Analysis of Corticosterone and Testosterone Synthesis in Rat Salivary Gland Homogenates

Metabolomics Profiling of Stages of Coronary Artery Disease Progression

Coronary artery disease (CAD) and atherosclerosis pose significant global health challenges, with intricate molecular changes influencing disease progression. Hypercholesterolemia (HC), hypertension (HT), and diabetes are key contributors to CAD development. Metabolomics, with its comprehensive analysis of metabolites, offers a unique perspective on cardiovascular diseases. This study leveraged metabolomics profiling to investigate the progression of CAD, focusing on the interplay of hypercholesterolemia, hypertension, and diabetes. We performed a metabolomic analysis on 221 participants from four different groups: (I) healthy individuals, (II) individuals with hypercholesterolemia (HC), (III) individuals with both HC and hypertension (HT) or diabetes, and (IV) patients with self-reported coronary artery disease (CAD). Utilizing data from the Qatar Biobank, we combined clinical information, metabolomic profiling, and statistical analyses to identify key metabolites associated with CAD risk. Our data identified distinct metabolite profiles across the study groups, indicating changes in carbohydrate and lipid metabolism linked to CAD risk. Specifically, levels of mannitol/sorbitol, mannose, glucose, and ribitol increased, while pregnenediol sulfate, oleoylcarnitine, and quinolinate decreased with higher CAD risk. These findings suggest a significant role of sugar, steroid, and fatty acid metabolism in CAD progression and point to the need for further research on the correlation between quinolinate levels and CAD risk, potentially guiding targeted treatments for atherosclerosis. This study provides novel insights into the metabolomic changes associated with CAD progression, emphasizing the potential of metabolites as predictive biomarkers.

Impact of chronic psychological stress on platelet membrane fatty acid composition in a rat model of type 1 diabetes Mellitus

BACKGROUND

Chronic stress and diabetes mellitus are highly associated with oxidative stress and inflammation, resulting in cell membrane disruption and platelet activity. This study aims to evaluate the impact of chronic psychological stress on the composition of the platelet phospholipid membrane and platelet activation in type 1 diabetes mellitus (T1DM).

METHODS

We enrolled 35 mature healthy female Wistar rats and randomly divided them into 4 groups, namely the control group (n = 9), stress group (n = 10), T1DM group (n = 8), and T1DM + Stress group (n = 8). The Wistar rats were treated in different experimental conditions for 28 days while being provided free access to feed and water. The concentration of corticosterone in blood serum and hair samples was measured using a competitive enzyme-linked immunosorbent assay. Gas chromatography-mass spectrometry was conducted to identify the methyl esters of fatty acids (FAs) in the platelet phospholipid membrane. A quantitative determination of 11-dehydro-thromboxane B2 in the blood serum was also performed using a competitive enzyme-linked immunosorbent assay.

RESULTS

After 28 days, the concentration of corticosterone in blood serum (ng/mL) was observed to be higher in the stress group as compared to the T1DM and T1DM + Stress groups (P = 0.031 and P = 0.008, respectively). The percentage of C 16:0 FA in the platelet membrane was greater in the T1DM + Stress group, but its levels of C 20:1 omega (ω) 9 FA, including C 18:3ω3 FA, C 20:5ω3 FA, and the total sum of ω3 FAs, were lower as compared to the control group (P = 0.016; P = 0.016; P = 0.031; P = 0.016, P = 0.031). The concentration of 11-dehydro-thromboxane B2 in blood serum (pg/mL) was observed to be higher in the stress group than in rats with T1DM (P = 0.063).

CONCLUSION

Chronic psychological stress is related to higher levels of corticosterone, saturated FAs acids in the platelet membrane, and greater platelet activation. This study proves how a low percentage of unsaturated fatty acids in the DM and stress groups indicates the disturbing impact of the oxidative/inflammatory environment to lipid metabolism and neuroendocrine response.

Effect of Bee Bread on Corticosterone Level in Rat Dams Exposed to Gestational Heat Stress

Environmental temperature rises are powerful stimuli that can alter both the sympathetic nervous system and the hypothalamic-pituitary-adrenocortical axis (HPA). Heat stress has been shown to harm pregnancy outcomes such as causing spontaneous abortion, low birth weight, growth retardation and stillbirth. Supplementation of bee bread in pregnant rats under heat stress exposure has been shown to improve the pregnancy outcomes. However, whether supplementation of bee bread during heat stress exposure may also reduce the level of the stress hormone, corticosterone has yet been reported. Therefore, this study aims to determine the effect of bee bread on corticosterone level, progesterone level, oestradiol level and zonation of the adrenal cortex of pregnant rats under heat stress exposure. Pregnant rats were randomly categorised into four groups (n = 6): Control (C: standard feeding), Treatment 1 (T1: 0.5 g bee bread/kg body weight/day), Treatment 2 (T2: standard feeding with heat exposure), and Treatment 3 (T3: 0.5 g bee bread/kg body weight/day with heat exposure). Bee bread (0.5 g/kg body weight/day) was force-fed to pregnant rats through oral gavage beginning on day 0 of pregnancy and continuing until delivery. Heat stress was generated experimentally by putting both T2 and T3 rats in an egg incubator for 45 min daily at a temperature of 43°C till delivery. On a postnatal Day 21, dams were euthanised to assess serum corticosterone, progesterone, oestradiol levels and adrenal gland histology. Rats in the T2 group had a significantly (P < 0.05) increase in the zona fasciculata thickness (94.95 ± 1.55 μm) and higher corticosterone levels (49.57 ± 1.57 ng/mL) compared with control. However, supplementation of bee bread during heat stress was able to show an improvement in adrenal zona fasciculata thickness by decreasing to 79.89 ± 3.08 μm and corticosterone level reduced to 35.31 ± 1.73 ng/mL significantly (P < 0.05). Therefore, these findings may imply that bee bread is effective as a neutralizer in lowering the production of stress hormone.

Temperature and humidity index (THI) affects salivary cortisol (HC) and dehydroepiandrosterone (DHEA) concentrations in growing bulls following stress generated by performance test procedures

The hypothalamus-pituitary-adrenal axis response to a challenge was proposed for genetic selection of robust and resilient animals. As ACTH (adrenocorticotropic hormone) test and hormone measurements in blood may result impractical, it may be useful to measure salivary hormones in response to natural stressors, after an accurate biological validation, to control factors that could contribute to the response. We evaluated whether animal handling during performance test affects salivary HC and DHEA secretion and could be used for selection. We tested the effects of habituation to repeated handling and THI as putative bias. Bull calves (N = 273) undergoing performance test were sampled at 8-9 and 11-13 months (N = 101), 8-9 months (N = 131), or 11-13 months (N = 41). On each test day (D0), calves were isolated, conducted to a squeeze chute and immobilized for 6 min. Saliva samples were collected in the morning after feed administration (T0), and after 6 min immobilization in the squeeze chute (T1) for HC and DHEA measurement. Environmental temperature and relative humidity were recorded every hour from 1:00 h to 24:00 h during the 6 days before the performance test and on D0. Salivary HC and DHEA concentrations were higher in T1 (p < 0.01), although a clear individual positive response to handling could be observed in less than 10% of subjects. The mixed model revealed: (i) HC and HC/DHEA were higher in Young bulls (p < 0.05). (ii) The time of T0 sample collection significantly affected DHEA (p < 0.01) and HC/DHEA (p < 0.05). (iii) THI affected both steroids (p < 0.001) but not HC/DHEA. Spearman correlations suggested that THI weakly affected salivary HC at T0 only (ρ = 0.150, p < 0.01), while moderate statistically significant correlations were found between DHEA and THI at T0 (ρ = 0.316, p < 0.001), and T1 (ρ = 0.353, p < 0.001). Salivary HC and DHEA in response to handling procedures might identify subpopulations of subjects with sensitive HPA axis. Habituation to repeated handling played a role, as the hormone response was lower in older animals. Chronic exposure to high THI had a minor effect on salivary HC visible at T0. A more intense THI effect was observed on salivary DHEA concentrations at both T0 and T1, which should be worth of further investigations.

Analysis of salivary flow rate, biochemical composition, and redox status in orchiectomized spontaneously hypertensive rats

OBJECTIVE

This study aimed to analyze the salivary flow rate, biochemical composition, and redox status in orchiectomized spontaneously hypertensive rats (SHR) compared to normotensive Wistar rats.

DESIGN

Thirty-two young adult male SHR and Wistar (3-months-old) rats were randomly distributed into four groups; either castrated bilaterally (ORX) or underwent fictitious surgery (SHAM) as Wistar-SHAM, Wistar-ORX, SHR-SHAM, and SHR-ORX. Two months beyond castration, pilocarpine-induced salivary secretion was collected from 5-month-old rats to analyze salivary flow rate, pH, buffer capacity, total protein, amylase, calcium, phosphate, sodium, potassium, chloride, thiobarbituric acid reactive substances (TBARs), carbonyl protein, nitrite, and total antioxidant capacity.

RESULTS

The salivary flow rate was higher in the Wistar-ORX compared to the Wistar-SHAM group, while remaining similar between the SHR-SHAM and SHR-ORX groups. ORX did not affect pH and salivary buffer capacity in both strains. However, salivary total protein and amylase were significantly reduced in the Wistar-ORX and SHR-ORX compared to the respective SHAM groups. In both ORX groups, salivary total antioxidant capacity and carbonylated protein were increased, while lipid oxidative damage (TBARs) and nitrite concentration were higher only in the Wistar-ORX than in the Wistar-SHAM group. In the Wistar-ORX and SHR-ORX, the salivary calcium, phosphate, and chloride were increased while no change was detected in the SHAM groups. Only salivary buffering capacity, calcium, and chloride in the SHR-ORX adjusted to values similar to Wistar-SHAM group.

CONCLUSION

Hypertensive phenotype mitigated the orchiectomy-induced salivary dysfunction, since the disturbances were restricted to alterations in the salivary biochemical composition and redox state.

Determination of diurnal rhythm of salivary corticosterone concentration in the domestic rabbit (Oryctolagus cuniculus f. domestica) using a non-invasive method

There are many advantages associated with the determination of the level of corticosterone in rabbits from saliva, since this is a non-invasive sample collection method that does not affect their welfare and provides a reliable reflection of the state of the animal at a given moment without the results being distorted as they may be, for example, when blood samples are taken. The aim of this study was to determine the diurnal rhythm in the concentration of corticosterone in the saliva of the domestic rabbit. Saliva samples were taken from six domestic rabbits five times during the daytime (at 6:00, 9:00, 12:00, 15:00 and 18:00) over the course of three consecutive days. The levels of corticosterone in the saliva of the individual rabbits displayed a diurnal rhythm during the course of the day, with a significant increase between 12:00 and 15:00 (p < 0.05). No statistically significant difference in the concentrations of corticosterone in the saliva of the individual rabbits was demonstrated. Although the basal value of corticosterone is not known in rabbits and is difficult to determine, the results of our study show the pattern of fluctuations in the concentration of corticosterone in the saliva of rabbits during the daytime.

Glucocorticoids coordinate the bladder peripheral clock and diurnal micturition pattern in mice

Peripheral clocks function to regulate each organ and are synchronized though various molecular and behavioral signals. However, signals that entrain the bladder clock remain elusive. Here, we show that glucocorticoids are a key cue for the bladder clock in vitro and in vivo. A pBmal1-dLuc human urothelial cell-line showed significant shifts in gene expression after cortisol treatment. In vivo, rhythmic bladder clock gene expression was unchanged by bilateral adrenalectomy but shifted 4 h forward by corticosterone administration at the inactive phase. Moreover, the bladder clock shifted 8-12 h in mice that underwent both bilateral adrenalectomy and corticosterone administration at the inactive phase. These mice showed decreases in the diurnal rhythm of volume voided per micturition, while maintaining diurnal activity rhythms. These results indicate that the diurnal rhythm of glucocorticoid signaling is a zeitgeber that overcomes other bladder clock entrainment factors and coordinates the diurnal rhythm of volume voided per micturition.

Progress in salivary glands: Endocrine glands with immune functions

The production and secretion of saliva is an essential function of the salivary glands. Saliva is a complicated liquid with different functions, including moistening, digestion, mineralization, lubrication, and mucosal protection. This review focuses on the mechanism and neural regulation of salivary secretion, and saliva is secreted in response to various stimuli, including odor, taste, vision, and mastication. The chemical and physical properties of saliva change dynamically during physiological and pathophysiological processes. Moreover, the central nervous system modulates salivary secretion and function via various neurotransmitters and neuroreceptors. Smell, vision, and taste have been investigated for the connection between salivation and brain function. The immune and endocrine functions of the salivary glands have been explored recently. Salivary glands play an essential role in innate and adaptive immunity and protection. Various immune cells such as B cells, T cells, macrophages, and dendritic cells, as well as immunoglobins like IgA and IgG have been found in salivary glands. Evidence supports the synthesis of corticosterone, testosterone, and melatonin in salivary glands. Saliva contains many potential biomarkers derived from epithelial cells, gingival crevicular fluid, and serum. High level of matrix metalloproteinases and cytokines are potential markers for oral carcinoma, infectious disease in the oral cavity, and systemic disease. Further research is required to monitor and predict potential salivary biomarkers for health and disease in clinical practice and precision medicine.

The neurobiology of pain and facial movements in rodents: Clinical applications and current research

One of the most controversial aspects of the use of animals in science is the production of pain. Pain is a central ethical concern. The activation of neural pathways involved in the pain response has physiological, endocrine, and behavioral consequences, that can affect both the health and welfare of the animals, as well as the validity of research. The strategy to prevent these consequences requires understanding of the nociception process, pain itself, and how assessment can be performed using validated, non-invasive methods. The study of facial expressions related to pain has undergone considerable study with the finding that certain movements of the facial muscles (called facial action units) are associated with the presence and intensity of pain. This review, focused on rodents, discusses the neurobiology of facial expressions, clinical applications, and current research designed to better understand pain and the nociceptive pathway as a strategy for implementing refinement in biomedical research.

Effects of 4-hexylresorcinol administration on the submandibular glands in a growing rat model

Background

4-Hexylresorcinol (4HR) is a food additive and class I histone deacetylase inhibitor. In this study, we examined the effects of 4HR administration on the submandibular gland in a growing rat model.

Methods

Four-week-old rats were used in this study. The experimental group (nine males and eight females) received 12.8 mg/kg of 4HR weekly for 12 weeks. Ten rats (five males and five females) were used as controls. The submandibular glands of rats were collected 12 weeks after the first administration of 4HR. The weight of the glands was measured. Histological analysis, immunoprecipitation-high-performance liquid chromatography (IP-HPLC), and western blotting were performed.

Results

The weights of the rat submandibular glands were higher in the experimental groups than in the control group, especially in male rats (P < 0.05). The vascular endothelial growth factor (VEGF) and testosterone in the submandibular glands were more highly expressed in 4HR-treated male rats than in untreated rats, as detected by both western blotting and immunohistochemistry. The IP-HPLC results demonstrated that the expression levels of Ki67, epidermal growth factor, and testosterone in the submandibular glands were higher in 4HR-treated male rats than in untreated rats.

Conclusions

This study demonstrated that the systemic administration of 4HR increased the weight of submandibular glands in male rats. In addition, the testosterone and VEGF expression levels in the submandibular glands increased owing to 4HR administration.

Local aldosterone synthesis in the large intestine of mouse: An ex vivo incubation study

Objective

To investigate the regulation of local aldosterone synthesis by physiological stimulants in the murine gut.

Methods

Male mice were fed for 14 days with normal, high (1.6%) or low (0.01%) sodium diets. Tissue liver receptor homolog-1 and aldosterone in the colon and caecum were detected using an enzyme-linked immunosorbent assay (ELISA). Released corticosterone and aldosterone in tissue incubation experiments after stimulation with angiotensin II (Ang II) and dibutyryl-cAMP (DBA; the second messenger of adrenocorticotropic hormone) were assayed using an ELISA. Tissue aldosterone synthase (CYP11B2) protein levels were measured using an ELISA and Western blots.

Results

In incubated colon tissues, aldosterone synthase levels were increased by a low-sodium diet; and by Ang II and DBA in the normal diet group. Release of aldosterone into the incubation buffer was increased from the colon by a low-sodium diet and decreased by a high-sodium diet in parallel with changes in aldosterone synthase levels. In mice fed a normal diet, colon incubation with both Ang II and DBA increased the release of aldosterone as well as its precursor corticosterone.

Conclusion

Local aldosterone synthesis in the large intestine is stimulated by a low-sodium diet, dibutyryl-cAMP and Ang II similar to the adrenal glands.

Free d-Amino Acids in Salivary Gland in Rat

Free d-amino acids, which are enantiomers of l-amino acids, are found in mammals, including humans, and play an important role in a range of physiological functions in the central nervous system and peripheral tissues. Several d-amino acids have been observed in saliva, but their origin and the enzymes involved in their metabolism and catabolism remain to be clarified. In the present study, large amounts of d-aspartic acid and small amounts of d-serine and d-alanine were detected in all three major salivary glands in rat. No other d-enantiomers were detected. Protein expression of d-amino acid oxidase and d-aspartate oxidase, the enzymes responsible for the oxidative deamination of neutral and dicarboxylic d-amino acids, respectively, were detected in all three types of salivary gland. Furthermore, protein expression of the d-serine metabolic enzyme, serine racemase, in parotid glands amounted to approximately 40% of that observed in the cerebral cortex. The N-methyl-d-aspartic acid subunit proteins NR1 and NR2D were detected in all three major salivary glands. The results of the present study suggest that d-amino acids play a physiological role in a range of endocrine and exocrine function in salivary glands.

Induction of Salivary Gland-Like Tissue by Induced Pluripotent Stem Cells In Vitro

BACKGROUND

To investigate the in vitro induction of salivary gland-like tissue by ips cells in an interferon regulatory factor 6 (IRF6) overexpression and parotid conditioned medium environment.

METHODS

Urine-derived ips cells were isolated, identified, transfected with IRF6 and cultured in parotid conditioned medium to induce ips cells into salivary gland differentiation, morphological changes of ips cells were observed, CCK-8 was used to determine the cell proliferation efficiency and transcriptome sequencing was used to detect the expression of genes related to parotid gland formation.

RESULTS

Immunofluorescence staining showed that the isolated ips cells were positive for NANOG, SSEA4 and OCT4 and had embryonic-like stem cell characteristics; CCK-8 showed that there was no statistical difference in the proliferation efficiency between the IRF6⁺ induced group and the simple induced group after induction of ips cells into salivary glands. The results of transcriptome sequencing showed that there were a total of 643 differentially expressed genes, including 365 up-regulated genes and 278 down-regulated genes in the IRF6⁺ induced group compared to the blank control group, and the salivary gland related genes HAPLN1, CCL2, MSX2, ANXA1, CYP11A1, HES1 and LUM were all highly expressed in the IRF6⁺ induced group.

CONCLUSION

IRF6 promotes salivary gland differentiation in urine-derived iPSCs, and its mechanism of promoting differentiation may be that IRF6 upregulates the expression of HAPLN1, CCL2, MSX2, ANXA1, CYP11A1, HES1 and LUM to promote epithelial differentiation.

Testicular induced corticosterone synthesis in male rats under fasting stress

Testicular steroidogenesis is depressed by adrenal-secreted corticosterone (CORT) under stress. However, the mechanisms are not well understood. This study investigated the details of testicular steroidogenesis depression during fasting. Blood levels of adrenocorticotropic hormone secreted from the pituitary glands increased, but blood CORT was not changed in rats that fasted for 96 h, in spite of the rats being severely stressed. CORT in fasting adult male rats increased more than three times in the testis, but reduced testicular testosterone (T) and blood T levels to 5% and 2% of the control, respectively, was observed. The contents of T precursor (except PGN) were drastically reduced in the fasted-rat testes. Testicular CORT levels were elevated, but the enzymatic activity of cytochrome P45011β, which produces CORT, remained unchanged. The enzymatic activities of 3β-hydroxysteroid dehydrogenase (3β-HSD), mediating the conversion of pregnenolone to progesterone, decreased in the fasted-rat testes. Thus, fasting suppressed testicular steroidogenesis by affecting the enzyme activity of 3β-HSD in the testes and drastically reduced T and increased CORT synthesis. It can be considered that T synthesis involved in cell proliferation is suppressed due to lack of energy during fasting. Conversely, 11β-hydroxylase enzyme activity was induced and CORT synthesis is increased to cope with the fasting stress. Hence, it can be concluded that CORT synthesis in the testes plays a role in the local defense response.

Sex-related response in mice after sub-acute intraperitoneal exposure to silver nanoparticles

Silver nanoparticles (AgNPs) are among the most commercialized nanomaterials in biomedicine due to their antimicrobial and anti-inflammatory properties. Nevertheless, possible health hazards of exposure to AgNPs are yet to be understood and therefore raise public concern in regards of their safety. In this study, sex-related differences, role of steroidal hormones and influence of two different surface stabilizing agents (polymer vs. protein) on distribution and adverse effects of AgNPs were investigated in vivo. Intact and gonadectomised male and female mice were treated with seven AgNPs doses administered intraperitoneally during 21 days. After treatment, steroid hormone levels in serum, accumulation of Ag levels and oxidative stress biomarkers in liver, kidneys, brain and lungs were determined. Sex-related differences were observed in almost all tissues. Concentration of Ag was significantly higher in the liver of females compared to males. No significant difference was found for AgNP accumulation in lungs between females and males, while the lungs of intact males showed significantly higher Ag accumulation compared to gonadectomised group. Effect of surface coating was also observed, as Ag accumulation was significantly higher in kidneys and liver of intact females, as well as in kidneys and brain of intact males treated with protein-coated AgNPs compared to polymeric AgNPs. Oxidative stress response to AgNPs was the most pronounced in kidneys where protein-coated AgNPs induced stronger effects compared to polymeric AgNPs. Interestingly, protein-coated AgNPs reduced generation of reactive oxygen species in brains of females and gonadectomised males. Although there were no significant differences in levels of hormones in the AgNP-exposed animals compared to controls, sex-related differences in oxidative stress parameters were observed in all organs. Results of this study highlight the importance of including the sex-related differences and effects of protein corona in biosafety evaluation of AgNPs exposure.

Testosterone Deficiency Is a Risk Factor for Severe COVID-19

Background

Male sex is related to increased COVID-19 severity and fatality although confirmed infections are similarly distributed between men and women. The aim of this retrospective analysis was to investigate the impact of sex hormones on disease progression and immune activation in men with COVID-19.

Patients and Methods

We studied for effects of sex hormones on disease severity and immune activation in 377 patients (230 men, 147 women) with PCR-confirmed SARS-CoV-2 infections hospitalized at the Innsbruck University Hospital between February and December 2020.

Results

Men had more severe COVID-19 with concomitant higher immune system activation upon hospital admission when compared to women. Men with a severe course of infection had lower serum total testosterone (tT) levels whereas luteinizing hormone (LH) and estradiol (E2) levels were within the normal range. tT deficiency was associated with elevated CRP (rs = - 0.567, p < 0.001), IL-6 levels (rs = - 0.563, p < 0.001), lower cholesterol levels (rs = 0.407, p < 0.001) and an increased morbidity and mortality. Men with tT levels < 100 ng/dL had a more than eighteen-fold higher in-hospital mortality risk (OR 18.243 [95%CI 2.301 - 144.639], p = 0.006) compared to men with tT levels > 230 ng/dL. Moreover, while morbidity and mortality showed a positive correlation with E2 levels at admission, we detected a negative correlation with the tT/E2 ratio upon hospital admission.

Conclusion

Hospitalized men with COVID-19 present with rather low testosterone levels linked to more advanced immune activation, severe clinical manifestations translating into an increased risk for ICU admission or death. The underlying mechanisms remain elusive but may include infection driven hypogonadism as well as inflammation mediated cholesterol reduction causing gonadotropin suppression and impaired androgen formation. Finally, in elderly late onset hypogonadism might also contribute to lower testosterone levels.

Local biosynthesis of corticosterone in rat skeletal muscle

Adrenal corticosterone plays crucial roles in energy metabolism and immuno-reactivity throughout the body. As we have previously shown that corticosterone biosynthesis in C2C12 myoblasts, we study about corticosterone biosynthesis in rat skeletal muscles. It was found that enzymatic activities producing corticosterone and testosterone except the activity of P450scc in rat skeletal muscle as like as C2C12 cells. The CYP11B mRNA encoding cytochrome P45011β that mediates 11-deoxycorticosterone hydroxylase activity, producing corticosterone was expressed in skeletal muscles. In immunoblotting analysis, cytochrome P45011β protein was expressed in rat muscles and whole organs especially higher levels in adrenal and brain. The localizations of corticosterone content and enzymatic activities involved in the production of corticosterone were preferentially observed in gastrocnemius fibers rather than in soleus fibers. The immunohistochemical analysis showed that the fast-twitch or type II muscle fibers positive to antibody against fast myosin heavy chain were preferentially stained with anti-cytochrome P45011β antibody in the gastrocnemius fiber. In addition, we detected corticosterone biosynthesis from pregnenolone sulfate conjugates in perfusion of the rat hindquarter. Corticosterone is synthesized in rat skeletal muscles and the biosynthesis was localized in the fast-twitch or type II muscle fibers. We speculated that the local synthesized corticosterone might be involved in glucocorticoid-induced muscle atrophy that preferentially occurs in fast muscle fibers, and the initial substrate of the local CORT biosynthesis were supported to be performed from the conjugates such as pregnenolone sulfate circulating in the blood flow.