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Dimorphic Nucleus (dimorphic + nucleus)

Distribution by Scientific Domains
Life Sciences66%

Selected Abstracts

Sex Differences and the Roles of Sex Steroids in Apoptosis of Sexually Dimorphic Nuclei of the Preoptic Area in Postnatal Rats

JOURNAL OF NEUROENDOCRINOLOGY, Issue 4 2009
S. Tsukahara
The brain contains several sexually dimorphic nuclei that exhibit sex differences with respect to cell number. It is likely that the control of cell number by apoptotic cell death in the developing brain contributes to creating sex differences in cell number in sexually dimorphic nuclei, although the mechanisms responsible for this have not been determined completely. The milieu of sex steroids in the developing brain affects sexual differentiation in the brain. The preoptic region of rats has two sexually dimorphic nuclei. The sexually dimorphic nucleus of the preoptic area (SDN-POA) has more neurones in males, whereas the anteroventral periventricular nucleus (AVPV) has a higher cell density in females. Sex differences in apoptotic cell number arise in the SDN-POA and AVPV of rats in the early postnatal period, and an inverse correlation exists between sex differences in apoptotic cell number and the number of living cells in the mature period. The SDN-POA of postnatal male rats exhibits a higher expression of anti-apoptotic Bcl-2 and lower expression of pro-apoptotic Bax compared to that in females and, as a potential result, apoptotic cell death via caspase-3 activation more frequently occurs in the SDN-POA of females. The patterns of expression of Bcl-2 and Bax in the SDN-POA of postnatal female rats are changed to male-typical ones by treatment with oestrogen, which is normally synthesised from testicular androgen and affects the developing brain in males. In the AVPV of postnatal rats, apoptotic regulation also differs between the sexes, although Bcl-2 expression is increased and Bax expression and caspase-3 activity are decreased in females. The mechanisms of apoptosis possibly contributing to the creation of sex differences in cell number and the roles of sex steroids in apoptosis are discussed. [source]

Sex differences in the level of Bcl-2 family proteins and caspase-3 activation in the sexually dimorphic nuclei of the preoptic area in postnatal rats

DEVELOPMENTAL NEUROBIOLOGY, Issue 13 2006
Shinji Tsukahara
Abstract In developing rats, sex differences in the number of apoptotic cells are found in the central division of the medial preoptic nucleus (MPNc), which is a significant component of the sexually dimorphic nucleus of the preoptic area, and in the anteroventral periventricular nucleus (AVPV). Specifically, male rats have more apoptotic cells in the developing AVPV, whereas females have more apoptotic cells in the developing MPNc. To determine the mechanisms for the sex differences in apoptosis in these nuclei, we compared the expression of the Bcl-2 family members and active caspase-3 in postnatal female and male rats. Western blot analyses for the Bcl-2 family proteins were performed using preoptic tissues isolated from the brain on postnatal day (PD) 1 (day of birth) or on PD8. In the AVPV-containing tissues of PD1 rats, there were significant sex differences in the level of Bcl-2 (female > male) and Bax (female < male) proteins, but not of Bcl-xL or Bad proteins. In the MPNc-containing tissues of PD8 rats, there were significant sex differences in the protein levels for Bcl-2 (female < male), Bax (female > male), and Bad (female < male), but not for Bcl-xL. Immunohistochemical analyses showed significant sex differences in the number of active caspase-3-immunoreactive cells in the AVPV on PD1 (female < male) and in the MPNc on PD8 (female > male). We further found that active caspase-3-immunoreactive cells of the AVPV and MPNc were immunoreactive for NeuN, a neuronal marker. These results suggest that there are sex differences in the induction of apoptosis via the mitochondrial pathway during development of the AVPV and MPNc. © 2006 Wiley Periodicals, Inc. J Neurobiol, 2006 [source]

Sex Differences and the Roles of Sex Steroids in Apoptosis of Sexually Dimorphic Nuclei of the Preoptic Area in Postnatal Rats

JOURNAL OF NEUROENDOCRINOLOGY, Issue 4 2009
S. Tsukahara
The brain contains several sexually dimorphic nuclei that exhibit sex differences with respect to cell number. It is likely that the control of cell number by apoptotic cell death in the developing brain contributes to creating sex differences in cell number in sexually dimorphic nuclei, although the mechanisms responsible for this have not been determined completely. The milieu of sex steroids in the developing brain affects sexual differentiation in the brain. The preoptic region of rats has two sexually dimorphic nuclei. The sexually dimorphic nucleus of the preoptic area (SDN-POA) has more neurones in males, whereas the anteroventral periventricular nucleus (AVPV) has a higher cell density in females. Sex differences in apoptotic cell number arise in the SDN-POA and AVPV of rats in the early postnatal period, and an inverse correlation exists between sex differences in apoptotic cell number and the number of living cells in the mature period. The SDN-POA of postnatal male rats exhibits a higher expression of anti-apoptotic Bcl-2 and lower expression of pro-apoptotic Bax compared to that in females and, as a potential result, apoptotic cell death via caspase-3 activation more frequently occurs in the SDN-POA of females. The patterns of expression of Bcl-2 and Bax in the SDN-POA of postnatal female rats are changed to male-typical ones by treatment with oestrogen, which is normally synthesised from testicular androgen and affects the developing brain in males. In the AVPV of postnatal rats, apoptotic regulation also differs between the sexes, although Bcl-2 expression is increased and Bax expression and caspase-3 activity are decreased in females. The mechanisms of apoptosis possibly contributing to the creation of sex differences in cell number and the roles of sex steroids in apoptosis are discussed. [source]

Disruption of brain development in male rats exposed prenatally to 5-bromo-2,-deoxyuridine

CONGENITAL ANOMALIES, Issue 4 2001
Makiko Kuwagata
ABSTRACT, Sprague-Dawley rats were treated intraperitoneally with 5-bromo-2,-deoxyuridine (BrdU) at 0,12.5 or 50 mg/kg/day on days 9 through 15 of gestation to evaluate the effects on development of the brain of offspring. Prenatal exposure to BrdU induced abnormal development of the brain; dilatation of the lateral ventricles in male offspring in the postnatal period. The ratio of the length of the longitudinal fissure to that of the cerebral cortex decreased in a dose-dependent manner in the embryonic period and thereafter. In 14-week-old male offspring exposed prenatally to BrdU at 50 mg/kg, the cortex layer of the cerebrum was thinner than that of the controls. Masculine sexual behavior was markedly impaired and the volume of the sexually dimorphic nucleus of the preoptic area (SDN-POA) was decreased in the 50 mg/kg group as compared with the controls. These results demonstrate that prenatal exposure to BrdU affected the development of the brain hi the prenatal and postnatal stages and reduced the volume of SDN-POA after puberty, resulting in a disruption of reproductive ability in male rats. [source]

Sex differences in the level of Bcl-2 family proteins and caspase-3 activation in the sexually dimorphic nuclei of the preoptic area in postnatal rats

DEVELOPMENTAL NEUROBIOLOGY, Issue 13 2006
Shinji Tsukahara
Abstract In developing rats, sex differences in the number of apoptotic cells are found in the central division of the medial preoptic nucleus (MPNc), which is a significant component of the sexually dimorphic nucleus of the preoptic area, and in the anteroventral periventricular nucleus (AVPV). Specifically, male rats have more apoptotic cells in the developing AVPV, whereas females have more apoptotic cells in the developing MPNc. To determine the mechanisms for the sex differences in apoptosis in these nuclei, we compared the expression of the Bcl-2 family members and active caspase-3 in postnatal female and male rats. Western blot analyses for the Bcl-2 family proteins were performed using preoptic tissues isolated from the brain on postnatal day (PD) 1 (day of birth) or on PD8. In the AVPV-containing tissues of PD1 rats, there were significant sex differences in the level of Bcl-2 (female > male) and Bax (female < male) proteins, but not of Bcl-xL or Bad proteins. In the MPNc-containing tissues of PD8 rats, there were significant sex differences in the protein levels for Bcl-2 (female < male), Bax (female > male), and Bad (female < male), but not for Bcl-xL. Immunohistochemical analyses showed significant sex differences in the number of active caspase-3-immunoreactive cells in the AVPV on PD1 (female < male) and in the MPNc on PD8 (female > male). We further found that active caspase-3-immunoreactive cells of the AVPV and MPNc were immunoreactive for NeuN, a neuronal marker. These results suggest that there are sex differences in the induction of apoptosis via the mitochondrial pathway during development of the AVPV and MPNc. © 2006 Wiley Periodicals, Inc. J Neurobiol, 2006 [source]

Intrauterine proximity to male fetuses affects the morphology of the sexually dimorphic nucleus of the preoptic area in the adult rat brain

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 5 2006
Minjuan Pei
Abstract Previous studies on polytocous rodents have revealed that the fetal intrauterine position influences its later anatomy, physiology, reproductive performance and behavior. To investigate whether the position of a fetus in the uterus modifies the development of the brain, we examined whether the structure of the sexually dimorphic nucleus of the preoptic area (SDN-POA) of rat brains accorded to their intrauterine positions. Brain sections of adult rats gestated between two male fetuses (2M) and between two female fetuses (2F) in the uterus were analysed for their immunoreactivity to calbindin-D28k, which is a marker of the SDN-POA. The SDN-POA volume of the 2M adult males was greater than that of the 2F adult males, whereas the SDN-POA volume of the 2M and 2F adult females showed no significant difference. This result indicated that contiguous male fetuses have a masculinizing effect on the SDN-POA volume of the male. To further examine whether the increment of SDN-POA volume in adulthood was due to exposure to elevated steroid hormones during fetal life, concentrations of testosterone and 17,-estradiol in the brain were measured with 2M and 2F fetuses during gestation, respectively. On gestation day 21, the concentrations of testosterone and 17,-estradiol in the brain were significantly higher in the 2M male rats as compared with the 2F male rats. The results suggested that there was a relationship between the fetal intrauterine position, hormone transfer from adjacent fetuses and the SDN-POA volume in adult rat brains. [source]

Sex Differences and the Roles of Sex Steroids in Apoptosis of Sexually Dimorphic Nuclei of the Preoptic Area in Postnatal Rats

JOURNAL OF NEUROENDOCRINOLOGY, Issue 4 2009
S. Tsukahara
The brain contains several sexually dimorphic nuclei that exhibit sex differences with respect to cell number. It is likely that the control of cell number by apoptotic cell death in the developing brain contributes to creating sex differences in cell number in sexually dimorphic nuclei, although the mechanisms responsible for this have not been determined completely. The milieu of sex steroids in the developing brain affects sexual differentiation in the brain. The preoptic region of rats has two sexually dimorphic nuclei. The sexually dimorphic nucleus of the preoptic area (SDN-POA) has more neurones in males, whereas the anteroventral periventricular nucleus (AVPV) has a higher cell density in females. Sex differences in apoptotic cell number arise in the SDN-POA and AVPV of rats in the early postnatal period, and an inverse correlation exists between sex differences in apoptotic cell number and the number of living cells in the mature period. The SDN-POA of postnatal male rats exhibits a higher expression of anti-apoptotic Bcl-2 and lower expression of pro-apoptotic Bax compared to that in females and, as a potential result, apoptotic cell death via caspase-3 activation more frequently occurs in the SDN-POA of females. The patterns of expression of Bcl-2 and Bax in the SDN-POA of postnatal female rats are changed to male-typical ones by treatment with oestrogen, which is normally synthesised from testicular androgen and affects the developing brain in males. In the AVPV of postnatal rats, apoptotic regulation also differs between the sexes, although Bcl-2 expression is increased and Bax expression and caspase-3 activity are decreased in females. The mechanisms of apoptosis possibly contributing to the creation of sex differences in cell number and the roles of sex steroids in apoptosis are discussed. [source]

Estrogen configures sexual dimorphism in the preoptic area of C57BL/6J and ddN strains of mice

THE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 17 2010
Chitose Orikasa
Abstract Immunohistochemistry using a calbindin D28k antibody revealed a marked sex difference in neuronal distribution in the central portion of the medial preoptic area in C57BL/6J and ddN strains of mice when the animals were sacrificed on D65 (D1 = the day of birth). Male mice had a distinct ellipsoidal cell aggregate, whereas females lacked such a structure. This sex difference was not observed in Nissl-stained sections. Co-localization of calbindin D28k and the neuron-specific nuclear protein NeuN confrmed that the cells in the aggregate were neurons. The aggregates were larger in males than in females in both strains. When observed on D65, males orchidectomized on D1 had smaller aggregates. However, daily injections of 2 ,g estradiol benzoate through D1,D5 as well as a single injection of 100 ,g testosterone propionate on D1 enlarged the aggregates in females, but a single injection of 100 ,g dihydrotestosterone on D1 had no effect on the female phenotype. Similar endocrine manipulations had no effects in adult animals of both sexes. Thus, the calbindin-immunoreactive cell aggregates in the preoptic area of C57BL/6J and ddN mice are homologous to the sexually dimorphic nucleus of the rat preoptic area in terms of the morphology and sex steroid-dependent organization. J. Comp. Neurol. 518:3618,3629, 2010. © 2010 Wiley-Liss, Inc. [source]