SEX DIFFERENCES IN SKIN CONDUCTANCE MEASURES AS A FUNCTION OF SHOCK THREAT

Investigations of sex differences in various electrodermal measures have yielded inconsistent results. The present investigation attempted to examine sex differences primarily as a function of varied conditions of threat (stated probability of receiving electric shock). Thirty males and 30 females were randomly assigned to three conditions: High Threat Probability (HTP), Moderate Threat Probability (MTP), or No Threat Probability (NTP). All Ss heard, under assigned threat instructions, 2 sets of 11 tones, preceded by a nonstimulation period and followed by 11 tones with shock threat removed. Results indicated that the threat conditions did affect electrodermal measures as expected. In addition, males exhibited higher tonic (basal conductance) levels throughout, while females displayed greater phasic reactivity (GSR magnitude) and a larger number of nonspecific GSRs. In addition, nonspecific frequency was affected by the interaction of sex with treatment (threat), such that females displayed higher frequencies under moderate threat, while males increased linearly with increased threat. Degree of stress or threat, the possibility of differential perceptions, and a theory of differential hormonal functioning were applied in interpreting results.     

Functional organization of the insula in men and women with obstructive sleep apnea during Valsalva

Study ObjectivesObstructive sleep apnea (OSA) patients show impaired autonomic regulation, perhaps related to functional reorganization of the insula, which in healthy individuals shows sex-specific anterior and right dominance during sympathetic activation. We examined insular organization of responses to a Valsalva maneuver in OSA with functional magnetic resonance imaging (fMRI).MethodsWe studied 43 newly diagnosed OSA (age mean ± SD: 46.8 ± 8.7 years; apnea-hypopnea index (AHI) ± SD: 32.1 ± 20.1 events/hour; 34 males) and 63 healthy (47.2 ± 8.8 years; 40 males) participants. Participants performed four 18-second Valsalva maneuvers (1-minute intervals, pressure ≥ 30 mmHg) during scanning. fMRI time trends from five insular gyri—anterior short (ASG); mid short (MSG); posterior short (PSG); anterior long (ALG); and posterior long (PLG)—were assessed for within-group responses and between-group differences with repeated measures ANOVA (p < 0.05); age and resting heart rate (HR) influences were also assessed.ResultsRight and anterior fMRI signal dominance appeared in OSA and controls, with no between-group differences. Separation by sex revealed group differences. Left ASG anterior signal dominance was lower in OSA versus control males. Left ASG and ALG anterior dominance was higher in OSA versus control females. In all right gyri, only OSA females showed greater anterior dominance than controls. Right dominance was apparent in PSG and ALG in all groups; females showed right dominance in MSG and PLG. OSA males did not show PLG right dominance. Responses were influenced substantially by HR but modestly by age.ConclusionsAnterior and right insular fMRI dominance appears similar in OSA versus control participants during the sympathetic phase of the Valsalva maneuver. OSA and control similarities were present in just males, but not necessarily females, which may reflect sex-specific neural injury.     

Sex differences and the asymmetry of specific and non-specific electrodermal responses

Phasic electrodermal conductance responses were bilaterally recorded from 30 subjects (15 males and 15 females). After a 5-min adaptation period subjects were presented with two series of ten 80-dB tones each, with a 4-min rest period between the two series. Data from sinistrals, ambidextrous, and from subjects with familial sinistrality were excluded from statistical analysis. Males displayed more asymmetry between hands both in their non-specific and specific responses, with larger skin conductance responses on the left hand. Females showed a less marked asymmetry, with larger skin conductance responses on the right hand. Similar results were found in skin conductance levels. It was concluded that sex differences are an important variable in the study of electrodermal asymmetry.     

Sex-differences in age-related cognitive decline in C57BL/6J mice associated with increased brain microtubule-associated protein 2 and synaptophysin immunoreactivity

Understanding cognitive aging is becoming more important as the elderly population grows. Here, the effects of age and sex on learning and memory performance were compared in female and male young (3-4 months old) middle-aged (10-12 months old) and old (18-20 months old) wild-type C57BL/6J mice. Old males and females performed worse than young or middle-aged mice in novel location, but not novel object recognition tasks. Old mice, of both sexes, also showed impaired spatial water maze performance during training compared with young or middle-aged mice, however only old females failed to show robust spatial bias during probe trials. While there was no age-difference in passive avoidance performance for males, females showed an age-related decline. There was no difference in cognitive performance between young and middle-age mice of either sex on any task. Cognitive performance was associated with alterations in immunoreactivity of microtubule-associated protein 2-positive dendrites and synaptophysin-positive pre-synaptic terminals in hippocampal CA1, CA3, and dentate, entorhinal cortex, and central nucleus of amygdala. Overall, microtubule-associated protein 2 immunoreactivity was increased in old females compared with both young and middle-age females with no significant difference in males. In contrast, synaptophysin immunoreactivity increased from young to middle-age in females, and from middle-age to old in males; females had higher levels of synaptophysin immunoreactivity than males in middle-age only. Elevated levels of microtubule-associated protein 2 and synaptophysin may constitute a compensatory response to age-related functional decline in mice.     

Sexual behaviors of aging female rats: influence of age and hormonal state of male partners

Proceptive and receptive behaviors were examined in aging and young ovariectomized female rats treated with estradiol benzoate and progesterone. Young females approached males confined in wire mesh cages more frequently and exhibited more proceptive behaviors toward these males than did middle-aged females. Both middle-aged and young females approached young males more often than they approached old males, but young females showed greater preferences for young males and for males with high levels of testosterone than did middle-aged females. Young females also exhibited more proceptive behaviors than did middle-aged and old females during tests of sexual behavior. The frequencies of lordosis responses, however, did not differ among these three groups of females.     

Comparisons of Sweat Gland Counts, Electrodermal Activity, and Habituation Behavior in Young and Old Groups of Subjects

The present experiment utilized a habituation paradigm to investigate age differences in sweat gland counts (SGC), skin conductance responses (SCR), and skin conductance levels (SCL). The 12 young subjects (mean age 25.3 yrs) and the 12 old subjects (mean age 69.5 yrs) exhibited no reliable age differences in habituation of the SCR or in the magnitude of the SCRs measured. Bilateral conductance recordings revealed no laterality effects for SCR or SCL in either age group. Age differences were found for both SGC and SCL. Correlations of SGC with SCL revealed a strong relationship in the young (r= 74) and a relatively weak correspondence in the elderly (r= .22). The reverse was observed for SGC and SCR correlations, with the old sample showing consistently high correlations and the younger sample consistently low correlations. A stepwise multiple regression analysis showed that the variance in SCL predicted by age was not independent of the variance predicted by differences in SGC. The data are discussed in terms of age-related change in peripheral factors which affect electrodermal behavior.     

The cardiovascular response to arousal from sleep decreases with age in healthy adults

STUDY OBJECTIVES: To investigate age and gender effects on the acute blood pressure (BP) and heart rate (HR) response to arousal from sleep in healthy adults. DESIGN: Healthy young and older male and female adults were aroused from stage 2 sleep throughout the night using an auditory tone. The magnitude of the cardiovascular responses to arousal were assessed using 2 (young v older) by 2 (male v female) ANOVAs with repeated measures over time. SETTING: Sleep laboratory at the Royal Brompton Hospital, London. PATIENTS OR PARTICIPANTS: 25 healthy young (< or = 40 years, n = 15 males) and 20 healthy older adults (> or = 60 years, n = 11 males). INTERVENTIONS: Arousals (> 10 seconds) from undisturbed stage 2 sleep were induced by an auditory tone throughout the night. MEASUREMENTS AND RESULTS: Overnight polysomnography (PSG) with HR, continuous beat-by-beat arterial BP and respiratory measurements was performed. Older adults had smaller and delayed initial mean BP and HR responses to arousal compared to young adults (both P < 0.001), whereas changes in ventilation and tidal volume responses to arousal were similar between age groups (P = 0.3 and P = 0.6 respectively).There were no differences between females and males in the cardiovascular or respiratory responses to arousal from sleep. CONCLUSION: The cause of the smaller and delayed response in healthy older adults is unknown; however, we speculate that for older people with sleep apnea, in whom nocturnal arousals occur frequently, the reduced cardiovascular response may be protective against the link between sleep apnea and hypertension.     

不同年龄及性别健康成人血浆同型半胱氨酸的水平研究

目的: 分析不同性别及年龄健康成人的血浆同型半胱氨酸(Hcy)水平,明确健康人群Hcy的标准,为高Hcy血症的防治提供指导和依据。方法: 剔除高血压、脑卒中、冠心病等常见致血Hcy升高因素的健康体检人群,共738人,按不同年龄分为青(≤35岁)、中(≥36,<60岁)、老(≥60岁)3组,并按性别分为男女亚组,以循环酶法分别测定其血浆Hcy水平,进行比较。结果: 各年龄组男性均高于女性(P<0.01);同时男女各组Hcy均随年龄增加而升高,青、中、老组比均有显著差异(P<0.01);男性均数为13.26 μmol/L,女性为9.68 μmol/L,差异显著(P<0.01); 多数男性(73.21%)血Hcy水平在10.01-15.00 μmol/L间,多数女性(84.06%)小于10.00 μmol/L。 结论: (1) 健康成人血浆Hcy水平存在性别和年龄的差异,男性高于女性,并随年龄增加而逐渐升高。(2) 正常健康成人血浆Hcy水平高限的确定,应考虑性别及年龄因素。     

The influence of age and pregnancy on immune responses of baboons to mitogens and the baboon endogenous virus

Immune responses to mitogens and baboon endogenous type C virus (BaEV) were assessed in baboons according to age, sex, and at various stages of pregnancy. Generally there were no significant differences noted in the immunologic responses between males and females. However, age and pregnancy had pronounced effects on mitogen responses and specific humoral and cell-mediated immunity (CMI) to BaEV. Lymphocyte responses to mitogens declined with increasing age and were significantly suppressed in the third trimester of pregnancy. Humoral immunity (HI) to BaEV assayed by radioimmunoprecipitation (RIP) was observed in pregnant, but not age-matched nonpregnant, baboons and this reactivity declined with increasing time of pregnancy. In nonpregnant animals, RIP antibodies were only detected in very young (<1 years of age) and old (>-12 years of age) baboons. CMI as assayed by lymphocyte blastogenesis (LB) and macrophage migration inhibitory factor (MIF) was suppressed during pregnancy. In relation to age LB responses to BaEV did not follow a clear pattern; however, MIF (like RIP) was only found in young (<1 years of age) and old (≥12 years of age) baboons. These data indicate a decreased response of baboon lymphocytes to mitogens and increased reactivity to BaEV during pregnancy and old age.     

EFFECTS OF SET AND SEX ON THE ELECTRODERMAL ORIENTING RESPONSE

This study sought to determine the extent to which brief instructions to “pay attention” would affect the magnitude and rate of habituation of the electrodermal orienting response (OR) and whether sex differences would be obtained. Compared to neutral (relaxation) instructions, it was found that Ss who were told to pay attention: (1) had larger ORs to the first tone in each of 2 sets of 20 tones, (2) showed more irregular habituation over the second set of tones, and (3) exhibited decreases in base conductance during a rest period between sets of tones. Females habituated faster than males over the first set of tones. The results are discussed in terms of preparatory set variables.     

Resting intracellular calcium concentration,depolarizing Gamma-Aminobutyric Acid and possible role of local estradiol synthesis in the developing male and female hippocampus

The maturation of the hippocampus is impacted by a multitude of factors, including the regulation of intracellular calcium levels. Depolarizing actions of Gamma-Aminobutyric Acid (GABA) can profoundly alter intracellular calcium in immature hippocampal neurons via influx through voltage-gated calcium channels. We here report fundamental sex differences in properties of depolarizing GABA responses and in resting intracellular calcium in neonatal cultured hippocampal neurons. The effects of the estrogen receptor antagonist, ICI 182,780, and the estradiol-synthesis inhibitor, formestane, indicate the sex differences in depolarizing GABA responses are at least in part due to de novo estradiol synthesis by female neurons, whereas a sex difference in resting calcium is independent of steroids. We postulate that local estradiol synthesis in cultured female hippocampal neurons affects the kinetics of either the GABA_A receptor or voltage sensitive calcium channels. These data highlight the fact that immature hippocampal neurons exhibit fundamentally different physiological properties in males versus females. Elucidating how and where immature male and female neurons differ is essential for a complete understanding of normal rodent brain development.     

Sex differences in latencies of bilateral electrodermal responses

The present study examined sex differences in the latencies of bilateral electrodermal responses to stimuli presented in monocular vision. The stimuli were spatial-emotional, verbal-emotional, spatial-neutral and verbal-neutral slides, presented for either 35 ms or 1 s. Subjects were 15 males and 15 females. Bilateral latencies were not influenced by type of stimulus or by right/left hemisphere stimulation, which is in keeping with the most recent findings of bilateral electrodermal activity studies. However, females gave a faster right hand than left hand response and appeared to be more lateralized than males. Males showed shorter latencies on the left hand than on the right. These results confirm the importance of gender in experiments using the bilateral recordings of electrodermal activity.     

Effects of early weaning on anxiety and prefrontal cortical and hippocampal myelination in male and female Wistar rats

We investigated developmental changes in myelin formation in the prefrontal cortex and the hippocampus, and behavioral effects of early weaning in Wistar rats. Early-weaned rats showed decreased numbers of open-arm entries in an elevated plus-maze in both sexes at 4 weeks old; this effect persisted in males, but ceased in females after this age. Expression of myelin basic protein (MBP) showed both age-dependent increases and sex differences; 4-week-old males exhibited higher MBP levels in the hippocampus, whereas 7-week-old males showed lower MBP levels in the prefrontal cortex compared to females of the same age. There was a tendency for group differences from weaning for the 21.5-kDa isoform in the prefrontal cortex. Although these results suggest that male rats are more vulnerable than females to early-weaning effects on anxiety-related behaviors, further detailed analysis is needed to clarify the functional relationship between myelination and anxiety-related behaviors.     

Age- and sex-specific changes in naloxone-induced luteinizing hormone secretion and Fos expression in gonadotropin-releasing hormone neurons of gonadectomized rats

In the present study, we examined sex-specific changes in luteinizing hormone (LH) secretion and Fos expression in gonadotropin-releasing hormone (GnRH) neurons in response to naloxone in young (3 months old) and old (24 months old), gonadectomized male and female rats. We revealed by immunocytochemistry that, regardless of age and sex, naloxone significantly increased the number of GnRH neurons expressing Fos, which was associated with increased LH secretion. Additionally, although the magnitude of the increase in Fos-expressing GnRH neurons did not change in old males compared to young males, it was attenuated by almost half in old females compared to young females. LH levels decreased 60% in old males compared to young males and 15% in old females compared to young females. These results suggest LH secretion is impaired with age, but the ability of GnRH neurons to be stimulated by naloxone is preserved. However, the opioid-controlling mechanism is more fragile in females than males during aging.     

Time of Quarter Effect: An Uncontrolled Variable in Electrodermal Research

Does the time of the academic quarter in which a subject participates in an electrodermal habituation study have an effect upon electrodermal response components—e.g., skin conductance level (SCL), skin conductance response (SCR), and spontaneous fluctuation (SF) activity? Four groups of 24 undergraduates (12 males and 12 females each) participated in an habituation session consisting of a 10-min adaptation period and 15, 5-sec bursts of 85 dB white noise, during the first, fourth, seventh, or tenth week of an eleven-week quarter. Predictably, all three dependent variables were affected by the time of quarter (TOQ) manipulation and/or by the interaction of this variable with the sex of the participant. Relationships between three meteorological variables—temperature, humidity, and barometric pressure—and the electrodermal variables were also quantified. Several of the correlations between these meteorological variables and the electrodermal measures were found to be significantly greater than zero; however, when employed as covariates, these meteorological variables failed to significantly modify the effects of the independent variable manipulations upon the electrodermal measures. Results are discussed in terms of the need to adequately control for this potentially confounding variable in electrodermal research.     

Conditioning with facial expressions of emotion: Effects of CS sex and age

Two experiments examined the effects of facial expressions of emotion as conditioned stimuli (CSs) on human electrodermal conditioning and on a continuous measure of expectancy of the shock unconditioned stimulus. In Experiment 1, the CS+ was a picture of a person displaying an angry face and CS? was a neutral face. For half of the subjects, the expressions were depicted by males, for the other half by females. Male subjects showed larger skin conductance responses to pictures of males than did females. The responding of female subjects was the same regardless of the sex of the person in the picture. In Experiment 2, the CS+ and CS? were pictures of an angry or a happy face. For half of the subjects, the expressions were depicted by adult males, for the other half by preadolescent males, Subjects displayed greater differentiation when an adult male depicting anger was employed as the CS+ than when a preadolescent male depicting anger was the CS+. There were no differences when an adult or a child displayed happiness.     

Ontogeny of sex differences in response to novel objects from adolescence to adulthood in lister-hooded rats

In humans, novelty-seeking behavior peaks in adolescence and is higher in males than females. Relatively, little information is available regarding age and sex differences in response to novelty in rodents. In this study, male and female Lister-hooded rats were tested at early adolescence (postnatal day, pnd, 28), mid-adolescence (pnd 40), or early adulthood (pnd 80) in a novel object recognition task (n = 12 males/females per age group). Males displayed a higher preference for the novel object than females at mid-adolescence, with no sex difference at early adolescence. Adult females interacted with the novel object more than adult males, but not when side biases were removed. Sex differences at mid-adolescence were not found in other measures, suggesting that the difference at this age was specific to situations involving choice of novelty. The results are considered in the context of age- and sex-dependent interactions between gonadal hormones and the dopamine system.     

A strategic research alliance: Turner syndrome and sex differences

Sex chromosome constitution varies in the human population, both between the sexes (46,XX females and 46,XY males), and within the sexes (e.g., 45,X and 46,XX females, and 47,XXY and 46,XY males). Coincident with this genetic variation are numerous phenotypic differences between males and females, and individuals with sex chromosome aneuploidy. However, the molecular mechanisms by which sex chromosome constitution impacts phenotypes at the cellular, tissue, and organismal levels remain largely unexplored. Thus, emerges a fundamental question connecting the study of sex differences and sex chromosome aneuploidy syndromes: How does sex chromosome constitution influence phenotype? Here, we focus on Turner syndrome (TS), associated with the 45,X karyotype, and its synergies with the study of sex differences. We review findings from evolutionary studies of the sex chromosomes, which identified genes that are most likely to contribute to phenotypes as a result of variation in sex chromosome constitution. We then explore strategies for investigating the direct effects of the sex chromosomes, and the evidence for specific sex chromosome genes impacting phenotypes. In sum, we argue that integrating the study of TS with sex differences offers a mutually beneficial alliance to identify contributions of the sex chromosomes to human development, health, and disease.     

Sex differences in lectin-induced interleukin-2 synthesis in aging rats

Several aspects of T cell-mediated immune responses decline with age, but it is not known how gender affects this decline. Using 3- and 26-month-old male and female Fischer 344 rats, we examined the effects of sex and age on four different immune events that normally decline during aging: antibody synthesis to a T-dependent antigen, lectin-induced proliferative responses, IL-2 synthesis, and natural killer activity. We found that all these responses decreased with age. Spleen cells from aged females had higher spontaneous, phytohemagglutinin (PHA), and concanavalin A (Con A)-induced proliferative responses, and a two-fold increase in IL-2 synthesis than aged males, although no differences in these responses were evident between young males and females. Both natural killer (NK) activity and the ability to generate plaque-forming cells to sheep erythrocytes (SRBC) declined with age, but there were no differences between males and females for these responses in either age group. These data indicate that sex-associated differences in IL-2 synthesis and spontaneous and lectin-induced proliferative responses that are not detected in young animals become evident with advancing age.     

Serum total IgE levels in a representative sample of a Greek population

The distribution of IgE in a large randomly stratified Greek population sample was determined in 1187 subjects (793 men and 394 women) aged between 20 and 60 years. Skin prick testing was performed and serum total IgE expressed in iu/ml was measured by Phadebas PRIST: the data are presented as the geometric mean. Subjects were classified as atopic (257 men, 118 women) and nonatopic (536 men, 276 women) according to the results of skin testing with various aeroallergens. At any age, atopic males (120.5 vs 38 iu/ml) and females (99.8 vs 29.3 iu/ml) had higher mean IgE levels, as compared to nonatopic subjects ( P <0.0001). In our adult nonatopic sample, IgE levels did not differ with age ( P >0.05). At any age, nonatopic males had higher (38 iu/ml) mean IgE levels than nonatopic females (29.3 iu/ml) ( P <0.05). The comparison of normal IgE values (nonatopic subjects) from this study with those reported by other investigators revealed that Greek adult males and females had higher IgE levels than populations from other nations. Our results represent the first report on reference values regarding serum total IgE in Greek adults.