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- Takahashi, Kayo, et al.
(författare)
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Increase in hypothalamic aromatase in macaque monkeys treated with anabolic-androgenic steroids : PET study with [C-11]vorozole
- 2011
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Ingår i: NeuroReport. - 0959-4965 .- 1473-558X. ; 22:7, s. 326-330
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Tidskriftsartikel (refereegranskat)abstract
- In an earlier study in rodents, we showed that the aromatase that converts androgens to estrogens in the preoptic area and bed nucleus of stria terminalis was significantly increased in concentration after exposure to anabolic-androgenic steroids. To confirm whether this occurs in primates, we conducted a positron emission tomographic study using macaque monkeys. Male rhesus monkeys were treated with nandrolone decanoate for 3 weeks. To measure aromatase concentrations, we performed positron emission tomographic imaging using a C-11-labeled specific aromatase inhibitor, [C-11] vorozole. After treatment with nandrolone, significant increase in [C-11] vorozole binding was observed in the hypothalamus but not other areas including the amygdala, which is also aromatase enriched. These findings in monkeys are consistent with those we obtained earlier in rats. These findings strongly suggest that aromatase in the hypothalamus may play a crucial role in the emotional instability of anabolic-androgenic steroids abusers. NeuroReport 22:326-330 (C) 2011 Wolters Kluwer Health vertical bar Lippincott Williams & Wilkins.
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- Dubol, Manon, et al.
(författare)
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Acute nicotine exposure blocks aromatase in the limbic brain of healthy women : A [11C]cetrozole PET study
- 2023
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Ingår i: Comprehensive Psychiatry. - : Elsevier. - 0010-440X .- 1532-8384. ; 123
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Tidskriftsartikel (refereegranskat)abstract
- Background: Of interest to women's mental health, a wealth of studies suggests sex differences in nicotine addiction and treatment response, but their psychoneuroendocrine underpinnings remain largely unknown. A pathway involving sex steroids could indeed be involved in the behavioural effects of nicotine, as it was found to inhibit aromatase in vitro and in vivo in rodents and non-human primates, respectively. Aromatase regulates the synthesis of oestrogens and, of relevance to addiction, is highly expressed in the limbic brain.Methods: The present study sought to investigate in vivo aromatase availability in relation to exposure to nicotine in healthy women. Structural magnetic resonance imaging and two [11C]cetrozole positron emission tomography (PET) scans were performed to assess the availability of aromatase before and after administration of nicotine. Gonadal hormones and cotinine levels were measured. Given the region-specific expression of aromatase, a ROI -based approach was employed to assess changes in [11C]cetrozole non-displaceable binding potential.Results: The highest availability of aromatase was found in the right and left thalamus. Upon nicotine exposure, [11C]cetrozole binding in the thalamus was acutely decreased bilaterally (Cohen's d =-0.99). In line, cotinine levels were negatively associated with aromatase availability in the thalamus, although as non-significant trend.Conclusions: These findings indicate acute blocking of aromatase availability by nicotine in the thalamic area. This suggests a new putative mechanism mediating the effects of nicotine on human behaviour, particularly relevant to sex differences in nicotine addiction.
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- Hall, Håkan, et al.
(författare)
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Pharmacological characterization of 18F-labeled vorozole analogs
- 2012
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Ingår i: Journal of labelled compounds & radiopharmaceuticals. - : Wiley. - 0362-4803 .- 1099-1344. ; 55:14, s. 484-490
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Tidskriftsartikel (refereegranskat)abstract
- Two F-18-labeled analogs of vorozole ([F-18]FVOZ and [F-18]FVOO) have been developed as potential tools for the in vivo characterization of aromatase. The pharmacologicalproperties of these radioligands were evaluated using in vitro binding and in vivo distribution studies in the rat and primate. Saturation binding studies using rat ovary gave K-D and B-max values of 0.21 +/- 0.1 nM and 210 +/- 20 fmol/mg, respectively, for [F-18]FVOZ, and 7.6 +/- 1nMand 293 +/- 12fmol/mg, respectively, for [F-18]FVOO. Organ distribution studies in rats showed the highest accumulation in the adrenal glands, with standardized uptake values (SUVs) of 15 to 20, followed by ovaries and liver with SUVs of approximately 5. Ex vivo and in vitro autoradiography of the rat brain showed specific binding of both [F-18]FVOZ and [F-18]FVOO mainly in the amygdala. Positron emission tomography (PET) studies were performed in the Rhesus monkey, and these showed displaceable binding in the amygdala and the hypothalamus preoptic area. The PET images were also analyzed using masked volume-wise principal component analysis. These studies suggest that [F-18]FVOZ might be a suitable tracer for the study of aromatase in vitro and in vivo, and could be an alternative to [C-11]vorozole in human PET studies.
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- Hall, Håkan, 1963-, et al.
(författare)
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Pharmacological characterization of 18F-labeled vorozole analogues.
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Two 18F-labeled analogues of vorozole ([18F]FVOZ and [18F]FVOO) have been developed as potential tools for the in vivo characterization of aromatase. The purpose of the project was to evaluate the pharmacological properties of these radioligands using a combination of in vitro binding and in vivo distribution studies in the rat and primate. Saturation binding studies with the radioligands in homogenates of rat ovary gave KD and Bmax values of 0.21 ± 0.1 nM and 210 ± 20 fmol/mg, respectively, for [18F]FVOZ, and 7.6 ± 1 nM and 293 ± 12 fmol/mg, respectively, for [18F]FVOO. Organ distribution studies in rats showed the highest accumulation in the adrenal glands, with standardized uptake values (SUVs) of 15 to 20, followed by ovaries and liver with SUVs of approximately 5. The SUVs in the remaining organs were between 0.5 and 1.5. There was probably some defluorination of both radioligands, as the accumulation of radioactivity in bone increased with time. The regional distribution in the brain was studied using ex vivo and in vitro autoradiography. In the brain, specific binding of both [18F]FVOZ and [18F]FVOO were found mainly in the amygdala. PET studies were performed in the Rhesus monkey, and these showed displaceable binding in the amygdala and the preoptic area of the hypothalamus. These studies suggest that [18F]FVOZ might be to be a suitable tracer for the study of aromatase in vitro and in vivo, and could be an alternative to [11C]vorozole in human PET-studies.
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- Immenschuh, Jana, et al.
(författare)
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Multimodal neuroimaging reveals neural correlates of aromatase availability in the female brain
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Background: Estrogens extend their influence beyond reproduction, having been associated with neural plasticity and therefore the potential to shape the brain. It is unknown if the availability of aromatase, which is responsible for local estrogen synthesis in the brain, is associated with neural morphology. Here the correlation between in vivo brain availability of aromatase, grey and white matter structure, and peripheral levels of estradiol in healthy, young women was investigated.Methods: [11C]cetrozole positron emission tomography was performed together with structural and diffusion magnetic resonance imaging to assess the availability of aromatase, grey and white matter volumes, cortical surface architecture and white matter microstructure, respectively. Bioavailable gonadal hormone levels were measured. Results: Aromatase availability was notably high in the thalamus, hypothalamus, and amygdala, positively correlating with the grey matter volume of these regions. Cortical thickness and gyrification of the prefrontal cortex, as well as white matter properties of the fornix, were associated with aromatase availability. This suggests the impact of estrogens on the grey matter areas to which high aromatase-expressing regions are connected, and projecting white matter tracts, all part of the limbic brain that is often involved in mental disorders. Brain aromatase availability did not correlate with peripheral bioavailable hormone levels, pointing to a unique role of brain-derived estrogens. Conclusions: These findings provide the first evidence of brain morphological characteristics being associated with aromatase availability, shedding light on the impact of estrogens on brain structure.
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- Jonasson, My, et al.
(författare)
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Quantification of aromatase binding in the female human brain using [11 C]cetrozole positron emission tomography.
- 2020
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Ingår i: Journal of Neuroscience Research. - : Wiley. - 0360-4012 .- 1097-4547. ; 98:11, s. 2208-2218
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Tidskriftsartikel (refereegranskat)abstract
- Aromatase, the enzyme that in the brain converts testosterone and androstenedione to estradiol and estrone, respectively, is a putative key factor in psychoneuroendocrinology. In vivo assessment of aromatase was performed to evaluate tracer kinetic models and optimal scan duration, for quantitative analysis of the aromatase positron emission tomography (PET) ligand [11 C]cetrozole. Anatomical magnetic resonance and 90-min dynamic [11 C]cetrozole PET-CT scans were performed on healthy women. Volume of interest (VOI)-based analyses with a plasma-input function were performed using the single-tissue and two-tissue (2TCM) reversible compartment models and plasma-input Logan analysis. Additionally, the simplified reference tissue model (SRTM), Logan reference tissue model (LRTM), and standardized uptake volume ratio model, with cerebellum as reference region, were evaluated. Parametric images were generated and regionally averaged voxel values were compared with VOI-based analyses of the reference tissue models. The optimal reference model was used for evaluation of a decreased scan duration. Differences between the plasma-input- and reference tissue-based methods and comparisons between scan durations were assessed by linear regression. The [11 C]cetrozole time-activity curves were best described by the 2TCM. SRTM nondisplaceable binding potential (BPND ), with cerebellum as reference region, can be used to estimate [11 C]cetrozole binding and generated robust and quantitatively accurate results for a reduced scan duration of 60 min. Receptor parametric mapping, a basis function implementation of SRTM, as well as LRTM, produced quantitatively accurate parametric images, showing BPND at the voxel level. As PET tracer, [11 C]cetrozole can be employed for relatively short brain scans to measure aromatase binding using a reference tissue-based approach.
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