium arsenite alone. A significant increase in the levels of lipid peroxidation with a concomitant decrease in the activities of antioxidant enzymes was observed in the testis of rats subjected to both restraint stress and sodium arsenite treatment as compared with sodium arsenite alone intoxicated rats. Surprisingly, serum corticosterone levels were significantly elevated in rats following both stressors as compared with arsenic alone treated rats. Analysis of atomic absorption spectroscopy revealed that the accumulation of arsenic in the testis of arsenic-treated and arsenic plus immobilization stress groups was significant as compared with controls.

Conclusions

Based on the findings, it can be concluded that deterioration of male reproductive health could be accelerated in arsenic intoxicated rats following restraint stress.

Chronic stress impairs male spermatogenesis function and nectin-3 protein expression in the testis

Chronic stress is a crucial public issue that occurs when a person is repetitively stimulated by various stressors. Previous researches have reported that chronic stress induces spermatogenesis dysfunction in the reproductive system, but its molecular mechanisms remain unclear. The nectin protein family, including nectin-1 to nectin-4, is Ca(2+)-independent immunoglobulin-like cell adhesion molecules, that are widely expressed in the hippocampus, testicular tissue, epithelial cells and other sites. Nectin-3 contributes to the sperm development at the late stage, and the abnormal expression of nectin-3 impairs spermatogenesis. Some recent studies have demonstrated that stress induces a decrease in nectin-3 expression in the hippocampus via corticotropin-releasing hormone (CRH) to corticotropin-releasing hormone receptor 1 (CRHR1) pathway. Here, we tested whether chronic stress also caused a reduction in nectin-3 expression in the testis. We established a chronic social defeat stress paradigm, which provides naturalistic and complex chronic stress in male C57BL/6 mice. After 25 days of chronic social defeat stress, the mice showed weight loss, thymic atrophy and some other typical symptoms of chronic stress (e.g. anxiety-like behavior and social avoidance behavior). We found gonad atrophy, testicular histological structure changes and semen quality reductions in the stressed mice. The stressed male mice significantly spent more time to impregnate the female mice than the control male mice. Moreover, nectin-3 protein levels in stressed mice were significantly decreased in the testes compared with those in control mice. In addition, we found that the CRHR1 expression level was increased in the testes of stressed mice. Therefore, we demonstrated a decreased level of nectin-3 expression and an increase in CRHR1 expression in the testis after exposure to chronic stress, which may provide a potential therapeutic target for the spermatogenesis dysfunction induced by chronic stress.

Resveratrol Ameliorates Testicular Histopathology of Mice Exposed to Restraint Stress

Simple Summary

The search for effective medicines is challenging. Resveratrol is a phytoalexin, and its function remains unelucidated. Therefore, we undertook the present study to investigate reproductive disturbances due to restraint stress in mice and whether resveratrol plays an anti-stress role. Our results confirmed that resveratrol plays a potential role in the reduction of stress in mice.

Abstract

We evaluated immobilization stress and resveratrol supplementation in immature male mice at 30 days of age for 15 consecutive days. Fifty Swiss mice were divided into five groups (10 mice each): Controls, restraint stress (RS), restraint stress + vehicle (RS + V), RS + 2 mg/kg, and RS + 20 mg/kg. We determined results on the basis of hematoxylin and eosin (H&E), “Periodic acid-Schiff” staining, and TUNEL assay. The results indicated that immobilization stress significantly decreased body weight, testis weight, and water/food intake compared to the control; while resveratrol ameliorated these effects. The quantitative histologic evaluation of the seminiferous tubule diameter, luminal diameter, area of seminiferous tubules, area of tubule lumen, epithelial height, Leydig cell number, and the width of the tunica albuginea were similarly decreased after exposure to RS. These parameters recovered back to normal in the RS + 2 mg/kg group. The development of spermatogenesis was significantly delayed in the RS, RS + V, and RS + 20 mg groups based upon our evaluation score system. However, we observed no significant differences in the RS + 2 mg group compared with the control group. The number of TUNEL-positive cells also significantly decreased in the RS + 2 mg/kg group. In conclusion, we found that the administration of 2 mg/kg was an effective dose against immobilization stress in mice.

Polygamy and Risk of Coronary Artery Disease in Men Undergoing Angiography: An Observational Study

Epidemiologic evidence suggests a link between psychosocial risk factors such as marital status and coronary artery disease (CAD). Polygamy (multiple concurrent wives) is a distinct marital status practiced in many countries in Asia and the Middle East, but its association with CAD is not well defined. We conducted a multicenter, observational study of consecutive patients undergoing coronary angiography during the period from April 1, 2013, to March 30, 2014. Of 1,068 enrolled patients, 687 were married men. Polygamy was reported in 32% of married men (1 wife: 68%, 2 wives: 19%, 3 wives: 10%, and 4 wives: 3%). When stratified by number of wives, significant baseline differences were observed in age, type of community (rural versus urban), prior coronary artery bypass grafting (CABG), and household income. After adjusting for baseline differences, there was a significant association between polygamy and CAD (adjusted OR 4.6 [95% CI 2.5, 8.3]), multivessel disease (MVD) (adjusted OR 2.6 [95% CI 1.8, 3.7]), and left main disease (LMD) (adjusted OR 3.5 [95% CI 2.1, 5.9]). Findings were consistent when the number of wives was analyzed as a continuous variable. In conclusion, among married men undergoing coronary angiography for clinical indications, polygamy is associated with the presence of significant CAD, MVD, and LMD.

Longitudinal synergies between cortisol reactivity and diurnal testosterone and antisocial behavior in young adolescents

The aims were to identify the correspondence between simultaneous, longitudinal changes in cortisol reactivity and diurnal testosterone and to test the hypothesis that cortisol reactivity and diurnal testosterone interact so as to influence antisocial behavior. Participants were 135 children and young adolescents assessed at 6-month intervals over 1 year. Upon enrollment girls were age 8, 10, or 12 years (N = 69, M = 10.06 years) and boys were age 9, 11, or 13 years (N = 66, M = 10.94 years). Assessments included Tanner staging by a nurse, cortisol reactivity (Trier Social Stress Test for Children), diurnal testosterone, and interviews and questionnaires. Growth models showed that cortisol reactivity and diurnal testosterone basal levels (intercept) and rate of change (slopes) were not related, suggesting different mechanisms of growth. Longitudinal regression analyses assessed cortisol reactivity and diurnal testosterone longitudinally. The interactions of cortisol reactivity and diurnal testosterone showed that when diurnal testosterone was low, boys with low cortisol reactivity were reported to have more behavior problems (i.e., oppositional defiant disorder symptoms and attention problems) than when testosterone was high. In addition, when diurnal testosterone was high, boys with high or moderate cortisol reactivity were significantly higher on total antisocial behavior, attention behavior problems, and oppositional defiant disorder symptoms than when testosterone was low or moderate. The results were similar but less frequent for girls. These findings advance the science of young adolescence by showing the interaction between preexisting sensitivity to stressors and the normative testosterone changes of puberty and antisocial behavior.

Somatic and Neuroendocrine Changes in Response to Chronic Corticosterone Exposure During Adolescence in Male and Female Rats

Prolonged stress and repeated activation of the hypothalamic-pituitary-adrenal axis can result in many sex-dependent behavioural and metabolic changes in rats, including alterations in feeding behaviour and reduced body weight. In adults, these effects of stress can be mimicked by corticosterone, a major output of the hypothalamic-pituitary-adrenal axis, and recapitulate the stress-induced sex difference, such that corticosterone-treated males show greater weight loss than females. Similar to adults, chronic stress during adolescence leads to reduced weight gain, particularly in males. However, it is currently unknown whether corticosterone mediates this somatic change and whether additional measures of neuroendocrine function are affected by chronic corticosterone exposure during adolescence in a sex-dependent manner. Therefore, we examined the effects of non-invasively administered corticosterone (150 or 300 μg/ml) in the drinking water of male and female rats throughout adolescent development (30-58 days of age). We found that adolescent animals exposed to chronic corticosterone gain significantly less weight than controls, which may be partly mediated by the effects of corticosterone on food consumption, fluid intake and gonadal hormone function. Our data further show that, despite similar circulating corticosterone levels, males demonstrate a greater sensitivity to these changes than females. We also found that Npy1 and Npy5 receptor mRNA expression, genes implicated in appetite regulation, was significantly reduced in the ventral medial hypothalamus of corticosterone-treated males and females compared to controls. Finally, parameters of gonadal function, such as plasma sex steroid concentrations and weight of reproductive tissues, were reduced by adolescent corticosterone treatment, although only in males. The data obtained in the present study indicate that chronic corticosterone exposure throughout adolescent development results in significant and sex-dependent somatic and neuroendocrine changes, and the results also provide an experimental framework for further investigating the impact of corticosterone on metabolic and neuroendocrine function during adolescence.

Neuroendocrinology of a Male-Specific Pattern for Depression Linked to Alcohol Use Disorder and Suicidal Behavior

Epidemiological studies show low rates of diagnosed depression in men compared to women. At the same time, high rates of alcohol use disorders (AUDs) and completed suicide are found among men. These data suggest that a male-specific pattern for depression may exist that is linked to AUDs and suicidal behavior. To date, no underlying neuroendocrine model for this specific pattern of male depression has been suggested. In this paper, we integrate findings related to this specific pattern of depression with underlying steroid secretion patterns, polymorphisms, and methylation profiles of key genes in order to detail an original neuroendocrine model of male-specific depression. Low circulating levels of sex steroids seem to increase the vulnerability for male depression, while concomitant high levels of glucocorticoids further intensify this vulnerability. Interactions of hypothalamus-pituitary-gonadal (HPG) and hypothalamus-pituitary-adrenocortical (HPA) axis-related hormones seem to be highly relevant for a male-specific pattern of depression linked to AUDs and suicidal behavior. Moreover, genetic variants and the epigenetic profiles of the androgen receptor gene, well-known depression related genes, and HPA axis-related genes were shown to further interact with men's steroid secretion and thus may further contribute to the proposed male-specific pattern for depression. This mini-review points out the multilevel interactions between the HPG and HPA axis for a male-specific pattern of depression linked to AUDs and suicidal behavior. An integration of multilevel interactions within the three-hit concept of vulnerability and resilience concludes the review.

Corticosterone mediates the synaptic and behavioral effects of chronic stress at rat hippocampal temporoammonic synapses

Chronic stress is thought to impart risk for depression via alterations in brain structure and function, but contributions of specific mediators in generating these changes remain unclear. We test the hypothesis that stress-induced increases in corticosterone (CORT), the primary rodent glucocorticoid, are the key mediator of stress-induced depressive-like behavioral changes and synaptic dysfunction in the rat hippocampus. In rats, we correlated changes in cognitive and affective behavioral tasks (spatial memory consolidation, anhedonia, and neohypophagia) with impaired excitatory strength at temporoammonic-CA1 (TA-CA1) synapses, an archetypical stress-sensitive excitatory synapse. We tested whether elevated CORT was sufficient and necessary to generate a depressive-like behavioral phenotype and decreased excitatory signaling observed at TA-CA1 after chronic unpredictable stress (CUS). Chronic CORT administration induced an anhedonia-like behavioral state and neohypophagic behavior. Like CUS, chronic, but not acute, CORT generated an impaired synaptic phenotype characterized by reduced α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-preferring glutamate receptor-mediated excitation at TA-CA1 synapses, decreased AMPA-type glutamate receptor subunit 1 protein expression, and altered serotonin-1B receptor-mediated potentiation. Repeatedly blunting stress-induced increases of CORT during CUS with the CORT synthesis inhibitor metyrapone (MET) prevented these stress-induced neurobehavioral changes. MET also prevented the CUS-induced impairment of spatial memory consolidation. We conclude that corticosterone is sufficient and necessary to mediate glutamatergic dysfunction underlying stress-induced synaptic and behavioral phenotypes. Our results indicate that chronic excessive glucocorticoids cause specific synaptic deficits in the hippocampus, a major center for cognitive and emotional processing, that accompany stress-induced behavioral dysfunction. Maintaining excitatory strength at stress-sensitive synapses at key loci throughout corticomesolimbic reward circuitry appears critical for maintaining normal cognitive and emotional behavior.

Interpreting Stress Responses during Routine Toxicity Studies

Stress often occurs during toxicity studies. The perception of sensory stimuli as stressful primarily results in catecholamine release and activation of the hypothalamic–pituitary–adrenal (HPA) axis to increase serum glucocorticoid concentrations. Downstream effects of these neuroendocrine signals may include decreased total body weights or body weight gain; food consumption and activity; altered organ weights (e.g., thymus, spleen, adrenal); lymphocyte depletion in thymus and spleen; altered circulating leukocyte counts (e.g., increased neutrophils with decreased lymphocytes and eosinophils); and altered reproductive functions. Typically, only some of these findings occur in a given study. Stress responses should be interpreted as secondary (indirect) rather than primary (direct) test article–related findings. Determining whether effects are the result of stress requires a weight-of-evidence approach. The evaluation and interpretation of routinely collected data (standard in-life, clinical pathology, and anatomic pathology endpoints) are appropriate and generally sufficient to assess whether or not changes are secondary to stress. The impact of possible stress-induced effects on data interpretation can partially be mitigated by toxicity study designs that use appropriate control groups (e.g., cohorts treated with vehicle and subjected to the same procedures as those dosed with test article), housing that minimizes isolation and offers environmental enrichment, and experimental procedures that minimize stress and sampling and analytical bias.

This article is a comprehensive overview of the biological aspects of the stress response, beginning with a Summary (Section 1) and an Introduction (Section 2) that describes the historical and conventional methods used to characterize acute and chronic stress responses. These sections are followed by reviews of the primary systems and parameters that regulate and/or are influenced by stress, with an emphasis on parameters evaluated in toxicity studies: In-life Procedures (Section 3), Nervous System (Section 4), Endocrine System (Section 5), Reproductive System (Section 6), Clinical Pathology (Section 7), and Immune System (Section 8). The paper concludes (Section 9) with a brief discussion on Minimizing Stress-Related Effects (9.1.), and a final section explaining why Parameters routinely measured are appropriate for assessing the role of stress in toxicology studies (9.2.).

Deficits in male sexual behavior in adulthood after social instability stress in adolescence in rats

There is increasing evidence that exposure to stressors in adolescence has long-lasting effects on emotional and cognitive behavior, but little is known as to whether reproductive functions are affected. We investigated appetitive and consummatory aspects of sexual behavior in male rats that were exposed to chronic social instability stress (SS, n=24) for 16 days in mid-adolescence compared to control rats (CTL, n=24). Over five sexual behavior test sessions with a receptive female, SS rats made fewer ejaculations (p=0.02) and had longer latencies to ejaculation (p=0.03). When only data from rats that ejaculated in the fifth session were analyzed, SS rats (n=18) had reduced copulatory efficiency (more mounts and intromissions before ejaculation) compared to CTL rats (n=19) (p=0.004), and CTL rats were twice as likely as SS rats to make more than one ejaculation in the fifth session (p=0.05). Further, more CTL (14/24) than SS (5/25) rats ejaculated in four or more sessions (p=0.05). SS rats had lower plasma testosterone concentrations than CTL rats (p=0.05), but did not differ in androgen receptor, estrogen receptor alpha, or Fos immunoreactive cell counts in the medial preoptic area. The groups did not differ in a partner preference test administered between the fourth and fifth sexual behavior session. The results suggest that developmental history contributes to individual differences in reproductive behavior, and that stress exposures in adolescence may be a factor in sexual sluggishness.

Association of methamidophos and sleep loss on reproductive toxicity of male mice

This study investigated the effects of organophosphate exposure on the male reproductive system of mice submitted to chronic sleep loss condition. Adult Swiss mice were distributed into 4 groups: control; methamidophos (MTP); sleep restriction (SR); and MTP+SR. The dose of methamidophos was 0.002 mgkg(-1)day(-1) (half of the Acceptable Daily Intake). Sleep restriction condition was 21 h day(-1) during 15 days. In relation to control group, MTP treatment induced a significant reduction of 12% on morphologically normal spermatozoa in both MTP and MTP+SR groups. In addition, the absolute and relative weights of the seminal vesicles were decreased (MTP, -34%; MTP+SR, -45%). Epididymal fat was reduced in SR groups (SR, -64%; MTP+SR, -58%). Plasma testosterone levels were significantly decreased in MTP and SR groups, and progesterone levels were increased 8 times in MTP+SR in comparison with the control group. The corticosterone levels were unaffected by MTP or SR conditions. Thus, low dose MTP exposure resulted in deleterious effects on the male reproductive system. Sleep loss associated with MTP potentiated the effect on steroidogenesis, mainly in terms of progesterone levels.

Sex and age differences in the impact of the forced swimming test on the levels of steroid hormones

Compared with the adult disorder, depression in children exhibits differences in its neurobiology, particularly in the HPA axis regulation. The bases of such differences can be evaluated in animal models of depression. The objective of the present study was to determine age and sex differences of Wistar rats in the forced swimming test (FST). The influence of sex and age on corticosterone, estrogens and testosterone serum levels was also determined. Prepubertal rats showed immobility, swimming and climbing behaviors during the pre-test and test sessions. In addition, in the prepubertal animals, no sex differences were found during the pre-test and test sessions. Age comparisons indicated no differences in the female groups, however adult males exhibited more immobility and less swimming than young males, in both FST sessions. The young and female rats showed less immobility behavior and increased levels of estrogens after the FST. The present results indicate that the FST is an animal model suitable to evaluate depressive-like behaviors in prepubertal subjects and to explore behavioral changes related to neurodevelopment.

Impact of stress on cancer metastasis

The influence of psychosocial factors on the development and progression of cancer has been a longstanding hypothesis since ancient times. In fact, epidemiological and clinical studies over the past 30 years have provided strong evidence for links between chronic stress, depression and social isolation and cancer progression. By contrast, there is only limited evidence for the role of these behavioral factors in cancer initiation. Recent cellular and molecular studies have identified specific signaling pathways that impact cancer growth and metastasis. This article provides an overview of the relationship between psychosocial factors, specifically chronic stress, and cancer progression.

Neuroendocrine influences on cancer biology

Over the past 25 years, epidemiological and clinical studies have linked psychological factors such as stress, chronic depression, and lack of social support to the incidence and progression of cancer. Although the mechanisms underlying these observations are not completely understood, recent molecular and animal studies have begun to identify specific signaling pathways that could explain the impact of neuroendocrine effects on tumor growth and metastasis. This review will highlight the importance of known clinical, molecular, and cellular processes with regard to the neuroendocrine stress effects on tumor biology and discuss possible behavioral and pharmacological interventions to ameliorate these effects and ultimately improve cancer outcomes.

S179D prolactin diminishes the effects of UV light on epidermal gamma delta T cells

Epidermal gamma delta T cells (gammadeltaT) and Langerhans cells (LC) are immune cells altered by exposure to ultraviolet radiation (UVB), a powerful stressor resulting in immune suppression. Prolactin (PRL) has been characterized as an immunomodulator, particularly during stress. In this study, we have asked whether separate administration of the 2 major forms of prolactin, unmodified and phosphorylated, to groups of 15 mice (3 experiments, each with 5 mice per treatment group) affected the number and morphology of these epidermal immune cells under control conditions, and following UV-irradiation. Under control conditions, both PRLs reduced the number of gammadeltaT, but a molecular mimic of phosphorylated PRL (S179D PRL) was more effective, resulting in a 30% reduction. In the irradiated group, however, S179D PRL was protective against a UV-induced reduction in gammadeltaT number and change in morphology (halved the reduction and normalized the morphology). In addition, S179D PRL, but not unmodified (U-PRL), maintained a normal LC:gammadeltaT ratio and sustained the dendritic morphology of LC after UV exposure. These findings suggest that S179D PRL may have an overall protective effect, countering UV-induced cellular alterations in the epidermis.

The influence of bio-behavioural factors on tumour biology: pathways and mechanisms

Epidemiological studies indicate that stress, chronic depression and lack of social support might serve as risk factors for cancer development and progression. Recent cellular and molecular studies have identified biological processes that could potentially mediate such effects. This review integrates clinical, cellular and molecular studies to provide a mechanistic understanding of the interface between biological and behavioural influences in cancer, and identifies novel behavioural or pharmacological interventions that might help improve cancer outcomes.

Prolonged deleterious effects of neonatal handling on reproductive parameters of pubertal male rats

The purpose of the present study was to investigate the long-lasting effects of neonatal handling on reproductive parameters of male rats. Neonatal handling (pups separated from their mothers, kept isolated at environmental temperature for 20 min and submitted to 1 min of tactile stimulation) was applied from post partum Days 1 to 14 (a stress-hyporesponsive period, SHRP) and the animals were killed at puberty (61 days of age). The number of mature spermatids and the daily sperm production were estimated in homogenates from the right testes and cauda epididymidis. Histometric parameters (diameter of seminiferous tubule, germinal epithelium thickness and number of Sertoli cells) were evaluated in paraplast sections of the left testes. The association of the slightly aversive stimuli applied during the SHRP proved to have lasting deleterious effects on male reproduction, causing lower testicular weight and reduced values of seminiferous tubule diameter and germinal epithelium thickness at puberty, which resulted in a 25% reduction in the daily sperm production and in the number of mature spermatids. Similarly, the number of Sertoli cells per tubular cross section was 20% smaller and the weight and number of spermatozoa were reduced more than 40% in the cauda epididymidis of animals handled.

Sleep pattern in rats under different stress modalities

The present study was designed to evaluate the sleep pattern of rats submitted to chronic stressors (restraint, electrical footshock, swimming and cold) applied to male rats. After 48 h-baseline recording, rats were submitted to 4 days of chronic stress, and electrocorticogram recordings were carried out continuously. The stressors (footshock, swimming and cold) were applied twice a day for periods of 1 h at 9:00 and 16:00 h. Restrained animals were maintained in plastic cylinders for 22 h/day. The findings indicated that sleep efficiency, slow wave sleep (SWS) and paradoxical sleep (PS) were decreased on the third and fourth days of unpredictable shocks compared to baseline while immobilization and swimming presented reduced sleep efficiency in all 4-day recordings. Swimming led to decreased SWS, whereas augmented PS was observed on the first day compared to baseline. Immobilization produced drastic alterations in sleep patterns since it reduced SWS during the 4 days and PS at days 1 to 4 in relation to baseline. Of all stressors, cold was the only one that did not result in any statistical differences in sleep pattern during the light periods. Regarding the effect of stress compared to baseline on the dark recordings, PS was higher during cold stress periods, whereas footshock increased PS on days 2 to 4 and swimming only on day 2. Immobilization decreased PS throughout the 4 days of the stress sessions. Thus, the data suggest that different stress modalities result in distinct sleep responses, with immobilization producing the most dramatic alterations.

Abrogation of delayed type hypersensitivity response to Candida albicans produced by a molecular mimic of phosphorylated prolactin

The effects of two major forms of prolactin (PRL) were examined on delayed type hypersensitivity (DTH) responses to Candida albicans. Unmodified PRL (U-PRL) had no effect on the DTH response, whereas a molecular mimic of phosphorylated PRL (S179D PRL) significantly inhibited immune responses to this robust antigen. This effect of S179D PRL was not accompanied by gross alterations in splenic T cell numbers, CD4/CD8 ratios, or T and B cell activation markers, but did produce a decrease in splenocyte apoptosis. Using gld animals, Fas ligand (FasL) was implicated in the suppressive effects of S179D PRL. Circulating IgG1 and IgG2 antibody levels were increased in response to treatment with both forms of PRL, but the effects of S179D PRL were most pronounced. Cytokine changes in the popliteal lymph nodes specific to S179D PRL treatment showed an inhibition of pro-inflammatory cytokines. In conclusion, mice treated with a molecular mimic of phosphorylated prolactin showed a profound inhibition of DTH responses to Candida correlating with an absence of GM-CSF, IL-4, and IL-13 production and a marked reduction in IL-12p70 synthesis.

Cloacal Gland and Testes Development in Male Japanese Quail Selected for Divergent Adrenocortical Responsiveness

The time course of sexual development in male quail from lines selected for either a reduced (low stress, LS) or an exaggerated (high stress, HS) plasma corticosterone response to brief restraint was determined. Sexual development was assessed by examination of cloacal gland area (CAREA) and volume (CVOL), proportion of individuals that produced cloacal gland foam, and the intensity of cloacal gland foam production (CFP) at 4, 5, 6, 8, 10, 14, and 16 wk of age. These intervals encompass ages during which growing, photostimulated quail would be expected to evolve from being totally prepubescent to well into adulthood. Testes weight (TW) and the proportion of individuals that had achieved a combined TW of 500 mg (PI500) were also measured at 6 and 16 wk of age. Mean CAREA and CVOL were similar in LS and HS quail at 4 wk of age. Beginning at 5 wk of age and thereafter, CAREA was greater (P < 0.05) in LS than in HS quail. Similarly, beginning at 6 wk of age and thereafter, CVOL was greater (P < 0.05) in LS than in HS quail. More LS than HS birds also expressed foam at 4 (P < 0.05), 5 (P = 0.15), and 6 wk (P < 0.05) of age. From 8 wk on, all birds were in foam production. CFP results mimicked those found for CAREA and CVOL in that LS quail tended toward higher CFP values than HS quail at all intervals of measurement. TW were higher (P < 0.02) in LS than HS quail when data from the 2 ages at which testes were harvested were combined. At 6 wk of age, the LS and HS birds showed a PI500 line difference (P < 0.08) of 1.0 and 0.91, respectively; by 16 wk, all birds exhibited a maximum PI500. The results suggest that 1) selection for reduced adrenocortical responsiveness in Coturnix is accompanied by an accelerated onset of puberty in males, and 2) enhanced reproductive development in LS males remains extant throughout early to middle-age adulthood.

Different stress modalities result in distinct steroid hormone responses by male rats

Since both paradoxical sleep deprivation (PSD) and stress alter male reproductive function, the purpose of the present study was to examine the influence of PSD and other stressors (restraint, electrical footshock, cold and forced swimming, N = 10 per group) on steroid hormones in adult Wistar male rats. Rats were submitted to chronic stress for four days. The stressors (footshock, cold and forced swimming) were applied twice a day, for periods of 1 h at 9:00 and 16:00 h. Restrained animals were maintained in plastic cylinders for 22 h/day whereas PSD was continuous. Hormone determination was measured by chemiluminescent enzyme immunoassay (testosterone), competitive immunoassay (progesterone) and by radioimmunoassay (corticosterone, estradiol, estrone). The findings indicate that PSD (13.7 ng/dl), footshock (31.7 ng/dl) and cold (35.2 ng/dl) led to lower testosterone levels compared to the swimming (370.4 ng/dl) and control (371.4 ng/dl) groups. However, progesterone levels were elevated in the footshock (4.5 ng/ml) and PSD (5.4 ng/ml) groups compared to control (1.6 ng/ml), swimming (1.1 ng/ml), cold (2.3 ng/ml), and restrained (1.2 ng/ml) animals. Estrone and estradiol levels were reduced in the PSD, footshock and restraint groups compared to the control, swimming and cold groups. A significant increase in corticosterone levels was found only in the PSD (299.8 ng/ml) and footshock (169.6 ng/ml) groups. These changes may be thought to be the full steroidal response to stress of significant intensity. Thus, the data suggest that different stress modalities result in distinct steroid hormone responses, with PSD and footshock being the most similar.

Changes in masculine sexual behavior, corticosterone and testosterone in response to acute and chronic stress in male rats

Chronic exposure to stressors increases HPA axis activity and concomitantly reduces HPG axis activity. This antagonistic relationship between both these axes has been proposed to underlie the inhibition of reproductive function due to stress. Sexual behavior in males may be the most vulnerable aspect of male reproduction to acute and chronic stress and it has been suggested that alterations in sexual behavior during stress are due to the antagonistic relationship between testosterone and corticosteroids. However, only in a few studies has a correlation between the levels of testosterone and corticosterone, and sexual behavior been made. In this study, we evaluated the effects of different stressors, applied both acute and chronically, on masculine sexual behavior and whether or not these effects on sexual behavior are accompanied by changes in plasma levels of corticosterone and testosterone. Additionally, we evaluated the effect of testosterone treatment on the effects of stress on sexual behavior. Sexually experienced male rats were exposed to one of the following stressors: immobilization (IMB), electric foot shocks (EFS) or immersion in cold water (ICW). Sexual behavior and plasma levels of testosterone and corticosterone were assessed on days 1, 5, 10, 15, and 20 of stress. In a second experiment, males were castrated, treated with 3 different doses of testosterone propionate (TP) and exposed to ICW for 20 consecutive days. Sexual behavior was assessed on days 1, 5, 10, 15, and 20 and steroids were evaluated on day 20. Parameters of masculine sexual behavior were modified depending on the characteristics of each stressor. Mount, intromission and ejaculation latencies increased significantly, the number of mounts increased, and ejaculations decreased significantly in males exposed to EFS and to ICW but not in males exposed to IMB. Associated with these effects, testosterone decreased in the EFS and ICW groups on days 1, 15, and 20. However, corticosterone increased only in males exposed to ICW. In castrated males, TP treatment failed to block the effects of stress by ICW on sexual behavior and corticosterone. These results indicate that the effects of stress on sexual behavior depend on the characteristics of each stressor, and these effects, as well as the decrease in testosterone are not necessarily associated with the increase in corticosterone. The fact that testosterone treatment did not prevent the effects of stress on sexual behavior suggests that other mediators could be involved in the alterations of sexual behavior caused by stress.

Effect of intensive exercise-induced testicular gametogenic and steroidogenic disorders in mature male Wistar strain rats: a correlative approach to oxidative stress

AIMS

In order to investigate the effects of intensive exercise on reproductive dysfunctions in relation to oxidative stress, a total of 12 male rats (age: 3 months, weight: 127 +/- 2.86 g) were randomly divided into: (1) control group (CG, n = 6) and (2) experimental group (Exp. G, n = 6).

METHODS

An exercise protocol of 3 h swimming day(-1), 5 days week(-1) was followed for 4 weeks in Exp. G, with no exercise in CG. All the animals were killed; blood, testes and the accessory sex organs were collected for estimation of different parameters.

RESULTS

A significant diminution (P < 0.001) was noted in testicular Delta5, 3beta-hydroxy-steroid dehydrogenase (Delta5, 3beta-HSD), 17beta-hydroxy steroid dehydrogenase (17beta-HSD); plasma levels of testosterone, luteinizing hormone (LH); preleptotine spermatocytes (pLSc), midpachytene spermatocytes (mPSc) and stage 7 spermatids (7Sd); with no significant alteration in follicle stimulating hormone (FSH) and spermatogoia A (Asg) after intensive exercise. A significant elevation (P < 0.001) in malondialdehyde (MDA) and conjugated dienes (CD) along with significant reduction (P < 0.001) in glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), glutathione-s-transferase (GST) and peroxidase were found in testes of Exp. G. Moreover, the somatic index of testes and accessory sex organs were also decreased significantly (P < 0.001) after exercise. High correlations have been found in 17 beta-HSD with CAT (r = 0.90, P < 0.05) and peroxidase (r = 0.83, P < 0.05), epididymal somatic index with CD (r = -0.91; P < 0.05) and GSH (r = 0.84, P < 0.05).

CONCLUSION

The present study focused an chronic intensive exercise-induced oxidative stress that may cause dysfunctions in male reproductive system including steroidogenesis and spermatogenesis.

Influence of paradoxical sleep deprivation and cocaine on development of spontaneous penile reflexes in rats of different ages

Recent studies have established that paradoxical sleep deprivation (PSD) and cocaine administration induce genital reflexes (penile erection and ejaculation) in adult and old rats. To determine whether the same effects would induce spontaneous genital reflexes in rats of different ages (30-90 days old), we administered with cocaine (7 mg/kg) or saline to rats after a 4-day period of PSD, or at the equivalent time-point in control animals, and penile erection and ejaculation were then evaluated. In PSD rats administered cocaine, erection was observed from 30 days old to 90 days old, when both genital reflexes reached a peak. Animals submitted to PSD and saline injection showed erection from 60 to 90 days old. None of the control (saline and cocaine) groups of any age displayed these behaviors. The effects of PSD on steroid hormone levels showed that, although testosterone levels increased with age, PSD caused a marked decrease in testosterone at all ages evaluated. Progesterone and corticosterone levels were higher in PSD groups than in the respective control groups. These findings suggest that the interaction of PSD and cocaine probably enhances dopaminergic transmission in the brain and may accelerate the development of genital reflexes in male rats.

Selection of Japanese quail for reduced adrenocortical responsiveness accelerates puberty in males

Differences in the onset of puberty were assessed in male Japanese quail from a random-bred (RB, control) line and two lines that had been genetically selected for reduced (low stress, LS) or exaggerated (high stress, HS) plasma corticosterone response to brief mechanical restraint. At 42 d of age, cloacal gland area (CAREA) and volume (CVOL), proportion of individuals that produced cloacal gland foam (PICF), and intensity of cloacal gland foam production (CFP) were examined in 60 representatives from each of these quail lines. CFP was quantified by subjective scaling of the amount of foam ejected upon manual expression (squeezing) of the foam gland, using a scale of 1 (no foam expressed) to 5 (maximum amount of foam expression). Mean CAREA and CVOL were similar in quail of the RB and HS lines, but these measures were greater (P < 0.01) in the LS quail. In addition, more (P < 0.05) LS than HS birds expressed foam at 42 d, whereas RB quail exhibited an intermediate PICF response that was not different from either selected line. CFP results mimicked those found for PICF (i.e., LS quail produced a greater (P < 0.05) amount of foam than HS birds, whereas RB quail showed intermediate production that was not different from LS or HS levels). In prepubertal and pubertal Japanese quail, cloacal gland hypertrophy is androgen-dependent and highly positively correlated with testes size as well as sexual activity. Cloacal gland foam production is also considered a reliable indicator of testicular size and activity. Thus, we conclude that selection for reduced adrenocortical responsiveness in Coturnix is associated with acceleration in the onset of puberty in males. The potential interaction between adrenocortical and testicular activity as it relates to male reproductive performance is discussed.

Stress inhibits seasonal and FSH-induced ovarian recrudescence in the lizard,Mabuya carinata

Stressors (handling, chasing, and noise) applied randomly five times per day for one month to lizards during the recrudescence phase of the ovarian cycle caused a significant reduction in mean number of oocytes and primordial follicles when compared to those of controls. Further, vitellogenic follicles were absent in the ovary of lizards subjected to stressors. Administration of bovine FSH during post-breeding regression phase of the ovarian cycle induced ovarian recrudescence as shown by significant increases in the mean number of oogonia, oocytes, and primordial follicles compared to controls, as well as vitellogenic growth of follicles. However, lizards treated with FSH and exposed to stressors did not exhibit ovarian recrudescence. Furthermore, FSH administration during the post-breeding regression phase caused a significant increase in serum levels of estradiol compared to controls, which was accompanied by significant increases in the relative weight of the liver and oviduct, as well as vitellogenic growth of follicles. Despite administration of FSH to lizards subjected to stressors, there was neither any increase in serum levels of estradiol and weight of the liver nor vitellogenic growth of follicles. The results indicate that repeated application of stressors inhibits vitellogenic growth of follicles by suppression of steroidogenic activity in M. carinata. This is the first report revealing that the ovary does not respond to gonadotrophin treatment under stressful conditions in reptiles.

Long-term (6-wk) hindlimb suspension inhibits spermatogenesis in adult male rats

The International Space Station will allow extended habitation in space and long-term exposure to microgravity (microG). A concern is the impact of long-term microG exposure on the ability of species to reproduce. The model often used to simulate microG is rat hindlimb suspension (HLS), where the hindlimbs are elevated above the cage floor with a tail harness. Experiments described here are the first to examine the effect of long-term HLS on testicular function in adult male rats. Free-roaming (controls), animals with only the tail harnessed but hindlimbs in contact with the cage floor (TO), and HLS animals were tested for 6 wk. Cryptorchidism was prevented in TO and HLS animals by partial constriction of the inguinal canal with sutures. All parameters were compared at the end of the 6-wk experiment. Testicular weights and spermatogenesis were significantly reduced by HLS, such that no spermatogenic cells beyond round spermatids were present and epididymides were devoid of mature sperm. In many tubules, loss of all germ cells, except a few spermatogonia, resulting in histopathology similar to the Sertoli cell, was observed. Spermatogenesis appeared unaffected in control and TO animals. Sertoli and Leydig cell appearance, testosterone, luteinizing hormone, and follicle-stimulating hormone levels, and epididymal and seminal vesicle weight were unchanged by HLS. Cortisone was not elevated by HLS; thus stress may not be a factor. These results demonstrate that spermatogenesis is severely inhibited by long-term HLS, whereas testicular androgen production is not. These results have significant implications regarding serious effects of long-term exposure to microG on the reproductive capability of scrotal mammals, including humans.

Sexual behavior and fertility of male rats submitted to prolonged immobilization-induced stress

In order to investigate whether prolonged stress interferes with the onset of sexual behavior at puberty and with fertility at adulthood, prepubertal male Wistar rats (40 days of age) were immobilized 6 h a day for 15 days (up to early puberty) or for 60 days (until sexual maturity). Pubertal stressed rats showed a two-fold increase in the latency for the first mount (probably due to repeated aversive experience in which a change of environment was always followed by immobilization) and a 2.5-fold increase in the frequency of thrusting (indicative of enhanced sexual performance). The apparently stimulatory effect of prolonged stress on the onset of sexual behavior is discussed in terms of increased testosterone level and interference with the complex interchanges between the neurotransmitters/neuropeptides involved in the central control of male sexual activity. Adult stressed animals were mated with normal females, which became pregnant but exhibited a more than two-fold increase in both pre-implantation and post-implantation loss, probably due to a smaller rate of fertilization and/or fertilization with damaged spermatozoa.