Jesús M. Torres

Adiponectin activates AMP-activated protein kinase in muscle cells via APPL1/LKB1-dependent and phospholipase C/Ca2+/Ca2+/calmodulin-dependent protein kinase kinase-dependent pathways

The binding of the adaptor protein APPL1 to adiponectin receptors is necessary for adiponectin-induced AMP-activated protein kinase (AMPK) activation in muscle, yet the underlying molecular mechanism remains unknown. Here we show that in muscle cells adiponectin and metformin induce AMPK activation by promoting APPL1-dependent LKB1 cytosolic translocation. APPL1 mediates adiponectin signaling by directly interacting with adiponectin receptors and enhances LKB1 cytosolic localization by anchoring this kinase in the cytosol. Adiponectin also activates another AMPK upstream kinase Ca2+/calmodulin-dependent protein kinase kinase by activating phospholipase C and subsequently inducing Ca2+ release from the endoplasmic reticulum, which plays a minor role in AMPK activation. Our results show that in muscle cells adiponectin is able to activate AMPK via two distinct mechanisms as follows: a major pathway (the APPL1/LKB1-dependent pathway) that promotes the cytosolic localization of LKB1 and a minor pathway (the phospholipase C/Ca2+/Ca2+/calmodulin-dependent protein kinase kinase-dependent pathway) that stimulates Ca2+ release from intracellular stores.

Effects of acute alcohol intoxication on pituitary-gonadal axis hormones, pituitary-adrenal axis hormones, β-endorphin and prolactin in human adolescents of both sexes

Teenage drinking continues to be a major problem in industrialized countries, where almost 35% of alcohol drinkers are under 16 years old. In the present paper we studied the effects of acute alcohol intoxication (AAI) on the pituitary-gonadal (PG) axis hormones, and the possible contribution of pituitary-adrenal (PA) axis hormones, beta-endorphin (BEND), and prolactin (PRL) to the alcohol-induced dysfunction of PG axis hormones. Blood samples were drawn from adolescents that arrived at the emergency department with evident behavioral symptoms of drunkenness (AAI) or with nil consumption of alcohol (controls [C]). Our results demonstrated that AAI produces in adolescents a high increase in plasma PRL, ACTH, and cortisol (F), and a contradictory behavior of testosterone (T) according to gender: plasma T was increased in females and decreased in males. ACTH and PRL correlated positively with F, dehydroepiandrosterone-sulphate (DHEAS) and T in females, which suggests that PRL and ACTH could synergistically stimulate adrenal androgen production. In contrast, the decrease in T and increase in BEND in males suggests that AAI could have an inhibitory effect on testicular T, perhaps mediated by BEND. The hormones studied are involved in the development of secondary sexual characteristics and the growth axis during adolescence. The deleterious effects of alcohol abuse should be made known to adolescents and the appropriate authorities.

Alcohol intoxication increases allopregnanolone levels in male adolescent humans

RationaleTeenage drinking is a cause of growing concern in industrialized countries, where almost 35% of alcohol drinkers are under 16 years old. Increased anxiety, irritability and depression among adolescents may induce them to seek the anxiolytic and rewarding properties of alcohol. Allopregnanolone is rewarding in rodents, and therefore may contribute to the effects of alcohol.ObjectiveIn this paper, we studied the effects of acute alcohol intoxication on the plasma levels of allopregnanolone in male adolescents.MethodsBlood samples were drawn from male adolescents who arrived at the Emergency Department of the Hospital. Two groups were studied: one study group was formed by adolescents who arrived with evident behavioral symptoms of acute alcohol intoxication (AAI) and the other by those arriving for mild trauma (contusions, sprains) after no consumption of alcohol (Controls).ResultsOur results demonstrate that AAI significantly increases serum allopregnanolone levels in male adolescents.ConclusionsBecause alcohol and allopregnanolone positively modulate gamma-aminobutyric acid type A (GABAA) receptors, allopregnanolone may play a major role in the anxiolytic and rewarding effects of alcohol, either directly or by influencing the sensitivity of GABAA receptors to alcohol.

Bisphenol A Exposure during Adulthood Alters Expression of Aromatase and 5α-Reductase Isozymes in Rat Prostate

The high incidence of prostate cancer (PCa) and benign prostatic hypertrophy (BPH) in elderly men is a cause of increasing public health concern. In recent years, various environmental endocrine disruptors, such as bisphenol A (BPA), have been shown to disrupt sexual organs, including the prostate gland. However, the mechanisms underlying these effects remain unclear. Because androgens and estrogens are important factors in prostate physiopathology, our objective was to examine in rat ventral prostate the effects of adult exposure to BPA on 5α-Reductase isozymes (5α-R types 1, 2, and 3) and aromatase, key enzymes in the biosynthesis of dihydrotestosterone and estradiol, respectively. Adult rats were subcutaneously injected for four days with BPA (25, 50, 300, or 600 µg/Kg/d) dissolved in vehicle. Quantitative RT-PCR, western blot and immunohistochemical analyses showed lower mRNA and protein levels of 5α-R1 and 5α-R2 in BPA-treated groups versus controls but higher mRNA levels of 5α-R3, recently proposed as a biomarker of malignancy. However, BPA treatment augmented mRNA and protein levels of aromatase, whose increase has been described in prostate diseases. BPA-treated rats also evidenced a higher plasma estradiol/testosterone ratio, which is associated with prostate disease. Our results may offer new insights into the role of BPA in the development of prostate disease and may be of great value for studying the prostate disease risk associated with exposure to BPA in adulthood.

Effects of CRH and ACTH administration on plasma and brain neurosteroid levels.

The 3α-hydroxy ring A-reduced metabolite of progesterone, 3α-hydroxy-5α-pregnan-20-one (allopregnanolone) is among the most potent known ligands of the gamma aminobutyric acid (GABA) receptor, designated GABA-A, in the central nervous system. We determined by RIA serum levels of progesterone (PROG), 5-α-dihidroprogesterone (DHP) and allopregnanolone in male and female rats after corticotropin releasing hormone (CRH) and adrenocorticotropin hormone (ACTH) administration. Allopregnanolone was undetectable in plasma and brain of control males but detectable in plasma and brain of males injected with CRH and ACTH and of control and similarly treated females. Allopregnanolone increased in the plasma and brain after CRH and ACTH administration in all cases. The data demonstrate that the administration of CRH plus ACTH results in a rapid increase of the neuroactive steroid allopregnanolone in the brain of males and females to levels known to modulate GABA-A receptor function. Thus, stress could regulate neurosteroid biosynthesis via the hormones ACTH and CRH.

DHEA, PREG and their sulphate derivatives on plasma and brain after CRH and ACTH administration.

The term neurosteroids applies to steroids that are synthesized in the nervous system, either de novo from cholesterol or from steroid hormone precursors. RIA was used to determine plasma and brain levels of the neurosteroids pregnenolone (PREG), ehydroepiandrosterone (DHEA), and their sulfate derivatives (PREG-S and DHEA-S) in male and female rats after administration of two typical stress hormones: corticotropin-releasing hormone (CRH) and adrenocorticotropin hormone (ACTH). In all cases, the parameters measured were detectable in plasma and brain. PREG, PREG-S, and DHEA increased significantly in plasma and brain after CRH and ACTH administration in males and females. Because neurosteroids play an important role in mammalian physiology, including that of humans, stress situations may alter the physiological functions regulated by these neurosteroids.

Bisphenol A, bisphenol F and bisphenol S affect differently 5α-reductase expression and dopamine–serotonin systems in the prefrontal cortex of juvenile female rats

BACKGROUND Early-life exposure to the endocrine disruptor bisphenol A (BPA) affects brain function and behavior, which might be attributed to its interference with hormonal steroid signaling and/or neurotransmitter systems. Alternatively, the use of structural analogs of BPA, mainly bisphenol F (BPF) and bisphenol S (BPS), has increased recently. However, limited in vivo toxicity data exist. OBJECTIVES We investigated the effects of BPA, BPF and BPS on 5α-reductase (5α-R), a key enzyme involved in neurosteroidogenesis, as well as on dopamine (DA)- and serotonin (5-HT)-related genes, in the prefrontal cortex (PFC) of juvenile female rats. METHODS Gestating Wistar rats were treated with either vehicle or 10 μg/kg/day of BPA, BPF or BPS from gestational day 12 to parturition. Then, female pups were exposed from postnatal day 1 through day 21 (PND21), when they were euthanized and RT-PCR, western blot and quantitative PCR-array experiments were performed. RESULTS BPA decreased 5α-R2 and 5α-R3 mRNA and protein levels, while both BPF and BPS decreased 5α-R3 mRNA levels in PFC at PND21. Further, BPA, BPF and BPS significantly altered, respectively, the transcription of 25, 56 and 24 genes out of the 84 DA and 5-HT-related genes assayed. Of particular interest was the strong induction by all these bisphenols of Cyp2d4, implicated in corticosteroids synthesis. CONCLUSIONS Our results demonstrate for the first time that BPA, BPF and BPS differentially affect 5α-R and genes related to DA/5-HT systems in the female PFC. In vivo evidence of the potential adverse effects of BPF and BPS in the brain of mammals is provided in this work, raising questions about the safety of these chemicals as substitutes for BPA.

Effects of swim stress on mRNA and protein levels of steroid 5α-reductase isozymes in prefrontal cortex of adult male rats

The metabolite of progesterone, allopregnanolone, is among the most potent known ligands of the gamma-aminobutyric acid receptor complex (GABA(A)-R) in the central nervous system. This neuroactive steroid is markedly increased in an animal model of acute stress. Allopregnanolone is synthesized from progesterone by steroidogenic enzymes 5alpha-reductase (5alpha-R) and 3alpha-hydroxysteroid dehydrogenase (3alpha-HSD), with the former being the rate-limiting enzyme in this reaction sequence. In this paper, a quantitative RT-PCR method coupled to laser-induced fluorescence capillary electrophoresis (LIF-CE) and Western blot were used to measure both mRNA and protein levels of 5alpha-R type 1 (5alpha-R1) and 5alpha-R type 2 (5alpha-R2) isozymes in prefrontal cortex of male rats after acute swim stress situations. Our results demonstrate that both 5alpha-R isozymes are significantly higher in prefrontal cortex of male rats after acute swim stress in comparison with control rats. These data may open up a new research line that could improve our understanding of the role of 5alpha-R isozymes in processes that accompany stress situations.

Effects of Sulpiride on Prolactin and mRNA Levels of Steroid 5α-reductase Isozymes in Adult Rat Brain

Prolactin (PRL) promotes maternal behavior (MB), a complex pattern of behavior aimed at maximizing offspring survival. 3α,5α-reduced neurosteroids may also regulate MB. Indeed, PRL, 3α,5α-reduced neurosteroids, and 5α-reductase (5α-R), the key enzyme in the biosynthesis of these neuroactive steroids, are all increased in stress situations These facts led us to hypothesize a possible interrelation between PRL levels and 5α-R. In the present study we quantified mRNA levels of both 5α-R isozymes in prefrontal cortex of male and female rats after administration of sulpiride, an inductor of PRL secretion. Our results demonstrated that mRNA levels of both 5α-R isozymes were significantly increased in male and female rats by sulpiride, directly or via sulpiride-induced hyperprolactinemia. Since 3α,5α-reduced neurosteroids and PRL exert anxiolytic effects in response to stress, these molecules and 5α-R may possibly participate in a common pathway of significant adaptation to stress situations.

Semiquantitative RT-PCR method coupled to capillary electrophoresis to study 5alpha-reductase mRNA isozymes in rat ventral prostate in different androgen status.

The development and growth of the prostate gland depends on androgen stimulation. Dihydrotestosterone (DHT) is the primary androgen responsible for prostate development and also for the pathogenesis of benign prostatic hyperplasia (BPH). The incidence of prostate cancer (PCa) and benign prostatic hypertrophy (BPH) continues to rise in the Western world. DHT is synthesized in prostate from circulating testosterone (T) through the action of 5α-Reductase (5α-R) (EC 1.3.99.5), which occurs as two isozymes, type 1 and type 2. Type-1 5α-R is widely distributed in the body, and type-2 5α-R is confined to androgen-dependent structures. Both types are expressed in the prostate: type-2 isozyme is implicated in BPH and PCa; type-1 isozyme is also increased in some prostatic adenocarcinomas. In recent years, various inhibitors of type-2 isozyme or of both type-1 and type-2 isozyme have been used in prostatic diseases. In this work we present measurements of mRNA levels of steroid 5α-R isozymes in the ventral prostate of rats of different androgen status. We used a novel method that combines the high specificity of semiquantitive PCR with the sensitivity of laser-induced capillary electrophoresis (LIF-CE). We demonstrated that T control the expression of 5α-R2 isozyme in rat prostrate. This approach could be of great value for the study of prostate diseases in humans and would allow study at the transcriptional level the effects of drugs that inhibit either or both of these isozymes.