Keywords aging - liver - hepatic structure - testosterone - androgenic anabolic steroids - review
Introduction
After the second and third decades of life, testosterone levels decline gradually with advancing age, without a clear inflection point or andropause.[1 ]
The age-related decline in testosterone levels has been associated with reductions in muscle mass, strength, physical function, and libido.[2 ]
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At this point, testosterone administration as a therapy has been largely used to improve muscle mass, physical function, mobility, and frailty.[1 ]
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However, for several reasons, older men can be at a higher risk of experiencing adverse events during testosterone therapy when compared with young men. The plasma clearance of testosterone is lower in men aged ≥59 years than in young men (aged 19–35 years),[11 ] resulting in higher testosterone levels in older men at any testosterone dose.
Some adverse events associated with testosterone administration are prostate-related effects, and cardiovascular-related events.[12 ]
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[14 ] Furthermore, testosterone induces dose-dependent negative effects on the structure and function of the liver across age.[15 ]
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The liver has its functions changed with advancing age, resulting in impaired regeneration and in a decrease in drug metabolism.[18 ]
[19 ] Thus, testosterone administration can induce pathological conditions across age.[15 ]
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Currently, the clinical literature uses systematic reviews and meta-analyses to identify possible methodological differences in the studies, in the quality of the surveyed studies on a given topic, and in the most suitable intervention for a specific treatment.[8 ] Therefore, the present study aimed to carry out a systematic review of the effects of testosterone administration on the hepatic structure of adult and aged animals.
Materials and Methods
The present systematic review was developed based on the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guideline,[20 ] which is currently used for clinical studies. Therefore, Krause Neto and Nucci adapted it for this research.
On February, 2017, we performed a systematic review search in the PubMed, Google Scholar, Science Direct, Scielo and Lilacs databases, using the following Medical Subject Headings (MeSH) and entry terms: Liver OR Livers OR Bile Ducts ; Intrahepatic OR Bile Duct ; Intrahepatic OR Duct ; Intrahepatic Bile OR Ducts ; Intrahepatic Bile OR Intrahepatic Bile Duct OR Intrahepatic Bile Ducts OR Hepatocytes OR Hepatocyte OR Hepatic Cells OR Cell ; Hepatic OR Cells ; Hepatic OR Hepatic Cell OR Hep G2 Cells OR Cell ; Hep G2 OR Cells ; Hep G2 OR Hep G2 Cell OR HepG2 Cells OR Cell ; HepG2 OR Cells ; HepG2 OR HepG2 Cell OR Hep G2 Cell Line OR Hepatoblastoma G2 Cell Line OR Cell Line ; Hep G2 OR Cell Line ; Hepatoblastoma G2 OR Kupffer Cells OR Cells ; Kupffer OR Hepatic Stellate Cells OR Cell ; Hepatic Stellate OR Cells ; Hepatic Stellate OR Hepatic Stellate Cell OR Stellate Cell ; Hepatic OR Stellate Cells ; Hepatic OR Ito Cells OR Cells ; Ito OR Drug-Induced Liver Injury ; Chronic OR Drug Induced Liver Injury ; Chronic OR Liver Injury ; Drug-Induced, Chronic OR Chronic Drug-Induced Liver Injury OR Chronic Drug Induced Liver Injury ; AND testosterone OR 17-beta-Hydroxy-4-Androsten-3-one OR 17 beta hydroxy 4 androsten 3 one OR androtropy OR dr. kade brand of testosterone OR histone OR hauck brand of testosterone OR stereotaxy OR ulmer brand of testosterone OR sustain OR endoderm OR watson brand of testosterone OR faulding brand of testosterone OR paladin brand of testosterone OR astrazeneca brand of testosterone OR cepa brand of testosterone OR testoderm OR ortho brand of testosterone OR ferring brand of testosterone OR testolin OR pasadena brand of testosterone OR testopel OR barton brand of testosterone OR testosterone sulfate OR androgen OR solvay brand of testosterone OR univmed brand of testosterone OR schering brand of testosterone OR 8-Isotestosterone OR 8 isotestosterone OR 17-beta-Hydroxy-8 alpha-4-Androsten-3-one OR 17 beta hydroxy 8 alpha 4 androsten 3 one OR andropatch OR smithkline beecham brand of testosterone OR glaxosmithkline brand of testosterone OR testis OR auxilin pharmaceuticals inc. brand of testosterone OR testosterone propionate OR testosteronpropionat eifelfango OR propionate eifelfango, testosterone OR eifelfango brand of testosterone propionate OR virormone OR ferring brand of testosterone propionate OR agovirin OR testosterone 17 beta-cypionate OR testosterone 17 beta-cyclopentylpropionate OR testosterone cypionate OR testosterone 17 beta cyclopentanepropionate OR depo-testosterone OR pfizer brand of testosterone 17 beta-cypionate OR depo-testosterone cypionate OR leposternon OR duarte s OR roberts brand of testosterone 17 beta cypionate OR testa-c OR vojtech brand of testosterone 17 beta-cypionate OR tested elmu OR byk brand of testosterone 17 beta-cypionate OR andronati OR pasadena brand of testosterone 17 beta-cypionate OR depostomead OR spencer mead brand of testosterone 17 beta-cypionate OR testosterone enanthate OR testosterone heptylate OR testosterone heptanoate OR delatestryl OR theramex brand of testosterone enanthate OR btg brand of testosterone enanthate OR duraphat OR roberts brand of testosterone enanthate OR theramex OR testosterone depot rotexmedica OR rotexmedica brand of testosterone enanthate OR testosterone depot eifelfango OR eifelfango brand of testosterone enanthate OR testosterone depot jenapharm OR jenapharm brand of testosterone enanthate OR westrin p.a. OR pasadena brand of testosterone enanthate OR and repository OR rugby brand of testosterone enanthate OR primoteston depot OR schering brand of testosterone enanthate OR testosterone-17-succinate OR testosterone hydrogen succinate OR testosterone-17hemisuccinate OR T-17-HS OR testosterone hemisuccinate OR testosterone-17-succinate, sodium salt, (17beta) isomer OR testosterone-17-sulfate OR testosterone 17-sulphate OR testosterone-17-sulfate, sodium salt OR testosterone-17-sulfate, ammonium salt OR testosterone-17-sulfate, (17alpha) isomer OR testosterone undecanoate OR testosterone undecylate OR nebido OR understory OR andriole OR batstone OR restandol OR organon brand of testosterone undecanoate OR methyltestosterone OR 17 beta-Hydroxy-17-methyl-4-androsten-3-one OR 17 beta hydroxy 17 methyl 4 androsten 3 one OR 17beta methyltestosterone OR 17beta methyltestosterone OR 17-Epimethyltestosterone OR 17 epimethyltestosterone OR 17beta-Hydroxy-17-methyl-4-androsten-3-one OR 17beta hydroxy 17 methyl 4 androsten 3 one OR 17 beta methyltestosterone OR 17 beta-methyltestosterone OR android OR in band 1 of methyltestosterone OR Android-10 OR android 10 OR Android-25 OR android 25 OR Android-5 OR android 5 OR western OR mesterolone OR math test OR global pharmaceutical brand of methyltestosterone OR oregon OR schering brand of methyltestosterone OR testoviron OR tested OR in band 2 of methyltestosterone OR virion OR star brand of methyltestosterone OR 17alpha-Methyltestosterone OR 17 alpha OR methyltestosterone OR 17alpha-Methyltestosterone OR 17alpha methyltestosterone OR 17alpha-MethylTestosterone OR 17alpha methyl testosterone OR perandren OR testosterone 17-phenylpropionate OR testosterone phenylpropionate OR restandol OR testosterone decanoate OR testosterone replacement OR androgenic anabolic steroids OR anabolic steroids AND Aging OR Senescence OR Biological Aging OR Aging, Biological OR aged OR elderly OR Frail Elderly OR Elderly, Frail OR Frail Elders OR Elder, Frail OR Elders, Frail OR Frail Elder OR Functionally-Impaired Elderly OR Elderly, Functionally-Impaired OR Functionally Impaired Elderly OR Frail Older Adults OR Adult, Frail Older OR Adults, Frail Older OR Frail Older Adult OR Older Adult, Frail OR Older Adults, Frail .
Inclusion and Exclusion Criteria
We have searched for animal experimental design studies on the administration of testosterone on the hepatic structure and the effect of aging on it. The inclusion criteria were articles with healthy young, adult or aged rodents, testosterone administration, and detailed data on hepatic morphology. We have excluded all of the papers that investigated testosterone administration on genetically modified animals, interventions such as surgery, or the use of any drug or nutritional supplement combined with testosterone administration. The strain of the rodents was not stated as an inclusion criterion.
Outcomes
The outcomes of interest were the area and the number of nuclei of hepatocytes, which indicate mitosis related to hepatic injury, as well as lobular (capillaries sinusoids, perisinusoidal spaces, and biliary ducts) and non-lobular (portal spaces, veins, and center-lobular branches of blood vessels) parenchyma components, which indicate changes in the hepatic blood flow.
Data Extraction and Analysis of Data Quality
We have extracted data about the strain of the rodents, as well as their age, gender, testosterone administration dosage and duration, and primary outcomes. Usually, clinical systematic review researchers apply a data quality analysis on the methodology of the analyzed papers through specific topic questionnaires. However, questionnaires for these purposes do not exist for animal studies. Therefore, we did not apply any data quality analysis in the present study. Data such as strain and/or age of the rodents were not used in the search strategy so as to not limit the amount of included studies.
Data Synthesis and Analysis
The systematic review data was organized in [Tables 1 ] and [2 ].[15 ]
[16 ] For the meta-analysis, RevMan 5.2 software (The Nordic Cochrane Centre, Copenhagen, Denmark) was used to calculate heterogeneity by the i-squared (I2 ) and chi-squared (χ2 ) values. We have used the I2 to assess the heterogeneity/homogeneity between the studies, using fixed effect models. We have also used the inverse variance method and 95% total confidence interval (95%CI).
Table 1
Data description regarding the strain of the rodents, as well as their age, gender, testosterone dosage, frequency (times/week) and duration
Reference
Animal
strain
Age (months)
Gender
Testosterone
Before
After
Dosage
Frequency
(times/week)
Duration
(months)
Tanasov et al, 2014[16 ]
Wistar
13
16
Male
3 mg/kg
3
3
Nucci et al, 2017[15 ]
Wistar
20
24
Male
10 mg/kg
2
4
Table 2
Summary of primary outcomes regarding the area and the number of nuclei of hepatocytes, and of lobular and non-lobular parenchyma components in the groups that received testosterone
Reference
Hepacotyces nuclei
Parenchyma components
Number
Area
Lobular
Non-lobular
Tanasov et al, 2014[16 ]
Increased
Decreased
Increased
Decreased
Nucci et al, 2017[15 ]
Increased
Decreased
Increased
Decreased
The present study is an analysis of published data; thus, it did not require the approval of an ethics committee.
Results
Selected Studies
After the initial intersection of mesh terms, entry terms, and/or related keywords, the search identified 12,924 article titles. From this point, 4 evaluators (Nucci, Tanasov, de Souza and Gama) read the titles. Then, the abstracts were selected following the PRISMA[20 ] guideline. Of the total 12,924 articles, 52 were used for the initial abstract analysis. The abstracts should contain sufficient data on the parameters of the hepatic structure, on the animals studied, and on the treatments and/or interventions used in the studies. From these, five articles were included for full text analysis. After the inclusion and exclusion criteria were applied, two papers were included in the systematic review and meta-analysis.[15 ]
[16 ] However, the small number of included papers should be considered a limitation.
Animal Strain, Age and Gender
In the selected articles, the strain of rodents used was Wistar rats (Rattus norvegicus ). This strain is widely used in aging studies. Both studies presented data about the effects of testosterone administration on the hepatic structure of adult or aged animals. Both studies used male animals.
Testosterone Administration, Duration and Dosage
Tanasov et al[16 ] used testosterone propionate via intramuscular administration (3 mg/kg) for 3 months. However, Nucci et al[15 ] used testosterone propionate via intraperitoneal administration (10 mg/kg) for 4 months.
Data Synthesis
Both studies[15 ]
[16 ] used morphometrical and stereological methods to analyze the area and the number of nuclei of hepatocytes, as well as the lobular and non-lobular parenchyma components.
All data are presented by the analysis of 2 studies, and 24 animals were included. Only adult and aged rodent data was considered. Age effect has not been evaluated at this point because the included articles did not present enough internal statistical data.
Meta-analysis
Number of Nuclei of Hepatocytes
The forest plot analysis demonstrated homogeneity (p = 0.97; I2 = 0%) between the studies, and the testosterone administration had a non-significant (p = 0.15) increase of 3.23 hepatocyte nuclei per field (95% CI: -1.15–7.61). [Fig. 1 ] presents the data and the forest plot.
Fig. 1 Forest plot presenting information about the effects of testosterone administration on the number of nuclei of hepatocytes in adult and aged rats (figure created using theRevMan 5.2 2017)
Area of Nuclei of Hepatocytes
The forest plot analysis demonstrated homogeneity (p = 0.56; I2 = 0%) between the studies, and the testosterone administration had a non-significant (p = 0.52) decrease of 2.44 μm2 in the hepatocyte nuclei area (95% CI: -9.90–5.01). [Fig. 2 ] presents the data and the forest plot.
Fig. 2 Forest plot presenting information about the effects of testosterone administration on the area of nuclei of hepatocytes in adult and aged rats (figure created using the RevMan 5.2 2017)
Lobular Parenchyma Components
The forest plot analysis demonstrated heterogeneity (p = 0.04; I2 = 77%) between the studies, and the testosterone administration had a significant (p = 0.0008) increase of 5.77% in the lobular parenchyma components (95% CI: 2.40–9.15). [Fig. 3 ] presents the data and the forest plot.
Fig. 3 Forest plot presenting information about the effects of testosterone administration on the lobular parenchyma components in adult and aged rats (figure created using the RevMan 5.2 2017)
Non-lobular Parenchyma Components
The forest plot analysis demonstrated homogeneity (p = 0.98; I2 = 0%) between the studies, and the testosterone administration had a non-significant (p = 0.69) decrease of 1.21% of in the non-lobular parenchyma components (95% CI: -7.12–4.69). [Fig. 4 ] presents the data and the forest plot.
Fig. 4 Forest plot presenting information about the effects of testosterone administration on the non-lobular parenchyma components in adult and aged rats (figure created using the RevMan 5.2 2017)
Discussion
Through a systematic review with meta-analysis, the present article analyzed the effects of testosterone administration on the hepatic structure of adult and aged animals. We have shown through a meta-analysis that testosterone may increase the mitotic capacity of the hepatocytes. The merging of both studies showed a decrease in the hepatocyte nuclei area, as well as an increase in the number of hepatocyte nuclei per field. This is consistent with studies that highlighted the role of testosterone as a contributing factor in mitosis due to its chemical and toxic aggression to the hepatic tissue.[15 ]
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However, our major finding was that testosterone changed the hepatic blood flow by increasing the lobular parenchyma components in both studies.[15 ]
[16 ] Testosterone, at physiological concentrations, can selectively suppress the entry of calcium ions (Ca2+ ) via L-type Ca2+ channels, which indicates its vasodilatory actions.[23 ] Nonetheless, with testosterone administration, its vasodilatory actions could be more negative to the hepatic tissue in a dose-dependent fashion.
As the hepatic sinusoids dilate to accommodate the backflow of blood, the liver becomes tensely swollen.[24 ] Hence, this process may lead to blood stasis in the non-lobular parenchyma, leading to a hypoxic state. At this moment, a pathological process named hepatic congestion is characterized.[15 ]
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In addition, Simonetto et al[26 ] demonstrated through an experimental study in murine that chronic hepatic congestion leads to sinusoidal thrombosis and strain, which in turn promote hepatic fibrosis in the long-term. Additionally, a previous autopsy study of livers from patients with congestive heart failure demonstrated sinusoidal thrombi in the proximity of areas with fibrosis, and suggested a causative role of intrahepatic thrombosis in the incidence of fibrosis.[27 ] Furthermore, Nucci et al[15 ] showed that testosterone can injure the liver tissue, resulting in a sharp increase in fibrosis, which indicates chronic hepatic congestion in the short-term.
Conclusion
We have shown through a systematic review with meta-analysis that testosterone may cause chronic hepatic congestion in the short-term. However, the present review analyzed a small number of studies, which was considered a limitation. At this point, we encourage the development of more studies to elucidate the cellular and molecular mechanisms involved in hepatic injuries, as well as the hepatic metabolism of exogenous testosterone across age.
