Regulation of female brain aromatase activity during the reproductive cycle of the dove

ABSTRACT Oestrogen is formed in the female dove brain. The aim of this study was to determine whether (a) the catalytic properties of the brain aromatase are similar to the ovarian enzyme and (b) aromatase activity in the female brain changes during the reproductive cycle and is influenced by steroids and environmental stimuli. The results show that female preoptic aromatase has a higher substrate affinity than the enzyme in ovarian follicles (apparent Km: preoptic area, 7 nmol/l; ovarian follicles, 29 nmol/l), but a lower activity in the preoptic area (Vmax: preoptic area, 290 fmol/mg tissue per h; ovarian follicles, 843 fmol/mg tissue per h). In intact females with developing follicles, oestradiol-17β formation was higher in the posterior hypothalamus than the preoptic area. Females in a later stage of reproductive development (yolked follicles) had a different distribution of oestrogen formation with increased aromatase activity in the preoptic area. Preoptic and posterior hypothalamic aromatase activity of females paired with males for 10 days was positively correlated (r = 0·84, P = 0·0001; r = 0·75, P = 0·001 respectively) with ovarian development. Females with undeveloped ovaries which interacted with males had higher preoptic aromatase activity than visually isolated females with similar ovarian development, suggesting that behavioural stimuli have direct effects on brain aromatase activity which are independent of the ovary. Oestradiol benzoate treatment increased preoptic and posterior hypothalamic aromatase activity in intact and ovariectomized females, and testosterone propionate treatment increased anterior hypothalamic aromatase activity, but did not affect other areas, indicating that the distribution of induced aromatase activity is steroid-specific. Oestrogen treatment in ovariectomized or intact females did not replicate the maximal hypothalamic aromatase activity seen when the ovary contained yolked follicles. We conclude that brain aromatase activity is related directly to ovarian condition during the reproductive cycle of the female dove. As in the male, steroids have a role in the regulation of oestrogen formation in the female hypothalamus; behavioural stimuli are also likely to be involved in the control of the brain enzyme. Journal of Endocrinology (1992) 134, 385–396

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Effects of photoperiod on formation of oestradiol-17β in the dove brain

Journal of Endocrinology ◽

10.1677/joe.0.1090371 ◽

1986 ◽

Vol 109 (3) ◽

pp. 371-377 ◽

Cited By ~ 18

Author(s):

J. B. Hutchison ◽

Th. Steimer ◽

P. Jaggard

Keyword(s):

Preoptic Area ◽

Direct Action ◽

Specific Effect ◽

Short Photoperiod ◽

Aromatase Activity ◽

Vocal Behaviour ◽

Brain Aromatase ◽

Hormone Sensitive ◽

Short Days

ABSTRACT The effects of photoperiod and castration on brain aromatase activity have been examined using an in-vitro radioassay. Formation of oestradiol-17β was lower in the preoptic area of male Barbary doves on a short daylength (6 h light: 18 h darkness) than in males on a long daylength (14 h light: 10 h darkness). This was a specific effect of photoperiod which did not influence aromatase activity in the anterior or posterior hypothalamic areas, and was not accompanied by changes in hormone-sensitive vocal behaviour. Production of 5β-dihydrotestosterone, 5β-androstane-3α,17β-diol and 5α-dihydrotestosterone by the preoptic area did not differ between birds on long or short days. Therefore, a short photoperiod does not appear to influence other pathways of androgen metabolism. In contrast to the effects of photoperiod, castration reduced oestradiol formation in both preoptic and hypothalamic areas. Intramuscular injection of testosterone propionate (TP) in intact males on short days did not restore the pattern of distribution of aromatase activity seen in males on long days. Preoptic aromatase activity was, however, restored by TP in castrated birds. We conclude that a short photoperiod influences both the activity of aromatase and the inductive effect of testosterone on enzyme activity in the preoptic area, which is known to be associated with the behavioural action of oestrogen in the dove. Photoperiod is likely to act both through changes in circulating androgen and by a direct action on preoptic cells. J. Endocr. (1986) 109, 371–377

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

Behaviour ◽

10.1163/156853996x00116 ◽

1996 ◽

Vol 133 (3-4) ◽

pp. 199-219 ◽

Cited By ~ 7

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.

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Ligulaintestinalis infection is associated with alterations of both brain and gonad aromatase expression in roach (Rutilusrutilus)

Journal of Helminthology ◽

10.1017/s0022149x10000660 ◽

2010 ◽

Vol 85 (3) ◽

pp. 339-344 ◽

Cited By ~ 4

Author(s):

C. Boulange-Lecomte ◽

P. Geraudie ◽

J. Forget-Leray ◽

M. Gerbron ◽

C. Minier

Keyword(s):

Quantitative Polymerase Chain Reaction ◽

Gonadosomatic Index ◽

Gonad Development ◽

Endocrine Disrupting Compounds ◽

Infected Fish ◽

Aromatase Activity ◽

Aromatase Expression ◽

Brain Aromatase ◽

Functional Relevance ◽

The Brain

AbstractThe tapeworm Ligulaintestinalis commonly infests roach (Rutilusrutilus) and is responsible for the inhibition of gonad development. In order to better understand the effect of the plerocercoid on fish physiology, and to discriminate parasitization effects from those of endocrine-disrupting compounds (EDC), Cyp19b and Cyp19a aromatase expression was investigated by real-time quantitative polymerase chain reaction (PCR) in brain and gonads of ligulosed roach, caught from a reference site. Data were compared to reproductive and endocrine endpoints previously reported in a larger cohort study (including the sampled population of the present one), such as gonadosomatic index, Fulton index, gonadal histology, plasma sex steroid levels and brain aromatase activity. A decrease in Cyp19b expression in the brain of infected fish was demonstrated, in agreement with the reduction of aromatase activity previously described. In contrast, Cyp19a expression in the gonads appeared to be enhanced in ligulosed fish, in accordance with the presence of immature but differentiated sexual tissues. Together these results show that: (1) L. intestinalis infestation results in an alteration of aromatase expression which, in particular, may have profound effects on the fish brain; and (2) L. intestinalis infection must be considered as a major confounding factor in ecotoxicological studies using aromatase expression as an EDC biomarker. Moreover, the concordance between activity and expression – investigated for the first time in the same population – gives a functional relevance to the transcript aromatase dosage in the brain. Finally, quantitative PCR was confirmed as a sensitive approach, enabling aromatase status to be defined in the poorly developed gonads of ligulosed individuals.

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Rapid Control of Brain Aromatase Activity by Glutamatergic Inputs

Endocrinology ◽

10.1210/en.2005-0845 ◽

2006 ◽

Vol 147 (1) ◽

pp. 359-366 ◽

Cited By ~ 116

Author(s):

Jacques Balthazart ◽

Michelle Baillien ◽

Gregory F. Ball

Keyword(s):

Brain Function ◽

Time Course ◽

Aminobutyric Acid ◽

Aromatase Activity ◽

Brain Aromatase ◽

Rapid Control ◽

Rapid Changes ◽

Glutamate Agonists ◽

Membrane Effects ◽

The Brain

Estrogens derived from the neural aromatization of testosterone play a key role in the activation of male sexual behavior in many vertebrates and have now been recognized to have rapid membrane effects on brain function. Such changes in aromatase activity and hence in local estrogen concentrations could rapidly modulate behavioral responses. We show here that there is a very rapid (within minutes) decrease in aromatase activity in quail hypothalamic explants exposed to treatments affecting intracellular Ca2+ concentrations, such as the addition of glutamate agonists (kainate, α-amino-3-hydroxymethyl-4-isoxazole propionic acid, and, to a much lesser extent, N-methyl-d-aspartate), but not of γ-aminobutyric acid. The kainate effects, which reduce aromatase activity by 25–50%, are observed within 5 min, are completely blocked in explants exposed to specific kainate antagonists (6-cyano-7-nitroquinoxaline-2,3-dione disodium or 1,2,3,4-tetrahydro-6-nitro-2,3-dioxo-benzo[f]quinoxaline-7-sulfonamide disodium), and are also rapidly reversible when effectors are washed out. Together, these data support the idea that the synthesis of estrogen can be rapidly regulated in the brain, thus producing rapid changes in local estrogen bioavailability that could rapidly modify brain function with a time course similar to what has previously been described for neurotransmitters and neuromodulators.

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Effects on Plasma Luteinizing Hormone Levels of Microinjection of Noradrenaline and Adrenaline into the Septo-Preoptic Area of the Brain of the Ovariectomized Ewe: Changes with Season and Chronic Oestrogen Treatment

Journal of Neuroendocrinology ◽

10.1111/j.1365-2826.1992.tb00356.x ◽

1992 ◽

Vol 4 (1) ◽

pp. 131-141 ◽

Cited By ~ 16

Author(s):

Christopher J. Scott ◽

James T. Cumminst ◽

Iian J. Clarke

Keyword(s):

Luteinizing Hormone ◽

Preoptic Area ◽

Oestrogen Treatment ◽

Hormone Levels ◽

The Brain ◽

Noradrenaline And Adrenaline

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Reproductive effects of placing micro-implants of melatonin in the mediobasal hypothalamus and preoptic area in rams

Journal of Endocrinology ◽

10.1677/joe.0.1320201 ◽

1992 ◽

Vol 132 (2) ◽

pp. 201-215 ◽

Cited By ~ 63

Author(s):

G. A. Lincoln ◽

K.-I. Maeda

Keyword(s):

Reproductive Cycle ◽

Preoptic Area ◽

Plasma Concentrations ◽

Mediobasal Hypothalamus ◽

Reproductive Effects ◽

Long Day ◽

Reproductive Axis ◽

Micro Implants ◽

The Brain ◽

Short Days

ABSTRACT The reproductive effects of placing micro-implants of melatonin in the mediobasal hypothalamus (MBH) and preoptic area (POA) were monitored in Soay rams. Groups of animals were initially conditioned to alternating 16 weekly periods of long days (16 h light:8 h darkness; 16L:8D) and short days (8L:16D) for at least 9 months to entrain the seasonal reproductive cycle. All experiments were then initiated at 10 weeks under long days when the animals were sexually inactive. In experiment 1, rams were exposed to short days for 14 weeks or maintained on long days to illustrate the photoperiodically induced re-activation and regression of the reproductive axis. In experiments 2–4, rams received micro-implants of melatonin in the MBH or POA, or received control treatments (sham-operated or no surgery) for 12–14 weeks while maintained on long days (total of 12 animals/treatment). The melatonin implants consisted of 22-gauge stainless-steel cannulae with melatonin fused inside the tip and were placed bilaterally in the brain. Incubation of the implants in Tricine-buffered saline (pH 8·0) at 37 °C showed that the release rate of melatonin was relatively constant after an initial peak in week 1 (means ± s.e.m.: 3·42 ± 0·43 μg/24 h). Rams with melatonin implants placed in the MBH, but not in the POA, showed a consistently earlier re-activation of the reproductive axis compared with the control animals in all three experiments (12/12 for MBH vs 2/12 for POA). The mean time to maximum testicular diameter was 12·2 ± 0·9, 21·6 ± 1·8 and 22·3 ± 1·2 weeks for the MBH, POA and combined control groups respectively (MBH vs control, P < 0·01; analysis of variance). The premature growth of the testes in the MBH group was associated with an earlier increase in the blood plasma concentrations of FSH and testosterone, and the appearance of the sexual skin coloration. Removal of the implants resulted in a decline in all reproductive parameters. The melatonin treatments did not cause a detectable increase in the peripheral concentrations of melatonin, or affect the diurnal rhythm in melatonin which reflected the long-day photoperiod. When implants containing 125I-labelled melatonin were introduced into the brain the associated radioactivity was localized to within 1 mm of the implants. The overall results demonstrate that the constant administration of melatonin into the MBH blocks the effect of the endogenous long-day melatonin signal and induces gonadal redevelopment. This provides the first evidence that melatonin acts within or close to the MBH to relay effects of photoperiod and influence the timing of the reproductive cycle in the ram. Journal of Endocrinology (1992) 132, 201–215

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Estrogen biosynthesis in endometriosis: molecular basis and clinical relevance

Journal of Molecular Endocrinology ◽

10.1677/jme.0.0250035 ◽

2000 ◽

Vol 25 (1) ◽

pp. 35-42 ◽

Cited By ~ 97

Author(s):

SE Bulun ◽

KM Zeitoun ◽

K Takayama ◽

H Sasano

Keyword(s):

Clinical Relevance ◽

Prostaglandin E ◽

Aromatase Activity ◽

Normal Endometrium ◽

Feedback Cycle ◽

Brain Aromatase ◽

Molecular Aberrations ◽

Estrogen Biosynthesis ◽

The Brain

Conversion of C(19) steroids to estrogens is catalyzed by aromatase in human ovary, placenta and extraglandular tissues such as adipose tissue, skin and the brain. Aromatase activity is not detectable in normal endometrium. In contrast, aromatase is expressed aberrantly in endometriosis and is stimulated by prostaglandin E(2) (PGE(2)).( )This results in local production of estrogen, which induces PGE(2) formation and establishes a positive feedback cycle. Another abnormality in endometriosis, i.e. deficient hydroxysteroid dehydrogenase (17beta-HSD) type 2 expression, impairs the inactivation of estradiol to estrone. These molecular aberrations collectively favor accumulation of increasing quantities of estradiol and PGE(2 )in endometriosis. The clinical relevance of these findings was exemplified by the successful treatment of an unusually aggressive case of postmenopausal endometriosis using an aromatase inhibitor.

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