Amine oxidase in mice-sex differences and developmental aspects.
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Aging↗
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Drug-induced porphyrin biosynthesis. VII. Species, sex, and developmental differences in the generation of experimental porphyria.
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17-Ketosteroids↗
Predator-induced opioid and non-opioid mediated analgesia in young meadow voles: sex differences and developmental changes.
The present study examined developmental changes in the nociceptive responses of male and female meadow voles, Microtus pennsylvanicus, exposed to a garter snake, a natural predator of young voles. After 15 min of exposure to the presence of a garter snake, neonatal-juvenile voles (5-20 days of age) displayed naloxone (1.0 mg/kg)-sensitive opioid mediated analgesic responses, while after a brief 30-s exposure to the snake, voles displayed a higher amplitude, non-opioid analgesia that was insensitive to naloxone and blocked by the serotonin-1A (5-HT1A) agonist, 8-hydroxy-2-(di-n-propylamino)tetralin. The levels of opioid and non-opioid mediated analgesia declined during development as the threat presented by the snake decreased. Young female voles also displayed a significantly greater non-opioid, 5-HT1A sensitive analgesia than males, with no significant sex differences in the lower amplitude opioid analgesia. These results indicate that young (neonatal) meadow voles that are exposed to a naturally threatening stimulus display sexually dimorphic analgesic responses. These findings also illustrate the need to consider the ecological context when examining environmentally-induced analgesia.
8-Hydroxy-2-(di-n-propylamino)tetralin↗
Sex differences and developmental effects of manipulations of oxytocin on alloparenting and anxiety in prairie voles.
In adult animals, peptide hormones, including oxytocin and arginine vasopressin, have been implicated in both parental behavior and the modulation of anxiety. The purpose of this study was to examine the consequences of developmental manipulations of oxytocin for the later expression of alloparental behavior as well as behavioral responses to a novel environment, the elevated plus maze (EPM). Prairie voles (Microtus ochrogaster), a cooperatively breeding species, were selected for this study. On neonatal Day 1, pups received an ip injection of oxytocin or oxytocin antagonist, or were controls, receiving either saline or handling only. At 21 and approximately 60 days of age, each animal was tested for parental care toward novel stimulus pups. At approximately 67 days, an EPM test was administered. Control females at 60 days of age were more likely to attack pups and spent less time in the open arm of the EPM, both of which might reflect higher levels of anxiety in females than males. In males, neonatal treatment with oxytocin antagonist was associated with reductions in parental care, especially during the initial exposure to pups on Day 21. Female behavior was not significantly changed as a function of neonatal treatments. Findings to date implicate vasopressin in the behavioral changes in males, that in later life followed a single exposure to an oxytocin antagonist, and suggest caution in the clinical use of agents such as Atosiban, which may have the potential to influence infant development.
Animals↗
Developmental and sex differences in cadmium distribution and metallothionein induction and localization.
Age- and sex-related differences in hepatic and renal distribution of cadmium (Cd) and the effect of Cd injection (10 mumol/kg) on tissue zinc (Zn), copper (Cu) and metallothionein (MT) levels were investigated in 2- to 84-day old rats. Renal Cd accumulation increased with age of the animal. Sex differences in renal Cd accumulation were noted in young animals where the 2- and 8-day old males had significantly greater concentration than the females. There were no clear effects of Cd on renal Zn. Renal Cu levels, however, were elevated in the adults. The adult females contained about twice as much MT as the adult males. Cd treatment had no effect on renal MT levels of 8- to 84-day old animals but depressed the levels in 2-day old. Age-related increase in hepatic Cd accumulation was also found; the pattern was more clear cut in females than in males. In addition, in the females the hepatic Cd concentration was significantly higher than in the males. Cd-injection significantly increased hepatic Zn and MT concentrations only in weaned animals. While there were no sex differences in MT levels in the young animals, the weaned females had significantly more MT than the corresponding males. Immunohistochemical staining for MT showed positive staining in both cytoplasm and nuclei of the parenchymal cells. The number of MT-positive nuclei was dependent on the relative MT concentration of the liver. In spite of the intense nuclear staining in 2-day old controls and 84-day old Cd-injected rats, less than 1% of the hepatic MT was present in the nuclear fraction.(ABSTRACT TRUNCATED AT 250 WORDS)
Aging↗
Ontogeny and sexual differentiation of somatostatin biosynthesis and secretion in the hypothalamic periventricular-median eminence pathway.
The biosynthesis of somatostatin (SRIH) in the hypothalamic periventricular nucleus (PeN) is sexually differentiated in neonatal and adult rats by virtue of the organizational and activational actions, respectively, of sex steroid hormones. Little information exists, however, on the normal pattern of maturation of these neurones or on how the sexually differentiated biosynthesis may relate to ontogenetic changes in somatostatin secretion during the neonatal and pubertal periods of development. Hence in the present study we determined the postnatal developmental profile of SRIH mRNA and peptide levels in the PeN-median eminence (ME) pathway as well as SRIH secretion, using an acute explant preparation, from the day of birth, through puberty and into adulthood in male and female rats. The results demonstrate that: (1) developmental sex differences in SRIH biosynthesis in PeN neurones occurred in an orderly cascade with differences observed for mRNA expression at postnatal day 5, for peptide content in the perikarya at postnatal day 10 and for peptide content in the nerve terminal (ME) by postnatal day 25; (2) sex differences in SRIH release were not evident prior to postnatal day 40; and (3) the developmental profile of SRIH biosynthesis in PeN neurones is unique compared with other hypothalamic (ventromedial nucleus) and extrahypothalamic (parietal cortex) populations. Specific developmental changes in the biosynthetic and secretory activity of the hypothalamic SRIH PeN-ME pathway may have a functional importance in the maturation of hypothalamic SRIH pathways involved in the regulation of GH secretion.
Aging↗
PCR sexing and developmental rate differences in preimplantation mouse embryos fertilized and cultured in vitro.
A two-step polymerase chain reaction (PCR) assay was used to determine the sex of mouse preimplantation embryos obtained from oocytes fertilized and cultured in vitro, to investigate the differences in the developmental rates of mouse embryos according to the sex. All the in vitro developed embryos could be analyzed by this method. When the embryos were classified according to the time of morula to blastocyst transition as fast-intermediate- and slow-growing embryos, a significantly high percentage (78.0%) of the fast-developing embryos were identified as males; while a significantly lower percentage (42.5%) of slow-developing embryos were identified as males. The intermediate-developing embryos presented a sex ratio not significantly different from the total (57.5%). The deviation of sex ratio was further confirmed by embryo transfer experiment, where fast- and slow-developing embryos gave 76.2% and 25.7% male fetuses, respectively. We concluded that male mouse embryos fertilized and cultured in vitro develop faster than female embryos.
Animals↗
[Developmental changes and sex differences in judging weights addition between 5th and 6th graders].
The purpose of the present study is to examined developmental changes and sex differences in judging weights. Experimental groups were engaged in weights addition tasks and then given correct answers (correctional feedback). Four to six months later, both experimental and control groups were subjected to the same tasks. The individual range of reaction time in 6th graders is much wider than that in 5th graders and that the presentation of correctional feedback is more effective in 6th graders. These results suggest that 6th graders make more efforts in judging weights addition with logical and overall criteria. Both 6th male and 5th female students judge weight with more consistent confidence than both 5th male and 6th female students. These results suggest that male students come to judge weight with consistent confidence with age while female students do not, and that the social desirability, that is, "male will always hold their own opinion" seems to affect judging process.
Child↗
Potential neuronal mechanisms of estrogen actions in synaptogenesis and synaptic plasticity.
1. Studies conducted on the rat arcuate nucleus, an area involved in the development and control of LH and FSH secretion, have shown the existence of hormonally regulated developmental sex differences in synaptic patterns and estrogen-induced synaptic plasticity during adult life. Several questions raised by these findings are examined in this review: 2. The mechanisms of estrogen-regulated developmental synaptogenesis. These include the role of glycocalyx glycoproteins in neuronal membranes, neural cell adhesion molecules, and insulin-like growth factor I. 3. The relationship among circulating estrogen, gonadotropin levels, and hypothalamic synaptic plasticity. Recent evidence for the role of GABAergic and dopaminergic synaptic inputs and POMC projections from the arcuate nucleus to the GnRH cells is discussed. 4. The synaptologic basis of age-related failure of positive feedback. The role of the cumulative effect of repeated preovulatory synaptic retraction and reapplication cycles on sensescent constant estrus is analyzed.
Animals↗
Aromatase: neuromodulator in the control of behavior.
Estrogens are required for both the organization of the brain in early development and adult behavior. Two approaches have been used in our laboratory to study the behavioral role of brain aromatase. First, brain metabolism of testosterone (T) has been related to behavior in the same individual using a well established neuroendocrine model, the ring dove, in which estradiol-17 beta (E2) has specific effects on brain mechanisms of male behavior. Aromatase in preoptic area (POA) (a) has a high activity (Vmax) and strong substrate binding affinity (Km < 5 nM), (b) is regulated by both androgens and estrogens, and the type of regulation differs according to brain area, (c) is influenced by products of an endogenous inactivating pathway, 5 beta-reduction; 5 beta-dihydrotestosterone and other 5 beta-reduced metabolites appear to be non-genomic regulators of the brain aromatase. Preoptic aromatase activity is also influenced by photoperiod and socio-sexual stimuli. The codistribution of regulated aromatase activity and estrogen receptor cells is found to be T-dependent. Our second approach has been to relate the aromatase system to developmental sex differences in brain structure and behavior of the Mongolian gerbil. Neonatal gerbil aromatase is relatively active in the POA, but has a weaker T substrate-binding affinity (Km = 30 nM) than the dove. T acting via its metabolite, E2, masculinizes the sexually dimorphic area of the hypothalamus; the differentiating effect is asymmetric. We suggest that the regulation of the brain aromatase system may be lateralized during steroid-sensitive periods of development.
Animals↗
Reorganization of a telencephalic motor region during sexual differentiation and vocal learning in zebra finches.
Male zebra finches learn to produce a vocal pattern during a sensitive period of development, whereas females do not. The motor output of telencephalic song processing is RA (the robust nucleus of the archistriatum), a region containing a population of projection neurons that descend to the hindbrain (nXIIts, the tracheo-syringeal portion of the hypoglossal nerve nucleus). In turn, nXIIts neurons innervate the vocal organ (syrinx). Previous work shows that the number of RA neurons is monomorphic in fledgling males and females. RA neuron number in males does not change thereafter, but females show a substantial developmental loss of RA neurons. Because the developmental sex difference in RA neuron number implies a change in the number of projection neurons within RA, we have made injections of retrograde tracer into the hindbrain to measure the percentage of RA neurons that project to nXIIts as a function of age in females and vocal development in males. In juveniles of both sexes, we found that close to two-thirds of RA neurons project to nXIIts. However, the percentage of RA neurons projecting to nXIIts declined by 44% during female development, and by 14% during a specific stage of male vocal development (the transition from subsong to plastic song). These data indicate that in addition to regulation of RA neuron number, sexual differentiation and vocal learning correlate with a significant decrease in the amount of descending input to the vocal organ. The loss of projection neurons during vocal learning is surprising in light of the stability of RA neuron number in males, and our findings suggest that the behavioral transition from subsong to plastic song may involve a restricted period of RA neuron loss and replacement and/or axon rearrangement.
Acoustic Stimulation↗
Sex-specific developmental changes in amygdala responses to affective faces.
It is hypothesized that adolescent development involves a redistribution of cerebral functions from lower subcortical structures to higher regions of the prefrontal cortex to provide greater self-control over emotional behavior. We further hypothesized that this redistribution is likely to be moderated by sex-specific hormonal changes. To examine developmental sex differences in affective processing, 19 children and adolescents underwent fMRI while viewing photographs of faces expressing fear. Males and females differed in the pattern of their amygdala vs prefrontal activation during adolescent maturation. With age, females showed a progressive increase in prefrontal relative to amygdala activation in the left hemisphere, whereas males failed to show a significant age related difference. There appear to be sex differences in the functional maturation of affect-related prefrontal-amygdala circuits during adolescence.
Adolescent↗
The microcephaly-lymphoedema syndrome: report of an additional family.
Fourteen patients from six families have been reported in which microcephaly occurs in conjunction with lymphoedema, with no evidence of mental retardation or serious neurological disabilities. Chorioretinal dysplasia was noted in a small number of affected individuals. Inheritance was either autosomal dominant or X-linked and the question has been raised whether all these cases represent one entity or separate syndromes. We report the 7th family with two affected sibs of different sex. Developmental testing revealed normal to borderline intelligence associated with Attention Deficit Hyperactivity Disorder. The suggested mode of inheritance in this family is autosomal recessive. X-linked dominant inheritance cannot be ruled out, however, since the male was more severely involved than the female. We concur with previous authors that the association of microcephaly and lymphoedema is a distinct genetic syndrome and we propose to name this entity the 'microcephaly-lymphoedema syndrome'.
Female↗
Comment on delayed left-ear accuracy in dichotic listening.
Moulden and Persinger recently reported on the emergence of left-ear accuracy during childhood and adolescence. This commentary briefly discusses their findings with reference to previous studies that have reported on dichotic listening paradigms and, in particular, those in which a left-ear focus was used as a behavioral probe sensitive to developmental sex differences.
Auditory Perception↗
Sex-related differences in developmental rates of bovine embryos produced and cultured in vitro.
The classical concept of sex determination in mammals is that a Y chromosomal gene controls the development of the indifferent gonad into a testis. Subsequent divergence of sexual phenotypes is secondary to this gonadal determination. The most likely candidate gene is SRY (sex-determining region Y) in humans, and Sry in mouse. However, several lines of evidence indicate that sexual dimorphism occurs even before the indifferent gonad appears. Here we present evidence that bovine male embryos generally develop to more advanced stages than do females during the first 8 days after insemination in vitro. Corresponding relationships between both cell numbers and mitotic indices and sex were also seen. Although it is not clear whether this phenomenon involves factors originating before or after fertilization, these findings suggest that sex-related gene expression affects the development of embryos soon after activation of the embryonic genome and well before gonadal differentiation.
Animals↗
Sex differences in the developmental changes of GABAergic neurons in zebra finch song control nuclei.
Small neurons in a sexually dimorphic nucleus of the zebra finch, the robust nucleus of the archistriatum (RA), were immunoreactive for gamma-aminobutyric acid (GABA). This dimorphism arose from the sex differences in the development of the RA neurons. We examined whether neurons with GABA-like immunoreactivity (GABA-LI) undergo the same developmental changes as the cresyl-violet-stained neurons in the RA. Somata with GABA-LI from male finches became larger during development, while somata with GABA-LI from female finches became smaller, at a rate similar to that in the total population of RA neurons. However, there were marked sex differences in the development of the number of RA neurons with GABA-LI. In the female, neurons with GABA-LI were lost at a rate which was similar to the rate of loss of the total population of RA neurons. On the other hand, in the male, the number of neurons with GABA-LI increased transiently during the sensitive period of song learning, while the total number of RA neurons did not change. This transient increase may be related to the fact that only male birds learn their song during a sensitive period.
Animals↗
Sex differences in toddlers with autism spectrum disorders.
Although autism spectrum disorders (ASD) prevalence is higher in males than females, few studies address sex differences in developmental functioning or clinical manifestations. Participants in this study of sex differences in developmental profiles and clinical symptoms were 22 girls and 68 boys with ASD (mean age = 28 months). All children achieved strongest performance in visual reception and fine motor followed by gross motor and language functioning. Sex differences emerged in developmental profiles. Controlling for language, girls achieved higher visual reception scores than boys; boys attained higher language and motor scores and higher social-competence ratings than girls, particularly when controlling for visual reception. Longitudinal, representative studies are needed to elucidate the developmental and etiological significance of the observed sex differences.
Affect↗
Sex-linked differences in developmental potential of single blastomeres from in vitro-fertilized 2-cell stage mouse embryos.
Single blastomeres were isolated from 2-cell mouse embryos and analyzed for their sex using the partially deleted Y chromosome as a marker. Sex identification of 83% of the embryos was achieved with conventionally Giemsa-stained chromosome preparations. The other half-embryos were cultured individually and were transferred to pseudopregnant recipient females. The implantation rate was significantly higher in the male half-embryos. Although 6% of the half-embryos were male. The male half-embryos contained more blastomeres in the blastocyst stage than female ones. These facts suggests that the potential for the development of male half-embryos into fetuses is different from that of female half-embryos.
Animals↗