Testosterone depletion by castration may protect mice from heat-induced multiple organ damage and lethality

Reversal of cold intolerance by testosterone in orchiectomized mice after tibial nerve transection

Cold intolerance is a debilitating effect of nerve injury, has a strong impact on the life of patients and no advisable treatment exists against it. Testosterone influences pain pathways and has analgesic effects. A recent study showed testosterone as being an agonist of TRPM8, the predominant ion channel that contributes to cold hypersensitivity after injury. We investigated the effect of testosterone on cold sensitivity after nerve injury. Specifically, using the double plate test (DPT) (thermo-neutral-plate: 31 ºC and cold-plate: 18 ºC) we determined the thermal preference of mice at different points during the study design consisting of: orchiectomy, tibial nerve transection (TNT) (30 days after orchiectomy), 15-days-repeated subcutaneous injections of testosterone enanthate (250 or 500 µg/kg/day) or vehicle (started 12 h after TNT surgery). Different parameters such as time spent on cold plates, distance traveled, animal speed on the cold- and thermo-neutral-plates were determined in naïve, sham and neuropathic animals. Neither orchiectomy nor sham TNT surgery generate effects on cold intolerance and animal activity while TNT surgery decreased the time spent on the cold-plate and the distance traveled during DPT. Testosterone administration reversed the effect of nerve injury, decreasing the cold hypersensitivity and increasing activity of TNT mice. However, the effect of testosterone on cold avoidance reduced with time and at 14 days after TNT surgery, a higher dose was needed to reverse the effect generated by nerve injury. This indicates that although testosterone administration has a positive effect on cold intolerance, it might not be suitable for prolongated treatment.

The ultra-acute steroid response to traumatic injury: a cohort study

OBJECTIVE

Trauma-induced steroid changes have been studied post-hospital admission, resulting in a lack of understanding of the speed and extent of the immediate endocrine response to injury. The Golden Hour study was designed to capture the ultra-acute response to traumatic injury.

DESIGN

We conducted an observational cohort study including adult male trauma patients <60 years, with blood samples drawn ≤1 h of major trauma by pre-hospital emergency responders.

METHODS

We recruited 31 adult male trauma patients (mean age 28 [range 19-59] years) with a mean injury severity score (ISS) of 16 (IQR 10-21). The median time to first sample was 35 (range 14-56) min, with follow-up samples collected 4-12 and 48-72 h post-injury. Serum steroids in patients and age- and sex-matched healthy controls (HCs) (n = 34) were analysed by tandem mass spectrometry.

RESULTS

Within 1 h of injury, we observed an increase in glucocorticoid and adrenal androgen biosynthesis. Cortisol and 11-hydroxyandrostendione increased rapidly, whilst cortisone and 11-ketoandrostenedione decreased, reflective of increased cortisol and 11-oxygenated androgen precursor biosynthesis by 11β-hydroxylase and increased cortisol activation by 11β-hydroxysteroid dehydrogenase type 1. Active classic gonadal androgens testosterone and 5α-dihydrotestosterone decreased, whilst the active 11-oxygenated androgen 11-ketotestosterone maintained pre-injury levels.

CONCLUSIONS

Changes in steroid biosynthesis and metabolism occur within minutes of traumatic injury. Studies that address whether ultra-early changes in steroid metabolism are associated with patient outcomes are now required.

The impact of castration on physiological responses to exertional heat stroke in mice

INTRODUCTION

The capability of male mice to exercise in hot environments without succumbing to exertional heat stroke (EHS) is markedly blunted compared to females. Epidemiological evidence in humans and other mammals also suggests some degree of greater vulnerability to heat stroke in males compared to females. The origins of these differences are unknown, but testosterone has previously been shown to induce faster elevations in core temperature during acute, passive heat exposure. In this study, we tested the hypothesis that loss of testosterone and related sex hormones through castration would improve the performance and heat tolerance of male mice during EHS exposure.

METHODS

Twenty-four male mice were randomly divided into 3 groups, untreated EHS mice (SHAM-EHS), castrated EHS mice (CAS+EHS) and naïve exercise controls (NAIVE). Exercise performance and physiological responses in the heat were monitored during EHS and early recovery. Two weeks later, blood and tissues were collected and analyzed for biomarkers of cardiac damage and testosterone.

RESULTS

Core temperature in CAS+EHS rose faster to 39.5°C in the early stages of the EHS trial (P<0.0001). However, both EHS groups ran similar distances, exhibited similar peak core temperatures and achieved similar exercise times in the heat, prior to symptom limitation (unconsciousness). CAS+EHS mice had ~10.5% lower body mass at the time of EHS, but this provided no apparent advantage in performance. There was no evidence of myocardial damage in any group, and testosterone levels were undetectable in CAS+EHS after gonadectomy.

CONCLUSIONS

The results of these experiments exclude the hypothesis that reduced performance of male mice during EHS trials is due to the effects of male sex hormones or intact gonads. However, the results are consistent with a role of male sex hormones or intact gonads in suppressing the early and rapid rise in core temperature during the early stages of exercise in the heat.

Brain Testosterone-CYP1B1 (Cytochrome P450 1B1) Generated Metabolite 6β-Hydroxytestosterone Promotes Neurogenic Hypertension and Inflammation

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Previously, we showed that peripheral administration of 6β-hydroxytestosterone, a CYP1B1 (cytochrome P450 1B1)-generated metabolite of testosterone, promotes angiotensin II-induced hypertension in male mice. However, the site of action and the underlying mechanism by which 6β-hydroxytestosterone contributes to angiotensin II-induced hypertension is not known. Angiotensin II increases blood pressure by its central action, and CYP1B1 is expressed in the brain. This study was conducted to determine whether testosterone-CYP1B1 generated metabolite 6β-hydroxytestosterone locally in the brain promotes the effect of systemic angiotensin II to produce hypertension in male mice. Central CYP1B1 knockdown in wild-type (Cyp1b1^+/+) mice by intracerebroventricular-adenovirus-GFP (green fluorescence protein)-CYP1B1-short hairpin (sh)RNA attenuated, whereas reconstitution of CYP1B1 by adenovirus-GFP-CYP1B1-DNA in the paraventricular nucleus but not in subfornical organ in Cyp1b1^−/− mice restored angiotensin II-induced increase in systolic blood pressure measured by tail-cuff. Intracerebroventricular-testosterone in orchidectomized (Orchi)-Cyp1b1^+/+ but not in Orchi-Cyp1b1^−/−, and intracerebroventricular-6β-hydroxytestosterone in the Orchi-Cyp1b1^−/− mice restored the angiotensin II-induced: (1) increase in mean arterial pressure measured by radiotelemetry, and autonomic imbalance; (2) reactive oxygen species production in the subfornical organ and paraventricular nucleus; (3) activation of microglia and astrocyte, and neuroinflammation in the paraventricular nucleus. The effect of intracerebroventricular-6β-hydroxytestosterone to restore the angiotensin II-induced increase in mean arterial pressure and autonomic imbalance in Orchi-Cyp1b1^−/− mice was inhibited by intracerebroventricular-small interfering (si)RNA-androgen receptor (AR) and GPRC6A (G protein-coupled receptor C6A). These data suggest that testosterone-CYP1B1-generated metabolite 6β-hydroxytestosterone, most likely in the paraventricular nucleus via AR and GPRC6A, contributes to angiotensin II-induced hypertension and neuroinflammation in male mice.

In Experimental Dilated Cardiomyopathy Heart Failure and Survival Are Adversely Affected by a Lack of Sexual Interactions

Nearly one in three people in the U.S. will develop heart failure (HF), characterized by fluid retention (edema) in the lungs and elsewhere. This leads to difficult breathing, deterioration of physical capacity, restriction of normal activities and death. There is little data about the safety and effects of sexual interactions in patients with HF. We tested whether a lack of sexual interactions affected pathophysiological outcomes in a pre-clinical mouse model of dilated cardiomyopathy that recapitulates the progressive stages of human HF. Male mice were randomly given access to, or deprived from, sexual interactions with female mice, which were confirmed by videography and generation of offspring. Cohousing with access to sexual interactions markedly prolonged survival, while cohousing without access to sexual activity did not. Sexual interactions improved systolic function, reduced HF-associated edema, altered transcription of heart contractile protein genes and decreased plasma testosterone levels. To determine whether testosterone levels contributed to survival, testosterone levels were experimentally reduced. Reduction of testosterone levels significantly prolonged survival. Taken together, in mice with dilated cardiomyopathy, sexual activity altered cardiac contractile gene transcription, improved systolic function, reduced edema and prolonged survival which may be in part due to lower testosterone levels.

Dietary wild bitter gourd displays selective androgen receptor modulator like activity and improves the muscle decline of orchidectomized mice

Loss of skeletal muscle mass and strength is often associated with disability and poor quality of life. Selective Androgen Receptor Modulators (SARMs) are under development as potential treatment. This study aims at examining the potential of wild bitter gourd (BG) as a SARM and its effects on the muscle decline induced by orchiectomy. In the cell-based androgen receptor (AR) transactivation assay, the BGP extract showed weak agonistic and antagonistic activities, resembling those of some SARMs. Male C57BL/6J mice were sham-operated (Sham group) or castrated (Cast groups) and fed a modified AIN-93G high sucrose diet supplemented without (Cast group) or with 5% lyophilized BG powder (Cast + BGP) or with testosterone propionate (7 mg TP per kg diet, Cast + TP) for 23 weeks. In contrast to the Cast + TP group, the BGP supplementation did not affect the serum testosterone concentration, and prostate and seminal vesicle mass. Both TP and BGP supplementation increased the weight of androgen responsive muscles, bulbocavernosus (BC) and levator ani (LA) (p < 0.05). The grip strength and the performance on a rotarod of the Cast + BGP group were comparable to those of the Cast + TP group (p > 0.05). The number of succinate dehydrogenase (SDH)-positive fibers of the Cast + BGP group was not significantly different from that of the Sham and Cast + TP groups (p > 0.05). The BGP supplementation up-regulated the Pgc1α, Ucp2 or Ucp3 gene expressions in skeletal muscles of castrated mice (p < 0.05). BGP showed some characteristics of the SARM and might improve skeletal muscle function through the up-regulation of mitochondrial biogenic genes and oxidative capacity, and ameliorated the castration-induced decline of skeletal muscle function in mice.

Sex-Specific and Estrous Cycle-Dependent Antidepressant-Like Effects and Hippocampal Akt Signaling of Leptin

Sex differences in the incidence of depression and antidepressant treatment responses are well documented. Depression is twice as common in women as in men. Recent studies indicate that low levels of leptin, an adipocyte-derived hormone, are associated with increased symptoms of depression in women. Leptin has been shown to produce antidepressant-like effects in male rodents. In the present study, we examined sex differences and estrous cycle variations in antidepressant-like responses to leptin. Leptin administration significantly reduced immobility, a putative measure of behavioral despair, in the forced swim test in intact female mice in the proestrus phase but not in the diestrus phase of the estrous cycle. Moreover, leptin administration stimulated Akt phosphorylation in the hippocampus of female mice in proestrus but not in diestrus, in correlation with its differential behavioral effects in these two phases of the cycle. Leptin-induced behavioral responses and stimulation of hippocampal Akt phosphorylation in female mice were abolished by ovariectomy. By contrast, the antidepressant-like effect of leptin in male mice was not affected by gonadectomy (castration). Pretreatment with 17β-estradiol restored sensitivity to the effects of leptin on behavior and hippocampal Akt phosphorylation in ovariectomized female mice. These results suggest leptin regulates depression-like behavior and hippocampal Akt signaling in a sex-specific and estrous cycle-dependent manner.

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.

Patient-derived tissue slice grafts accurately depict response of high-risk primary prostate cancer to androgen deprivation therapy

Background

Effective eradication of high-risk primary prostate cancer (HRPCa) could significantly decrease mortality from prostate cancer. However, the discovery of curative therapies for HRPCa is hampered by the lack of authentic preclinical models.

Methods

We improved upon tumorgraft models that have been shown to predict drug response in other cancer types by implanting thin, precision-cut slices of HRPCa under the renal capsule of immunodeficient mice. Tissue slice grafts (TSGs) from 6 cases of HRPCa were established in mice. Following androgen deprivation by castration, TSGs were recovered and the presence and phenotype of cancer cells were evaluated.

Results

High-grade cancer in TSGs generated from HRPCa displayed characteristic Gleason patterns and biomarker expression. Response to androgen deprivation therapy (ADT) was as in humans, with some cases exhibiting complete pathologic regression and others showing resistance to castration. As in humans, ADT decreased cell proliferation and prostate-specific antigen expression in TSGs. Adverse pathological features of parent HRPCa were associated with lack of regression of cancer in corresponding TSGs after ADT. Castration-resistant cancer cells remaining in TSGs showed upregulated expression of androgen receptor target genes, as occurs in castration-resistant prostate cancer (CRPC) in humans. Finally, a rare subset of castration-resistant cancer cells in TSGs underwent epithelial-mesenchymal transition, a process also observed in CRPC in humans.

Conclusions

Our study demonstrates the feasibility of generating TSGs from multiple patients and of generating a relatively large number of TSGs from the same HRPCa specimen with similar cell composition and histology among control and experimental samples in an in vivo setting. The authentic response of TSGs to ADT, which has been extensively characterized in humans, suggests that TSGs can serve as a surrogate model for clinical trials to achieve rapid and less expensive screening of therapeutics for HRPCa and primary CRPC.

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

Flutamide has been used as an adjunct for decreasing the mortality from subsequent sepsis. Heatstroke resembles septic shock in many aspects. We hypothesized that heat-induced multiple organ dysfunction syndromes and lethality could be reduced by flutamide therapy. In heatstroke groups, mice were exposed to whole body heating (41.2°C, for 1h) in a controlled-environment chamber. The heat-stressed mice were returned to normal room temperature (24°C) after whole body heating. Mice still alive on day 4 of WBH treatment were considered survivors. Physiological and biochemical parameters were monitored for 2.5h post-WBH. Heatstroke mice were subcutaneously treated with flutamide (12.5-50mg/kg body weight in 0.05 ml) or vehicle solution (0.05 ml/kg body weight) once daily for 3 consecutive days post-WBH. We evaluated the effect of flutamide in heatstroke mice and showed that flutamide significantly (i) attenuated hypothermia, (ii) reduced the number of apoptotic cells in the hypothalamus, the spleen, the liver, and the kidney, (iii) attenuated the plasma index of toxic oxidizing radicals (e.g., nitric oxide metabolites and hydroxyl radicals), (iv) diminished the plasma index of the organ injury index (e.g., lactate dehydrogenase), (v) attenuated plasma systemic inflammation response molecules (e.g., tumor necrosis factor-α and interleukin-6), (vi) reduced the index of infiltration of polymorphonuclear neutrophils in the lung (e.g., myeloperoxidase activity), and (vii) allowed three times the fractional survival compared with vehicle. Thus, flutamide appears to be a novel agent for the treatment of mice with heatstroke or patients in the early stage of heatstroke.

Markers associated with testosterone enhancement of methamphetamine-induced striatal dopaminergic neurotoxicity

Intact male CD-1 mice received an injection of testosterone propionate (TP--5 ug), progesterone (P--5 mg), the oil vehicle or remained untreated (control). At 24 hours after hormonal treatments the mice received an injection of methamphetamine (MA--40 mg/kg) and rectal temperatures were measured. At 5 days post-MA, assays were performed to assess effects of these treatments. Maximal increases in body temperatures, that were significantly greater than oil-treated controls, were obtained in TP-treated mice. At 5 days post-MA, maximal weight reductions were obtained with TP-treated mice, while P-treated mice showed no significant decrease between the pre- versus post-MA determinations. Striatal dopamine concentrations showed maximal reductions and heat-shock protein-70 maximal increases in the TP group, with both differing significantly as compared with all other groups. Protein levels of dopamine transporters were significantly decreased in P-treated mice, while vesicular monoamine transporter-2 was significantly decreased in TP-treated mice. Taken together, these results suggest that testosterone exacerbates the deleterious effects of MA within male mice as indicated by a number of markers related to neurotoxicity. The changes in markers as associated with this enhanced neurotoxicity suggest that TP may increase thermal/energy responses and/or oxidative stress to produce this effect.

Perinatal dexamethasone-induced alterations in apoptosis within the hippocampus and paraventricular nucleus of the hypothalamus are influenced by age and sex

Exposure to high levels of glucocorticoids (GCs) during development leads to long-term changes in hypothalamic-pituitary-adrenal (HPA) axis regulation, although little is known about the neural mechanisms that underlie these alterations. In this study, we investigated the effects of late gestational (days 18-22) or postnatal (days 4-6) administration of the GC receptor agonist dexamethasone (DEX) on an apoptosis marker in two brain regions critical to HPA axis regulation, the hippocampus and the hypothalamic paraventricular nucleus (PVN). One day after the final DEX injection, male and female rats were sacrificed, and brains were processed for immunohistochemical detection of cleaved caspase-3, an apoptotic cell death indicator. DEX increased cleaved caspase-3 immunoreactivity in the CA1 hippocampal region of both sexes following prenatal but not postnatal treatment. Prenatal DEX also increased caspase-3 immunoreactivity in the CA3 region, an elevation that tended to be greater in females. In contrast, postnatal DEX resulted in a much smaller, albeit significant, induction in CA3 caspase-3 compared with prenatal treatment. Quantitative real-time PCR analysis revealed that prenatal but not postnatal DEX-induced hippocampal cleaved caspase-3 correlated with elevated mRNA of the proapoptotic gene Bad. Few caspase-3-ir cells were identified within the PVN regardless of treatment age, although postnatal but not prenatal DEX increased this number. However, the region immediately surrounding the PVN (peri-PVN) showed significant increases in caspase-3-ir cells following pre- and postnatal DEX. Together these findings indicate that developmental GC exposure increases apoptosis in HPAaxis-associated brain regions in an age- and sex-dependent manner.