Flutamide, an androgen receptor antagonist, improves heatstroke outcomes in mice

"Unravelling the impacts of climatic heat events on cardiovascular health in animal models"

Climate change has led to an increase in high ambient temperatures, causing extreme heat events worldwide. According to the World Meteorological Organization (WMO), July 2023 marked a historic milestone as the Earth reached its hottest recorded temperature, precisely hitting the critical threshold of 1.5 °C set by the Paris Agreement. This distressing development led to a stark warning from the United Nations, signaling the dawn of what they call "an era of global boiling". The increasing global temperatures can result in high heat stress which leads to various physiological and biochemical alterations in the human body. Given that cardiovascular diseases (CVDs) are a leading cause of morbidity and mortality globally, heat events exacerbate this public health issue. While clinical and in-vitro studies have suggested a range of pathophysiological and biochemical mechanisms underlying the body's response to heat stress, the complex nature of organ-system level interactions makes precise investigation challenging. To address this knowledge gap effectively, the use of animal models exposed to acute or chronic heat stress can be invaluable. These models can closely replicate the multifaceted effects observed in humans during heat stress conditions. Despite extensive independent reviews, limited focus has been shed on the high heat-induced cardiovascular complications and their mechanisms, particularly utilizing animal models. Therefore, in this comprehensive review, we highlight the crucial biomarkers altered during heat stress, contributing significantly to various CVDs. We explore potential mechanisms underlying heat-induced cardiovascular dysfunction and damage, delving into various animal models. While traditional rodent models are commonly employed, we also examine less conventional models, including ruminants, broilers, canines, and primates. Furthermore, we delve into various potential therapeutic approaches and preventive measures. These insights hold significant promise for the development of more effective clinical interventions against the effects of heat stress on the human cardiovascular system.

Pharmacological Activation Of Aldehyde Dehydrogenase 2 Protects Against Heatstroke-Induced Acute Lung Injury by Modulating Oxidative Stress and Endothelial Dysfunction

Heatstroke (HS) can cause acute lung injury (ALI). Heat stress induces inflammation and apoptosis via reactive oxygen species (ROS) and endogenous reactive aldehydes. Endothelial dysfunction also plays a crucial role in HS-induced ALI. Aldehyde dehydrogenase 2 (ALDH2) is a mitochondrial enzyme that detoxifies aldehydes such as 4-hydroxy-2-nonenal (4-HNE) protein adducts. A single point mutation in ALDH2 at E487K (ALDH2*2) intrinsically lowers the activity of ALDH2. Alda-1, an ALDH2 activator, attenuates the formation of 4-HNE protein adducts and ROS in several disease models. We hypothesized that ALDH2 can protect against heat stress-induced vascular inflammation and the accumulation of ROS and toxic aldehydes. Homozygous ALDH2*2 knock-in (KI) mice on a C57BL/6J background and C57BL/6J mice were used for the animal experiments. Human umbilical vein endothelial cells (HUVECs) were used for the in vitro experiment. The mice were directly subjected to whole-body heating (WBH, 42°C) for 1 h at 80% relative humidity. Alda-1 (16 mg/kg) was administered intraperitoneally prior to WBH. The severity of ALI was assessed by analyzing the protein levels and cell counts in the bronchoalveolar lavage fluid, the wet/dry ratio and histology. ALDH2*2 KI mice were susceptible to HS-induced ALI in vivo. Silencing ALDH2 induced 4-HNE and ROS accumulation in HUVECs subjected to heat stress. Alda-1 attenuated the heat stress-induced activation of inflammatory pathways, senescence and apoptosis in HUVECs. The lung homogenates of mice pretreated with Alda-1 exhibited significantly elevated ALDH2 activity and decreased ROS accumulation after WBH. Alda-1 significantly decreased the WBH-induced accumulation of 4-HNE and p65 and p38 activation. Here, we demonstrated the crucial roles of ALDH2 in protecting against heat stress-induced ROS production and vascular inflammation and preserving the viability of ECs. The activation of ALDH2 by Alda-1 attenuates WBH-induced ALI in vivo.

Desert Related Death

Introduction: Desert death is defined as any death that occurs in the desert and could be attributed to a list of causes including environmental, animal related, undetermined, and other causes. Death in the desert seems to be obscure and little discussed in the field of forensic medicine, despite its importance, and there is only limited literature available on this broad topic. This narrative review aims to identify the most common causes of desert death and its medicolegal implications. Desert death causes: Environmental causes of death could be a result of temperature and lightening-related causes. Moreover, a variety of animals found in deserts are considered to be threatening and fatal, in addition to other and undetermined causes. Medicolegal implications of desert death: Likely to arise from the difficulties faced in finding the cause of death are the identification of the victim and the postmortem injuries that occur. Conclusion: Desert death is a broad topic with great medicolegal significance. More information and case reports need to be added in the literature. Guidelines for people about the danger of going to deserts in specific weather conditions should be implemented. Safety regulations must be taken into account at all times.

Effects of Androgen Receptor Inhibition on Kanamycin-Induced Hearing Loss in Rats

Megalin has been proposed as an endocytic receptor for aminoglycosides as well as estrogen and androgen. We aimed to investigate the otoprotective effects of antiandrogens (flutamide, FM) on kanamycin (KM)-induced hearing loss in rats. Rats were divided into four groups. The KM group was administered KM (20 mg/kg/day) for 5 days, while the FM group received FM (15 mg/kg/day) for 10 days. In the KM + FM group, KM and FM (15 mg/kg/day) were simultaneously injected for 5 days and then FM was injected for 5 days. Auditory brainstem responses were measured. Western blotting and/or quantitative reverse transcriptase-polymerase chain reaction were performed for megalin, cytochrome P450 1A1 (Cyp1a1), Cyp1b1, metallothionein 1A (MT1A), MT2A, tumor necrosis factor (TNF)-α, caspase 3, and cleaved caspase 3. The FM + KM group showed attenuated auditory thresholds when compared with the KM group at 4, 8, 16, and 32 kHz (all p < 0.05). The KM + FM group showed lower megalin and Cyp1b1 levels than the KM group (all p < 0.05). The KM + FM group revealed lower MT1A, TNFα, and caspase 3 protein levels, compared with those in the KM group (all p < 0.05). Androgen receptor inhibition protects against cochlear injuries in KM-induced hearing loss rats by attenuating megalin expression, revealing anti-inflammatory and anti-apoptotic effects.

Testosterone protects against the development of widespread muscle pain in mice

Chronic widespread pain conditions are more prevalent in women than men, suggesting a role for gonadal hormones in the observed differences. Previously, we showed that female mice, compared to male, develop widespread, more severe, and longer-duration hyperalgesia in a model of activity-induced muscle pain. We hypothesized testosterone protects males from developing the female pain phenotype. We tested whether orchiectomy of males before induction of an activity-induced pain model produced a female phenotype and whether testosterone administration produced a male phenotype in females. Orchiectomy produced longer-lasting, more widespread hyperalgesia, similar to females. Administration of testosterone to females or orchiectomized males produced unilateral, shorter-lasting hyperalgesia. Prior studies show that the serotonin transporter (SERT) is increased in the nucleus raphe magnus (NRM) in models of chronic pain, and that blockade of SERT in the NRM reduces hyperalgesia. We examined potential sex differences in the distribution of SERT across brain sites involved in nociceptive processing using immunohistochemistry. A sex difference in SERT was found in the NRM in the activity-induced pain model; females had greater SERT immunoreactivity than males. This suggests that testosterone protects against development of widespread, long-lasting muscle pain and that alterations in SERT may underlie the sex differences.

The influence of sex steroid hormones on the response to trauma and burn injury

Trauma and related sequelae result in disturbance of homeostatic mechanisms frequently leading to cellular dysfunction and ultimately organ and system failure. Regardless of the type and severity of injury, gender dimorphism in outcomes following trauma have been reported, with females having lower mortality than males, suggesting that sex steroid hormones (SSH) play an important role in the response of body systems to trauma. In addition, several clinical and experimental studies have demonstrated the effects of SSH on the clinical course and outcomes following injury. Animal studies have reported the ability of SSH to modulate immune, inflammatory, metabolic and organ responses following traumatic injury. This indicates that homeostatic mechanisms, via direct and indirect pathways, can be maintained by SSH at local and systemic levels and hence result in more favourable prognosis. Here, we discuss the role and mechanisms by which SSH modulates the response of the body to injury by maintaining various processes and organ functions. Such properties of sex hormones represent potential novel therapeutic strategies and further our understanding of current therapies used following injury such as oxandrolone in burn-injured patients.

Androgens Mediate Sex-Dependent Gonadotropin Expression During Late Prenatal Development in the Mouse

Central organization of the hypothalamic-pituitary-gonadal axis is initiated during fetal life. At this critical time, gonadal hormones mediate sex-specific development of the hypothalamic-pituitary axis, which then dictates reproductive physiology and behavior in adulthood. Although studies have investigated the effects of prenatal androgens on central factors influencing gonadotropin-releasing hormone (GnRH) release, the impact of fetal androgens on gonadotrope function has been overlooked. In the current study, we demonstrated that gonadotropin gene expression and protein production were robustly elevated in female mice compared with males during late fetal development and that this sex difference was dependent on fetal androgens. Treatment of dams from embryonic day (E)15.5 to E17.5 with testosterone, dihydrotestosterone (DHT), or the androgen antagonist flutamide eliminated the sex difference at E18.5. Specifically, flutamide relieved the suppression in male gene expression, elevating the level to that of females, whereas testosterone or DHT attenuated female gene expression to male levels. The gonadotrope population is equivalent in males and females, and gonadotropic cells in both sexes express androgen receptors, suggesting that androgen-dependent transcriptional regulation can occur in these cells in either sex. Studies using mouse models lacking GnRH signaling show that GnRH is necessary for enhanced gonadotropin expression in females and is therefore required to observe the sex difference. Collectively, these data suggest that circuits controlling GnRH input to the fetal pituitary are unrestrained in females yet robustly inhibited in males via circulating androgens and demonstrate plasticity in gonadotropin synthesis and secretion in both sexes depending on the androgen milieu during late prenatal development.

Hepatoprotective effect of casodex after trauma hemorrhage in a rodent model

Casodex (bicalutamide), an androgen receptor antagonist, is used for the treatment of prostate cancer. Recent evidences show that Akt signaling pathway exerts organ-protective effects after injury. The aim of this study was to investigate whether Akt plays any role in the casodex-mediated attenuation of hepatic injury after trauma-hemorrhagic shock. Male Sprague-Dawley rats underwent trauma hemorrhage (mean blood pressure kept at approximately 35-40 mm Hg for 90 min), followed by fluid resuscitation. During resuscitation, a single dose of casodex (5 mg/kg, intravenous) with and without a phosphatidylinositol 3-kinase inhibitor wortmannin (1 mg/kg, intravenous), wortmannin or vehicle was administered. Plasma aspartate aminotransferase and alanine aminotransferase levels and various hepatic parameters were measured at 24 h after resuscitation. One-way analysis of variance and the Tukey test were used for statistical analysis. These results showed that trauma hemorrhage increased hepatic myeloperoxidase activity, interleukin 6 and intercellular adhesion molecule 1 levels, and plasma aspartate aminotransferase and alanine aminotransferase concentrations. In the trauma hemorrhage rats treated with casodex, these parameters were significantly improved. Casodex treatment also increased hepatic phospho-Akt expression compared with vehicle-treated trauma hemorrhaged rats. Coadministration of wortmannin with casodex abolished the casodex-induced advantageous effects on the aforementioned parameters and hepatic injury. Our results suggest that the protective effect of casodex administration on attenuation of hepatic injury after trauma hemorrhage, which is, at least in part, through Akt-dependent pathway.

Testosterone Depletion Induces Demethylation of Murine Reelin Promoter CpG Dinucleotides: A Preliminary Study

Schizophrenia (SZ) is a debilitating mental disorder characterized by psychotic events, abnormal social behavior, false beliefs, and auditory hallucinations. Hypermethylation of the promoter region of reelin (RELN), a gene involved in regulation of neuronal positioning during telencephalic development, is strongly associated with low protein expression in several cortical structures and promoter hypermethylation in brain from postmortem SZ subjects. Recent experimental data suggests that testosterone is able to promote RELN demethylation, although no direct evidence of hormonal influence on reelin promoter methylation was obtained. We investigated if reduced levels of plasma testosterone in adult male mice lead to Reln promoter demethylation. Animals were administered with flutamide, an antiandrogenic compound, and reelin promoter methylation was assessed using methylationspecific PCR using bisulfite DNA from cerebellum. We found that flutamide was able to significantly lower plasma testosterone when compared to control mice, and treatment did not influence animal survival and body weight. We also show that low plasma testosterone was associated with demethylation of a cytosine residue located at -860 in reelin promoter region. These preliminary data suggest that androgenic hormones can influence cerebral reelin demethylation. To our knowledge, this is the first experimental approach directly linking testosterone depletion and RELN promoter methylation.

Human recombinant factor VIIa may improve heat intolerance in mice by attenuating hypothalamic neuronal apoptosis and damage

Intolerance to heat exposure is believed to be associated with hypothalamo-pituitary-adrenocortical (HPA) axis impairment [reflected by decreases in blood concentrations of both adrenocorticotrophic-hormone (ACTH) and corticosterone]. The purpose of this study was to determine the effect of human recombinant factor VIIa (rfVIIa) on heat intolerance, HPA axis impairment, and hypothalamic inflammation, ischemic and oxidative damage, and apoptosis in mice under heat stress. Immediately after heat stress (41.2 °C for 1 h), mice were treated with vehicle (1 mL/kg of body weight) or rfVIIa (65-270 µg/kg of body weight) and then returned to room temperature (26 °C). Mice still alive on day 4 of heat exposure were considered survivors. Cellular ischemia markers (e.g., glutamate, lactate-to-pyruvate ratio), oxidative damage markers (e.g., nitric oxide metabolite, hydroxyl radials), and pro-inflammatory cytokines (e.g., interleukin-6, interleukin-1β, tumor necrosis factor-α) in hypothalamus were determined. In addition, blood concentrations of both ACTH and corticosterone were measured. Hypothalamic cell damage was assessed by determing the neuronal damage scores, whereas the hypothalamic cell apoptosis was determined by assessing the numbers of cells stained with terminal deoxynucleotidyl transferase-mediated αUTP nick-end labeling, caspase-3-positive cells, and platelet endothelial cell adhesion molecula-1-positive cells in hypothalamus. Compared with vehicle-treated heated mice, rfVIIa-treated heated mice had significantly higher fractional survival (8/10 vs 1/10), lesser thermoregulatory deficit (34.1 vs 24.8 °C), lesser extents of ischemic, oxidative, and inflammatory markers in hypothalamus, lesser neuronal damage scores and apoptosis in hypothalamus, and lesser HPA axis impairment. Human recombinant factor VIIa appears to exert a protective effect against heatstroke by attenuating hypothalamic cell apoptosis (due to ischemic, inflammatory, and oxidative damage) in mice.

Proteomic analysis of hypothalamic injury in heatstroke rats

Ischemic and oxidative damage to the hypothalamus may be associated with decreased heat tolerance as well as heatstroke formation. The present study explores the hypothalamic proteome mechanisms associated with heatstroke-mediated hypothalamic ischemia, and oxidative damage. Heatstroke rats had hypotension, hypothalamic ischemia, and lethality. In addition, they had hyperthermia and hypothalamic blood-brain-barrier disruption, oxidative stress, activated inflammation, and neuronal apoptosis and degeneration. 2DE combined LC-MS/MS revealed that heatstroke-induced ischemic injury and apoptosis were associated with upregulation of L-lactate dehydrogenase but downregulation of both dihydropyriminase-related protein and 14-3-3 Zeta isoform protein. Heat-induced blood-brain-barrier disruption might be related to upregulation of glial fibrillary acidic protein. Oxidative stress caused by heatstroke might be related to upregulation of cytosolic dehydrogenase-1. Also, heat-induced overproduction of proinflammatory cytokines might be associated with downregulation of stathmin 1. Heat-induced hypothalamic ischemia, apoptosis, injury (or upregulation of L-lactate dehydrogenase), blood-brain-barrier disruption (or upregulation of glial fibrillary acidic protein), oxidative stress (or upregulation of cytosolic dehydrogenase-1), and activated inflammation (or downregulation of stathmin 1) were all significantly reversed by whole body cooling. Our data indicate that cooling therapy improves outcomes of heatstroke by modulating hypothalamic proteome mechanisms.

A comparative study of the conformational equilibria, vibrational, (1)H and (13)C NMR spectra of isobutyranilide and its derivative the anticancer drug flutamide

The molecular structure of isobutyranilide and flutamide were investigated by DFT-B3LYP/6-311G(**) and MP2/6-311G(**) calculations. Isobutyranilide was predicted to exist predominantly in a planar cis conformation, while flutamide in non-planar structures with the CF3 and the NO2 groups adopting an out of the phenyl-plane configuration. The vibrational frequencies of the low energy structures of the two molecules were computed at the DFT-B3LYP level of theory. From the calculated Gibb's free energies, isobutyranilide is estimated to have an equilibrium mixture of 91% cis and 9% trans structures, while flutamide is calculated to have a mixture of 65% cis-cis and 28% trans-cis structures at 298.15K. The analysis of the observed vibrational spectra supports the presence of isobutyranilide in only one conformation at room temperature. From a 1:1 acetonitrile solvent experiment flutamide is determined to exist in more than one conformation at ambient temperature. Complete vibrational assignments of the normal modes of isobutyranilide and flutamide were provided on the basis of combined normal coordinate calculations and experimental Infrared and Raman spectra. The (1)H and (13)C NMR spectra of isobutyranilide were measured and their chemical shifts were compared to the corresponding ones of flutamide.

Heatstroke model for desert dry-heat environment and observed organ damage

BACKGROUND

Heatstroke is one of the most common clinical emergencies. Heatstroke that occurred in a dry-heat environment such as desert is usually more seriously effective and often leads to death. However, the report of the pathophysiologic mechanisms about heatstroke in dry-heat environment of desert has not been seen.

OBJECTIVES

Our objectives are to establish a rat model of heatstroke of dry-heat environment of desert, to assess the different degrees of damage of organ, and to preliminarily discuss the mechanism of heatstroke in dry-heat environment of desert.

METHODS

The first step, we have established a rat heatstroke model of dry heat environment of desert. The second step, we have accessed changes in morphology and blood indicators of heatstroke rats in dry-heat environment of desert.

RESULTS

The heatstroke rats have expressed the changing characteristics of mean arterial pressure, core temperature, and heart rate. The organ damage changed from mild to serious level, specifically in the morphology and blood enzymology parameters such as alanine aminotransferase, aspartate aminotransferase, creatinine, urea, uric acid, creatine kinase-MB, creatine kinase, and blood gas parameters such as base excess extracellular fluid and bicarbonate ions (HCO3-).

CONCLUSIONS

We have successfully established the rat heatstroke model of dry-heat environment of desert. We have identified heatstroke rats that presented changing characteristics on physiological indicators and varying degrees of organ damage, which are aggravated by the evolution of heatstroke in dry-heat environment of desert. We have preliminarily discussed the mechanism of heatstroke in dry-heat environment of desert.

Gender differences in sepsis: cardiovascular and immunological aspects

During sepsis, a complex network of cytokine, immune, and endothelial cell interactions occur and disturbances in the microcirculation cause organ dysfunction or even failure leading to high mortality in those patients. In this respect, numerous experimental and clinical studies indicate sex-specific differences in infectious diseases and sepsis.

Female gender has been demonstrated to be protective under such conditions, whereas male gender may be deleterious due to a diminished cell-mediated immune response and cardiovascular functions. Male sex hormones, i.e., androgens, have been shown to be suppressive on cell-mediated immune responses. In contrast, female sex hormones exhibit protective effects which may contribute to the natural advantages of females under septic conditions. Thus, the hormonal status has to be considered when treating septic patients.

Therefore, potential therapies could be derived from this knowledge. In this respect, administration of female sex hormones (estrogens and their precursors) may exert beneficial effects. Alternatively, blockade of male sex hormone receptors could result in maintained immune responses under adverse circulatory conditions. Finally, administration of agents that influence enzymes synthesizing female sex hormones which attenuate the levels of pro-inflammatory agents might exert salutary effects in septic patients. Prospective patient studies are required for transferring those important experimental findings into the clinical arena.

Ischemic and oxidative damage to the hypothalamus may be responsible for heat stroke

The hypothalamus may be involved in regulating homeostasis, motivation, and emotional behavior by controlling autonomic and endocrine activity. The hypothalamus communicates input from the thalamus to the pituitary gland, reticular activating substance, limbic system, and neocortex. This allows the output of pituitary hormones to respond to changes in autonomic nervous system activity. Environmental heat stress increases cutaneous blood flow and metabolism, and progressively decreases splanchnic blood flow. Severe heat exposure also decreases mean arterial pressure (MAP), increases intracranial pressure (ICP), and decreases cerebral perfusion pressure (CPP = MAP - ICP), all of which lead to cerebral ischemia and hypoxia. Compared with normothermic controls, rodents with heatstroke have higher hypothalamic values of cellular ischemia (e.g., glutamate and lactate-to-pyruvate ratio) and damage (e.g., glycerol) markers, pro-oxidant enzymes (e.g., lipid peroxidation and glutathione oxidation), proinflammatory cytokines (e.g., interleukin-1β and tumor necrosis factor-α), inducible nitric oxide synthase-dependent nitric oxide, and an indicator for the accumulation of polymorphonuclear leukocytes (e.g., myeloperoxidase activity), as well as neuronal damage (e.g., apoptosis, necrosis, and autophagy) after heatstroke. Hypothalamic values of antioxidant defenses (e.g., glutathione peroxidase and glutathione reductase), however, are lower. The ischemic, hypoxic, and oxidative damage to the hypothalamus during heatstroke may cause multiple organ dysfunction or failure through hypothalamic-pituitary-adrenal axis mechanisms. Finding the link between the signaling and heatstroke-induced hypothalamic oxidative and ischemic damage might allow us to clinically attenuate heatstroke. In particular, free radical scavengers, heat shock protein-70 inducers, hypervolemic hemodilution, inducible nitric oxide synthase inhibitors, progenitor stem cells, flutamide, estrogen, interleukin-1 receptor antagonists, glucocorticoid, activated protein C, and baicalin mitigate preclinical heatstroke levels.