scholarly journals Acute Stress Differentially Affects Aromatase Activity in Specific Brain Nuclei of Adult Male and Female Quail

Endocrinology ◽  
2011 ◽  
Vol 152 (11) ◽  
pp. 4242-4251 ◽  
Author(s):  
Molly J. Dickens ◽  
Charlotte A. Cornil ◽  
Jacques Balthazart
Keyword(s):  
Reproductive Behavior ◽  
Acute Stress ◽  
Aromatase Activity ◽  
Brain Nuclei ◽  
Male And Female ◽  
Estrogen Production ◽  
Female Quail ◽  
Male Reproductive Behavior ◽  
The Individual ◽  
The Brain

The rapid and temporary suppression of reproductive behavior is often assumed to be an important feature of the adaptive acute stress response. However, how this suppression operates at the mechanistic level is poorly understood. The enzyme aromatase converts testosterone to estradiol in the brain to activate reproductive behavior in male Japanese quail (Coturnix japonica). The discovery of rapid and reversible modification of aromatase activity (AA) provides a potential mechanism for fast, stress-induced changes in behavior. We investigated the effects of acute stress on AA in both sexes by measuring enzyme activity in all aromatase-expressing brain nuclei before, during, and after 30 min of acute restraint stress. We show here that acute stress rapidly alters AA in the male and female brain and that these changes are specific to the brain nuclei and sex of the individual. Specifically, acute stress rapidly (5 min) increased AA in the male medial preoptic nucleus, a region controlling male reproductive behavior; in females, a similar increase was also observed, but it appeared delayed (15 min) and had smaller amplitude. In the ventromedial and tuberal hypothalamus, regions associated with female reproductive behavior, stress induced a quick and sustained decrease in AA in females, but in males, only a slight increase (ventromedial) or no change (tuberal) in AA was observed. Effects of acute stress on brain estrogen production, therefore, represent one potential way through which stress affects reproduction.

scholarly journals Cerebral and gonadal aromatase expressions are differently affected during sex differentiation of Pleurodeles waltl

2004 ◽  
Vol 33 (3) ◽  
pp. 717-727 ◽  
Author(s):  
Sandra Kuntz ◽  
Amand Chesnel ◽  
Stéphane Flament ◽  
Dominique Chardard
Keyword(s):  
Sex Differentiation ◽  
Temperature Sensitive ◽  
Aromatase Activity ◽  
Gonadal Differentiation ◽  
Aromatase Expression ◽  
Larval Stages ◽  
Exon 1 ◽  
The Individual ◽  
Pleurodeles Waltl ◽  
The Brain

In vertebrates, sex is determined essentially by two means, genetic factors located on sex chromosomes and epigenetic factors such as temperature experienced by the individual during development. Steroids, especially estrogens, are clearly involved in gonadal differentiation in non-mammalian vertebrates. In this regard, the expression of the estrogen-producing enzyme, aromatase, has been shown to be temperature-sensitive in species where temperature can reverse sex differentiation, especially in our model, the amphibian Pleurodeles waltl. We investigated here the regulation of aromatase expression in the brain during sex differentiation in Pleurodeles. We first isolated a brain isoform of aromatase mRNA which differs in its 5′ untranslated region from the isoform previously isolated from adult gonads. In adult Pleurodeles, the brain isoform is mainly expressed in brain tissue while the other isoform is gonad specific. Thus, regulation of aromatase expression in P. waltl could occur by alternative splicing of non-coding exon 1 as previously described in mammals. We then investigated aromatase expression in the brain of male and female larvae and found no differences with regard to sex. Measures of aromatase activity in the brain also showed no differences between sexes at larval stages whereas activity markedly increases in the ovary concomitant with the start of gonadal differentiation. These results support the hypothesis that aromatase could be a target of a temperature-sensitive sex-reversing effect in the gonads but not in the brain.

scholarly journals What are extreme environmental conditions and how do organisms cope with them?

2011 ◽  
Vol 57 (3) ◽  
pp. 363-374 ◽  
Author(s):  
John C. Wingfield ◽  
J. Patrick Kelley ◽  
Frédéric Angelier
Keyword(s):  
Environmental Conditions ◽  
Acute Stress ◽  
Extreme Environment ◽  
Target Cells ◽  
Extreme Conditions ◽  
Alpine Regions ◽  
The Individual ◽  
The Brain ◽  
Pituitary Adrenal Axis ◽  
Interaction With Receptors

Abstract Severe environmental conditions affect organisms in two major ways. The environment may be predictably severe such as in deserts, polar and alpine regions, or individuals may be exposed to temporarily extreme conditions through weather, presence of predators, lack of food, social status etc. Existence in an extreme environment may be possible, but then to breed or molt in addition can present major bottlenecks that have resulted in the evolution of hormone-behavior adaptations to cope with unpredictable events. Examples of hormone-behavior adaptations in extreme conditions include attenuated testosterone secretion because territoriality and excess courtship may be too costly when there is one opportunity to reproduce. The individual may even become insensitive to testosterone when target areas of the brain regulating reproductive behavior no longer respond to the hormone. A second example is reduced sensitivity to glucocorticoids following acute stress during the breeding season or molt that allows successful reproduction and/or a vital renewal of the integument to endure extreme conditions during the rest of the year. Reduced sensitivity could involve: (a) modulated response of the hypothalamo-pituitary-adrenal axis, (b) reduced sensitivity to high glucocorticoid levels, or (c) a combination of (a) and (b). Moreover, corticosteroid binding proteins (CBP) buffer responses to stress by reducing the movement of glucocorticoids into target cells. Finally, intracellular enzymes (11β-hydroxysteroid dehydrogenase and variants) can deactivate glucocorticoids entering cells thus reducing interaction with receptors. These mechanisms have important implications for climate change and increasing extremes of weather.

Possible mechanism for the first response to short captivity stress in the water frog, Rana esculenta

1996 ◽  
Vol 148 (2) ◽  
pp. 233-239 ◽  
Author(s):  
A Gobbetti ◽  
M Zerani
Keyword(s):  
Rana Esculenta ◽  
Prostaglandin E ◽  
Aromatase Activity ◽  
Male And Female ◽  
Water Frog ◽  
First Response ◽  
Prostaglandin F ◽  
Endocrine Mechanism ◽  
The Brain ◽  
Time Point

Abstract To clarify the endocrine mechanism involved in the short captivity stress in the water frog, Rana esculenta, the activity of 9-ketoreductase, the enzyme which converts prostaglandin E2 (PGE2) into prostaglandin F2α (PGF2α), and aromatase, which converts testosterone into oestradiol-17β, were studied. Adult male and female frogs were sacrificed 0, 1·5, 3, 6, 12, 24, 48, 72, 168 and 336 h after capture in the field. PGE2, PGF2α, progesterone, testosterone, oestradiol-17β and corticosterone plasma levels were detected by RIA at each time point. 9-Ketoreductase (conversion of [3H]PGE2 into [3H]PGF2α) and aromatase (conversion of [3H]testosterone into [3H]oestradiol-17β) activities in the brain, testis, ovary and interrenal were also determined at each time point. After capture, levels of plasma PGF2α increased (male: 228%; female: 288%) and PGE2 decreased (male: 68%; female: 81%) at 1·5 h, oestradiol-17β increased (male: 399%; female: 425%) and testosterone decreased (male: 87%; female: 83%) at 6 h, and corticosterone increased (male: 421%; female: 426%) at 72 h. 9-Ketoreductase activity in the brain was enhanced at 1·5 h after capture (male: 249%; female: 262%); aromatase activity increased at 6 h in the testis (261%), ovary (273%) and interrenal (male: 227%; female: 267%). These results indicate that short captivity stress could induce an increase in plasma PGF2α through activation of brain 9-ketoreductase. In turn, PGF2α might enhance the levels of circulating oestradiol-17β through activation of gonadal and interrenal aromatase. Journal of Endocrinology (1996) 148, 233–239

Environmental Stimuli Influence Oestrogen-Dependent Courtship Transitions and Brain Aromatase Activity in Male Ring Doves

Behaviour ◽  
1996 ◽  
Vol 133 (3-4) ◽  
pp. 199-219 ◽  
Author(s):  
R.E. Hutchison ◽  
G. Opromolla ◽  
J.B. Hutchison
Keyword(s):  
Reproductive Development ◽  
Reproductive Behaviour ◽  
Courtship Behaviour ◽  
Aromatase Activity ◽  
Male Courtship ◽  
Male And Female ◽  
Brain Aromatase ◽  
Reproductive Cycles ◽  
Ring Doves ◽  
The Brain

AbstractIn paired ring doves, Streptopelia risoria, male and female reproductive behaviour undergoes a series of synchronised transitions. The duration of each phase depends on the reproductive development of the pair. This study examines the effect of the environment in which behaviour is shown on both oestrogen-dependent courtship transitions and formation of oestrogen in the brain. The structuring of the cage environment had an immediate effect on transitions in male courtship behaviour. Males which were tested with females in a cage environment with a perch and a nest bowl (complex cage) displayed significantly less aggressive courtship and more nest-orientated behaviour than males tested with females in a cage environment without perch or nest bowl (simple cage). The response of males, which showed aggressive and nest-orientated courtship behaviour, to reproductively advanced females (abdominal length 1.4-1.6 cm) about to lay eggs or females in earlier stages of reproductive development (abdominal length 0.8-1.1 cm) did not differ initially. On the eighth day of 15-min daily tests, there was, however, an increase in aggressive courtship to females with smaller abdomens. This result suggests that male aggressiveness is more likely when the male and female reproductive cycles are not synchronised. We also tested whether environmental factors and the male's hormonal condition, which affect male courtship interactions, influence the formation of behaviourally effective oestrogen by aromatisation of testosterone in the brain. The aromatase activity was measured in the preoptic and anterior hypothalamic areas in relation to the time spent in interaction with females each day. Both intact and castrated males which interacted intermittently (15 min each day for 9 days) had higher preoptic aromatase activity than males which interacted continuously with females. The males which had high brain aromatase activity and had interacted intermittently with females were considered to represent the initial stages of the cycle. We conclude that cage environment and female reproductive condition influence the course of courtship interactions. Oestrogen formation in the male brain is affected by the type of interaction.

scholarly journals Relationships between rapid changes in local aromatase activity and estradiol concentrations in male and female quail brain

2014 ◽  
Vol 65 (2) ◽  
pp. 154-164 ◽  
Author(s):  
M.J. Dickens ◽  
C. de Bournonville ◽  
J. Balthazart ◽  
C.A. Cornil
Keyword(s):  
Aromatase Activity ◽  
Male And Female ◽  
Female Quail ◽  
Rapid Changes

scholarly journals Aromatase Is Increased in Astrocytes in the Presence of Elevated Pressure

Endocrinology ◽  
2011 ◽  
Vol 152 (1) ◽  
pp. 207-213 ◽  
Author(s):  
J. W. Gatson ◽  
J. W. Simpkins ◽  
K. D. Yi ◽  
A. H. Idris ◽  
J. P. Minei ◽  
...  
Keyword(s):  
Brain Function ◽  
Elevated Pressure ◽  
Aromatase Activity ◽  
C6 Cells ◽  
Rat Glioma ◽  
Glioma C6 ◽  
Cortical Astrocytes ◽  
Estrogen Production ◽  
The Brain ◽  
Increased Pressure

Abstract After traumatic brain injury (TBI), a progressive injury and death of neurons and glia leads to decreased brain function. Endogenous and exogenous estrogens may protect these vulnerable cells. In this study, we hypothesized that increased pressure leads to an increase in aromatase expression and estrogen production in astrocytes. In this study, we subjected rat glioma (C6) cells and primary cortical astrocytes to increased pressure (25 mm Hg) for 1, 3, 6, 12, 24, 48, and 72 h. Total aromatase protein and RNA levels were measured using Western analysis and RT-PCR, respectively. In addition, we measured aromatase activity by assaying estrone levels after administration of its precursor, androstenedione. We found that increased pressure applied to the C6 cells and primary cortical astrocytes resulted in a significant increase in both aromatase RNA and protein. To extend these findings, we also analyzed aromatase activity in the primary astrocytes during increased pressure. We found that increased pressure resulted in a significant (P < 0.01) increase in the conversion of androstenedione to estrone. In conclusion, we propose that after TBI, astrocytes sense increased pressure, leading to an increase in aromatase production and activity in the brain. These results may suggest mechanisms of brain estrogen production after increases in pressure as seen in TBI patients.

5β-Reductase activity in the brain and cloacal gland of male and female embryos in the Japanese quail (Coturnix coturnix japonica)

1984 ◽  
Vol 102 (1) ◽  
pp. 77-81 ◽  
Author(s):  
J. Balthazart ◽  
M. A. Ottinger
Keyword(s):  
Reductase Activity ◽  
Young Male ◽  
Testosterone Metabolism ◽  
Male And Female ◽  
Coturnix Coturnix ◽  
Female Quail ◽  
In Vitro Technique ◽  
The Brain ◽  
Cloacal Gland

ABSTRACT Testosterone metabolism was studied by an in-vitro technique in the brain and cloacal gland of young male and female quail at different ages ranging from 7 days of incubation to 2 days after hatching. Very active metabolism, leading almost exclusively to the production of 5β-reduced compounds, was observed. 5β-Reductase activity remained high throughout the incubation period in the hypothalamus, decreased around the time of hatching in the cerebellum and decreased progressively between days 7 and 15 of incubation in the cloacal gland. These changes could be involved in the control of sexual differentiation: the high 5β-reductase in the brain possibly protects males from being behaviourally demasculinized by their endogenous testosterone while the decreasing 5β-reductase in the cloacal gland would progressively permit the masculinization of that structure. J. Endocr. (1984) 102, 77–81

Fit Vs Faint: Assessing Work Causation in “Idiopathic Fall” Cases

2014 ◽  
Vol 19 (5) ◽  
pp. 3-12
Author(s):  
Lorne Direnfeld ◽  
David B. Torrey ◽  
Jim Black ◽  
LuAnn Haley ◽  
Christopher R. Brigham
Keyword(s):  
Blood Flow ◽  
Electrical Activity ◽  
Loss Of Consciousness ◽  
Brain Electrical Activity ◽  
Medical Terminology ◽  
Scientific Analysis ◽  
Medical Causation ◽  
The Individual ◽  
The Brain ◽  
Current Science

Abstract When an individual falls due to a nonwork-related episode of dizziness, hits their head and sustains injury, do workers’ compensation laws consider such injuries to be compensable? Bearing in mind that each state makes its own laws, the answer depends on what caused the loss of consciousness, and the second asks specifically what happened in the fall that caused the injury? The first question speaks to medical causation, which applies scientific analysis to determine the cause of the problem. The second question addresses legal causation: Under what factual circumstances are injuries of this type potentially covered under the law? Much nuance attends this analysis. The authors discuss idiopathic falls, which in this context means “unique to the individual” as opposed to “of unknown cause,” which is the familiar medical terminology. The article presents three detailed case studies that describe falls that had their genesis in episodes of loss of consciousness, followed by analyses by lawyer or judge authors who address the issue of compensability, including three scenarios from Arizona, California, and Pennsylvania. A medical (scientific) analysis must be thorough and must determine the facts regarding the fall and what occurred: Was the fall due to a fit (eg, a seizure with loss of consciousness attributable to anormal brain electrical activity) or a faint (eg, loss of consciousness attributable to a decrease in blood flow to the brain? The evaluator should be able to fully explain the basis for the conclusions, including references to current science.

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