Distribution of vasopressin in the brain of the eusocial naked mole-rat

Naked mole-rats are eusocial rodents that live in large subterranean colonies in which one queen breeds with one to three males. All other animals are nonbreeding subordinates. The external features of male and female subordinates, including their genitalia, are remarkably monomorphic, as is their behavior. Because vasopressin (VP) is associated with social behaviors and sex differences in other species, its distribution in naked mole-rats was of interest. We used immunohistochemistry to examine VP in the brains of subordinate and breeding naked mole-rats of both sexes. As in other mammals, VP-immunoreactive (-ir) somata were found in the paraventricular (PVN) and supraoptic nuclei (SON) and VP-ir projections from these nuclei ran through the internal and external zone of the median eminence. However, naked mole-rats had very few VP-ir cells in the bed nucleus of the stria terminalis (BST) and none in the suprachiasmatic nucleus (SCN); the extensive network of fine-caliber VP-ir fibers usually seen in projection sites of the BST and SCN were also absent. Equally unexpected was the abundance of large-caliber VP-ir fibers in the dorsomedial septum. VP immunoreactivity was generally similar in all groups, with the exception of VP-ir cell number in the dorsomedial hypothalamus (DMH). Breeders had a population of labeled cells in the DMH that was absent, or nearly absent, in subordinates. Future studies on the function of VP in these areas are needed to determine how the atypical distribution of VP immunoreactivity relates to eusociality and the unusual physiology of naked mole-rats.     

Gender-related neuronal and smooth muscle damage of guinea pig isolated urinary bladder from anoxia-glucopenia and reperfusion injury and its relationship to glycogen content

AIMS: To investigate the effects of anoxia and glucopenia (A-G) on both male and female guinea pig urinary bladder. METHODS: In whole bladders superfused with oxygenated Krebs' solution, intrinsic nerves underwent electrical field stimulation (EFS) and smooth muscle stimulated with carbachol, ATP, and high potassium. The effect of 1, 2, or 3 hr A-G on the contractile response and the ensuing recovery in Krebs' solution, was monitored. Glycogen content in male and female urinary bladders was also measured. RESULTS: Under different stimuli male urinary bladder proved to contract more efficiently than female organ. After 1 hr A-G the EFS response of male urinary bladder was virtually abolished and returned to 60% of control response in the recovery phase; in female bladder the EFS responses fully recovered during the reperfusion phase. Full recovery of the response to carbachol, ATP, and high potassium stimulations was observed in both genders. A-G had to be extended to 2 hr to cause smooth muscle impairment (higher in male than in female) and a neuronal impairment in female urinary bladders. When 2-deoxyglucose (2-DG), an inhibitor of glycolysis, was added during 1 hr A-G, both neuronal and smooth muscle damages were significantly enhanced in male, as well as, though to a lesser extent, in female bladder. A significantly higher glycogen content was observed in female as compared to male bladders, which was inversely related with the duration of exposure to A-G. CONCLUSIONS: The higher resistance of female urinary bladder to A-G/reperfusion, can be partly ascribed to the higher glycogen content.     

Low-level light stimulates excisional wound healing in mice

BACKGROUND: Low levels of laser or non-coherent light, termed low-level light therapy (LLLT) have been reported to accelerate some phases of wound healing, but its clinical use remains controversial. METHODS: A full thickness dorsal excisional wound in mice was treated with a single exposure to light of various wavelengths and fluences 30 minutes after wounding. Wound areas were measured until complete healing and immunofluorescence staining of tissue samples was carried out. RESULTS: Wound healing was significantly stimulated in BALB/c and SKH1 hairless mice but not in C57BL/6 mice. Illuminated wounds started to contract while control wounds initially expanded for the first 24 hours. We found a biphasic dose-response curve for fluence of 635-nm light with a maximum positive effect at 2 J/cm(2). Eight hundred twenty nanometer was found to be the best wavelength tested compared to 635, 670, and 720 nm. We found no difference between non-coherent 635+/-15-nm light from a lamp and coherent 633-nm light from a He/Ne laser. LLLT increased the number of alpha-smooth muscle actin (SMA)-positive cells at the wound edge. CONCLUSION: LLLT stimulates wound contraction in susceptible mouse strains but the mechanism remains uncertain.     

Brain networks subserving the extraction of sentence information and its encoding to memory

Sentences are the primary means by which people communicate information. The information conveyed by a sentence depends on how that sentence relates to what is already known. We conducted an fMRI study to determine how the brain establishes and retains this information. We embedded sentences in contexts that rendered them more or less informative and assessed which functional networks were associated with comprehension of these sentences and with memory for their content. We identified two such networks: A frontotemporal network, previously associated with working memory and language processing, showed greater activity when sentences were informative. Independently, greater activity in this network predicted subsequent memory for sentence content. In a separate network, previously associated with resting-state processes and generation of internal thoughts, greater neural activity predicted subsequent memory for informative sentences but also predicted subsequent forgetting for less-informative sentences. These results indicate that in the brain, establishing the information conveyed by a sentence, that is, its contextually based meaning, involves two dissociable networks, both of which are related to processing of sentence meaning and its encoding to memory.     

Gender differences in the induction of chromosomal aberrations and gene mutations in rodent germ cells

Germ cell mutagenicity testing provides experimental data to quantify genetic risk for exposed human populations. The majority of tests are performed with exposure of males, and female data are relatively rare. The reason for this paucity lies in the differences between male and female germ cell biology. Male germ cells are produced throughout reproductive life and all developmental stages can be ascertained by appropriate breeding schemes. In contrast, the female germ cell pool is limited, meiosis begins during embryogenesis and oocytes are arrested over long periods of time until maturation processes start for small numbers of oocytes during the oestrus cycle in mature females. The literature data are reviewed to point out possible gender differences of germ cells to exogenous agents such as chemicals or ionizing radiation. From the limited information, it can be concluded that male germ cells are more sensitive than female germ cells to the induction of chromosomal aberrations and gene mutations. However, exceptions are described which shed doubt on the extrapolation of experimental data from male rodents to the genetic risk of the human population. Furthermore, the female genome may be more sensitive to mutation induction during peri-conceptional stages compared to the male genome of the zygote. With few exceptions, germ cell experiments have been carried out under high acute exposure to optimize the effects and to compensate for the limited sample size in animal experiments. Human exposure to environmental agents, on the other hand, is usually chronic and involves low doses. Under these conditions, gender differences may become apparent that have not been studied so far. Additionally, data are reviewed that suggest a false impression of safety when responses are negative under high acute exposure of male rodents while a mutational response is induced by low chronic exposure. The classical (morphological) germ cell mutation tests are not performed anymore because they are animal and time consuming. Nevertheless, information is needed to place genetic risk extrapolations on more solid grounds and thereby to prevent an increased genetic burden to future generations. It is pointed out that modern molecular methodologies are available now to experimentally address the open questions.     

Sex Differences in Memory for Sexually-Relevant Information

The present study was conducted in an attempt to examine potential differences between men and women in memory for sexually relevant information. A total of 77 undergraduate students (31 men, 46 women) read a sexual story and completed memory tasks in response to the story. Based on previous research, we hypothesized that differences would exist between men and women for different types of sexual information and we hoped to understand whether specific variables (sexual experiences, sexual functioning, and reactions to the sexual story) could explain such differences. Men were more likely to remember erotic or explicit details of the story, whereas women were more likely to remember love and emotional bonding details of the story. Additionally, women were more likely to recall information referencing the characters in the story. Results from regression analyses indicated that sexual desire and satisfaction were related to differences in recall and recognition of the love and emotional bonding aspects of the story, and that frequency of sexual intercourse was related to differences in the recall of erotic or explicit details of the story. The significant results obtained in this study correspond to previously established sex differences in memory for sexual information.     

Ethnic-racial differences in feelings of embarrassment associated with binge eating and fear of losing control

OBJECTIVE: Limited research exists on ethnic-racial differences in the objective and subjective experiences of binge eating among women in the United States. The present study examined binge eating related psychopathology in a nationally representative sample of White, Black, Native American, Asian, and Hispanic women. METHOD: A subsample of 5,726 women between the ages of 19 and 27 years were selected from the National Longitudinal Study of Adolescent Health. RESULTS: Ethnic-racial differences in binge eating related psychopathology were found. Asians and Native Americans were more likely than Whites to report they would feel embarrassment related to binge eating. Hispanics were more likely than Whites and Blacks to report they would be afraid to start eating for fear of losing control. CONCLUSION: Findings suggest that the affective dimensions associated with binge eating are differentially represented among ethnic-racial groups. Implications for treatment and prevention programs are discussed.     

Determinants of smoking among adolescents in the Southern Cape-Karoo region, South Africa

Tobacco control programmes in multi-ethnic societies must take into account ethnic differences in the determinants of smoking. The I-Change Model, an extension of the Theory of Planned Behaviour, was used to investigate the factors related to smoking among a sample of 3378 Black African, Coloured and White, monthly and non-monthly smokers in the Southern Cape-Karoo Region, South Africa. Across the ethnic groups, non-monthly smokers reported a more positive attitude towards non-smoking, social influences that were more supportive of non-smoking, higher self-efficacy in stressful, routine and social situations, greater intention not to smoke in the next year and lower levels of depressive mood and risk behaviour. Regression analyses suggested that the weight of these determinants may differ in predicting monthly smoking among the ethnic groups. Black African students may benefit from the development of attitudinal cognitions and coping skills to counter peer influence. Coloured students also require skills to resist peer influence. White students require coping skills in stressful and social situations. Although there are more common than unique determinants of smoking among South African adolescents, further research is needed to understand the influence of differing social, economic and cultural contexts on smoking onset.     

Similarities and reciprocal influences in eating behavior within sibling pairs: a longitudinal study

The present study investigated similarities and reciprocal influences in emotional, external and restrained eating in adolescent siblings, and the moderating role of sex and quality of relationship. A total of 415 sibling pairs (aged 13-16 years) participated in this two-wave one-year longitudinal study. Analyses were conducted by means of Structural Equation Modeling. Cross-sectional findings demonstrated that siblings are moderately similar in their eating behavior. Longitudinal findings showed that the younger siblings exert a small influence on the emotional and external eating behavior of the older siblings. No support was found for the older siblings affecting the younger siblings in their eating behavior. Furthermore, no sex differences were found in the associations between sibling eating behaviors within and over time. However, we did find a moderating effect for the quality of the relationship concerning similarities in emotional eating. Future research focusing on various sociocultural influences on adolescents' eating behaviors should also include younger siblings.     

Sex Differences in WISC-III Profiles of Children with High-functioning Pervasive Developmental Disorders

Using the Japanese version of the Wechsler Intelligence Scale for Children-Third Edition (WISC-III), 26 girls with high-functioning (IQ ≥ 70) pervasive developmental disorders (HFPDD) (mean age, 8.2 years) were compared with 116 boys with HFPDD (mean age, 9.0 years). Compared with the boys, the girls scored significantly higher on the Processing Speed index, Coding, and Symbol Search, but scored significantly lower on Block Design. Although both groups showed weakness on Comprehension in the verbal domain, the girls’ subtest profile in the performance domain was relatively even and significantly different from the boys’, which was characterized by a peak on Block Design. Such differences should be replicated, and possible behavioral, neurological, and genetic links to these sex differences should be clarified.