Mitochondrial Quality Control in the Heart: New Drug Targets for Cardiovascular Disease

Despite considerable efforts to prevent and treat cardiovascular disease (CVD), it has become the leading cause of death worldwide. Cardiac mitochondria are crucial cell organelles responsible for creating energy-rich ATP and mitochondrial dysfunction is the root cause for developing heart failure. Therefore, maintenance of mitochondrial quality control (MQC) is an essential process for cardiovascular homeostasis and cardiac health. In this review, we describe the major mechanisms of MQC system, such as mitochondrial unfolded protein response and mitophagy. Moreover, we describe the results of MQC failure in cardiac mitochondria. Furthermore, we discuss the prospects of 2 drug candidates, urolithin A and spermidine, for restoring mitochondrial homeostasis to treat CVD.

Decreased plasmatic spermidine and increased spermine in mild cognitive impairment and Alzheimer's disease patients

Abstract Background Current evidence suggests that upregulation of polyamines system plays a role both in cognitive deficit and synaptic loss observed in Alzheimer's disease (AD). Objective The aim of this study was to determine the plasmatic concentration of polyamines in mild cognitive impairment (MCI) and AD patients in comparison with healthy controls (HC). Methods Plasmatic polyamines were quantified using the AbsoluteIDQ® p180 and liquid chromatography coupled to tandem mass spectrometry (LC/MS-MS). Results The study group comprised 34 AD patients, 20 MCI and 25 HC. All individuals were followed for 4 years. During this period 8 amnestic MCI patients (40% of the MCI sample at baseline) converted to AD. Spermidine level was lower in both patient groups (AD; MCI) compared to HC (p = 0.007). Plasma levels of spermine were higher in the MCI group (p < 0.001), but decreased in the sub-sample of MCI patients who converted to AD (p = 0.043). No statistically significant differences were found in ornithine and putrescine levels (p = 0.056 and p = 0.126, respectively). Discussion Our results suggest dynamic changes in the expression of polyamines in the MCI-AD continuum.

Exogenous spermidine ameliorates tubular necrosis during cisplatin nephrotoxicity / 대한해부학회지

The hallmark of cisplatin-induced acute kidney injury is the necrotic cell death in the kidney proximal tubules. However, an effective approach to limit cisplatin nephrotoxicity remains unknown. Spermidine is a polyamine that protects against oxidative stress and necrosis in aged yeasts, and the present study found that exogenous spermidine markedly attenuated tubular necrosis and kidney dysfunction, but not apoptosis, during cisplatin nephrotoxicity. In addition, exogenous spermidine potently inhibited oxidative/nitrative DNA damage, poly(ADP-ribose) polymerase 1 (PARP1) activation and ATP depletion after cisplatin injection. Conversely, inhibition of ornithine decarboxylase (ODC) via siRNA transfection in vivo significantly increased DNA damage, PARP1 activation and ATP depletion, resulting in acceleration of tubular necrosis and kidney dysfunction. Finally, exogenous spermidine removed severe cisplatin injury induced by ODC inhibition. In conclusion, these data suggest that spermidine protects kidneys against cisplatin injury through DNA damage and tubular necrosis, and this finding provides a novel target to prevent acute kidney injury including nephrotoxicity.

Spermidine Protects against Oxidative Stress in Inflammation Models Using Macrophages and Zebrafish

Spermidine is a naturally occurring polyamine compound that has recently emerged with anti-aging properties and suppresses inflammation and oxidation. However, its mechanisms of action on anti-inflammatory and antioxidant effects have not been fully elucidated. In this study, the potential of spermidine for reducing pro-inflammatory and oxidative effects in lipopolysaccharide (LPS)-stimulated macrophages and zebrafish was explored. Our data indicate that spermidine significantly inhibited the production of pro-inflammatory mediators such as nitric oxide (NO) and prostaglandin E2 (PGE2), and cytokines including tumor necrosis factor-α and interleukin-1β in RAW 264.7 macrophages without any significant cytotoxicity. The protective effects of spermidine accompanied by a marked suppression in their regulatory gene expression at the transcription levels. Spermidine also attenuated the nuclear translocation of NF-κB p65 subunit and reduced LPS-induced intracellular accumulation of reactive oxygen species (ROS) in RAW 264.7 macrophages. Moreover, spermidine prevented the LPS-induced NO production and ROS accumulation in zebrafish larvae and was found to be associated with a diminished recruitment of neutrophils and macrophages. Although more work is needed to fully understand the critical role of spermidine on the inhibition of inflammation-associated migration of immune cells, our findings clearly demonstrate that spermidine may be a potential therapeutic intervention for the treatment of inflammatory and oxidative disorders.

A useful procedure for detection of polyamines in biological samples as a potential diagnostic tool in cancer diagnosis

Background: Polyamines present in human body are frequently considered as markers of occurrence of cancer. Therefore, the availability of simple and efficient method for determination of their level in body liquids and tissues is of some interest. Methods: Supported liquid membrane technology coupled with HPLC seems to be an appropriate technique to follow the level of polyamines in human blood and urine. Thus, the membranes of two different geometries: flat sheet and hollow fiber were studied as a mean for separation and enrichment of studied polyamines from urine and tissue samples in order to prepare samples to be analyzed by HPLC. Conclusions: Developed extraction systems offer an interesting alternative to traditional techniques such as: liquid-liquid or solid-phase extraction due to several features, which are: very high enrichment of polyamines without previous work-up, simple procedure of extraction and tiny volume of organic solvents used. This enables efficient determination of their levels in body liquids (AU)

Spermidine is protective against kidney ischemia and reperfusion injury through inhibiting DNA nitration and PARP1 activation / 대한해부학회지

Kidney ischemia and reperfusion injury (IRI) is associated with a high mortality rate, which is attributed to tubular oxidative and nitrative stresses; however, an effective approach to limit IRI remains elusive. Spermidine, a naturally occurring polyamine, protects yeast cells against aging through the inhibition of oxidative stress and necrosis. In the present study, spermidine supplementation markedly attenuated histological damage and kidney dysfunction during IRI. In addition, exogenous spermidine potently inhibited poly(ADP-ribose) polymerase 1 (PARP1) activation and DNA nitrative/oxidative stress following IRI. Conversely, inhibition of ornithine decarboxylase (ODC) via siRNA transfection in vivo significantly enhanced DNA nitration, PARP1 activation, and functional damage during IRI. Finally, in ODC knockdown kidneys, PARP1 inhibition attenuated histological and functional damage induced by IRI, but not DNA nitrative stress. In conclusion, these data suggest that spermidine protects kidneys against IRI through blocking DNA nitration and PARP1 activation and this finding provides a novel target for prevention of acute kidney injury including IRI.

Identification of Wild Yeast Strains and Analysis of Their beta-Glucan and Glutathione Levels for Use in Makgeolli Brewing

Makgeolli, also known as Takju, is a non-filtered traditional Korean alcoholic beverage that contains various floating matter, including yeast cells, which contributes to its high physiological functionality. In the present study, we assessed the levels of beta-glucan and glutathione in various yeast strains isolated from traditional Korean Nuruk and selected a beta-glucan- and glutathione-rich yeast strain to add value to Makgeolli by enhancing its physiological functionality through increased levels of these compounds. Yeast beta-glucan levels ranged from 6.26% to 32.69% (dry basis) and were strongly species-dependent. Dried Saccharomyces cerevisiae isolated from Nuruk contained 25.53 microg/mg glutathione, 0.70 microg/mg oxidized glutathione, and 11.69 microg/g and 47.85 microg/g spermidine and L-ornithine monohydrochloride, respectively. To produce functional Makgeolli, a beta-glucan- and glutathione-rich yeast strain was selected in a screening analysis. Makgeolli fermented with the selected yeast strain contained higher beta-glucan and glutathione levels than commercial Makgeolli. Using the selected yeast strain to produce Makgeolli with high beta-glucan and glutathione content may enable the production of functional Makgeolli.

Polyamines and Their Metabolites as Diagnostic Markers of Human Diseases

Polyamines, putrescine, spermidine and spermine, are ubiquitous in living cells and are essential for eukaryotic cell growth. These polycations interact with negatively charged molecules such as DNA, RNA, acidic proteins and phospholipids and modulate various cellular functions including macromolecular synthesis. Dysregulation of the polyamine pathway leads to pathological conditions including cancer, inflammation, stroke, renal failure and diabetes. Increase in polyamines and polyamine synthesis enzymes is often associated with tumor growth, and urinary and plasma contents of polyamines and their metabolites have been investigated as diagnostic markers for cancers. Of these, diacetylated derivatives of spermidine and spermine are elevated in the urine of cancer patients and present potential markers for early detection. Enhanced catabolism of cellular polyamines by polyamine oxidases (PAO), spermine oxidase (SMO) or acetylpolyamine oxidase (AcPAO), increases cellular oxidative stress and generates hydrogen peroxide and a reactive toxic metabolite, acrolein, which covalently incorporates into lysine residues of cellular proteins. Levels of protein-conjuagated acrolein (PC-Acro) and polyamine oxidizing enzymes were increased in the locus of brain infarction and in plasma in a mouse model of stroke and also in the plasma of stroke patients. When the combined measurements of PC-Acro, interleukin 6 (IL-6), and C-reactive protein (CRP) were evaluated, even silent brain infarction (SBI) was detected with high sensitivity and specificity. Considering that there are no reliable biochemical markers for early stage of stroke, PC-Acro and PAOs present promising markers. Thus the polyamine metabolites in plasma or urine provide useful tools in early diagnosis of cancer and stroke.

Dynamin-mediated endocytic process contributes to neuronal nitric oxide synthase-mediated regulation of cardiac contraction / 生理学报

Nitric oxide synthases (NOSs) play complex roles in the regulation of cardiac excitation contraction coupling under basal and stressed conditions. Herein, using the recording approach for intracellular calcium transient and synchronous myocyte contraction, the potential mechanism for NOSs-mediated cardiomyocyte contraction was explored. We found that selective inhibition of neuronal NOS (nNOS) with 100 µmol/L spermidine markedly enhanced the cardiomyocyte twitch [control: (10.5 ± 0.21)%; nNOS inhibition: (12.4 ± 0.18)%] and calcium transient [control: (0.27 ± 0.03)%; nNOS inhibition: (0.42 ± 0.01)%], but slowed the relengthening of twitch [control: (25.2 ± 1.3) ms; nNOS inhibition: (53 ± 2.8) ms] and the calcium transient decay [control: (129 ± 4.3) ms; nNOS inhibition: (176 ± 7.1) ms], which was similar to that by dynamin inhibition with 30 µmol/L dynasore. The nNOS inhibition- or dynasore-mediated effects could be rescued by an NO donor, S-Nitroso-N-acetylpenicillamine (SNAP). Our data suggest that the selective nNOS-mediated regulation of cardiac contractile activity may partly involve the dynamin-mediated endocytic mechanism.

Effect of exogenous Ca2+, ALA, SA and Spd on seed germination and physiological characteristics of Perilla frutescens seedlings under NaCl stress / 中国中药杂志

<p><b>OBJECTIVE</b>To find a method for improving the salt resistance of seeds and seedlings for Perilla Frutescens under NaCl stress, seed germination and physiological characteristics of P. frutescens seedlings were studied.</p><p><b>METHOD</b>Several physiological indexes of P. frutescens seeds treated with different concentrations of Ca2+, 5-aminolevulinic acid (ALA), salicylic acid (SA) and spermidine (Spd) under NaCl stress like the germination vigor, germination rate, germination index and vigor index were measured. And other indexes like the biomass of the seedlings, the content of malondialdehyde (MDA) in leaves, the activities of superoxide (SOD), peroxidase (POD) and catalase (CAT) were also measured.</p><p><b>RESULT</b>The germination of P. frutescens seeds under NaCl stress (100 mmol x L(-1)) was inhibited obviously. But after the treatment with Ca2+, ALA , SA and Spd, all germination indexes were increased. Ca2+ (10 mmol x L(-1)), ALA (100 mg x L(-1)), SA (50 mg x L(-1)) and Spd (0.25 mmol x L(-1)) could obviously alleviate the damage of salt stress to the seeds of P. frutescens. ALA (100 mg x L(-1)) significantly increased all indexes. The germination vigor was 65.3%, the germination rate was 89.7%, the germination index and vigor index were 15.2 and 0.1238, respectively. All treatments decreased the content of MDA in leaves. The activities of three enzymes including SOD, POD and CAT were all increased. ALA (100 mg x L(-1)) had the enzymes activity reach the maximum with 0.72, 6, 82 and 5.64 U x mg(-1), respectively.</p><p><b>CONCLUSION</b>Ca2+ ALA , SA and Spd with appropriate concentration could significantly alleviate the damages to the seeds and seedlings of P. frutescens under NaCl stress and promote the salt resistance of the seeds and seedlings.</p>

Apoptosis induced by NNAMB, a novel polyamine conjugate, in human erythroleukemia K562 cells and its mechanism / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To investigate the apoptosis-inducing effects of NNAMB, a novel polyamine conjugate, in erythroleukemia K562 cells and its molecular mechanism.</p><p><b>METHODS</b>Cell viability was assessed by MTT assay and trypan blue dye exclusion method. The cell morphology was observed by fluorescence microscopy. The cell cycle distribution, apoptosis and mitochondrial membrane potential were measured by flow cytometry. The expression of caspase-3, -8, -9, cytochrome c in the K562 cells was detected by Western blot.</p><p><b>RESULTS</b>NNAMB inhibited the proliferation of K562 cells. The cells treated with NNAMB showed a typical apoptotic morphology, Sub-G1 peak and loss of mitochondrial membrane potential. Western blot assay showed that NNAMB increased the expression of caspase-3, -9, cytochrome c but not caspase-8 in a dose-and time-dependent manner.</p><p><b>CONCLUSION</b>NNAMB induces apoptosis via mitochondrial pathway in K562 cells.</p>

Relaxant Effect of Spermidine on Acethylcholine and High K+-induced Gastric Contractions of Guinea-Pig

In our previous study, we found that spermine and putrescine inhibited spontaneous and acetylcholine (ACh)-induced contractions of guinea-pig stomach via inhibition of L-type voltage- dependent calcium current (VDCCL). In this study, we also studied the effect of spermidine on mechanical contractions and calcium channel current (IBa), and then compared its effects to those by spermine and putrescine. Spermidine inhibited spontaneous contraction of the gastric smooth muscle in a concentration-dependent manner (IC50=1.1+/-0.11 mM). Relationship between inhibition of contraction and calcium current by spermidine was studied using 50 mM high K+-induced contraction: Spermidine (5 mM) significantly reduced high K+(50 mM)-induced contraction to 37+/-4.7% of the control (p<0.05), and inhibitory effect of spermidine on IBa was also observed at a wide range of test potential in current/voltage (I/V) relationship. Pre- and post-application of spermidine (5 mM) also significantly inhibited carbachol (CCh) and ACh-induced initial and phasic contractions. Finally, caffeine (10 mM)-induced contraction which is activated by Ca2+-induced Ca2+release (CICR),` was also inhibited by pretreatment of spermidine (5 mM). These findings suggest that spermidine inhibits spontaneous and CCh-induced contraction via inhibition of VDCCL and Ca2+releasing mechanism in guinea-pig stomach.

Teores de poliaminas em alguns alimentos da dieta básica do povo brasileiro / Polyamines contents in some foods from Brazilian population basic diet

Os teores de poliaminas variam, assim como a sua necessidade, por estarem relacionadas diretamente com o crescimento de células. Neste estudo, foram analisados os teores de putrescina, espermidina e espermina em diversos alimentos de origem vegetal e em ovos. O cozimento não afetou os teores em arroz ou feijão, porém em batata inglesa houve diferença, sendo que a fritura incrementou o teor principalmente de putrescina. Alface, laranja, banana e tomate apresentaram teores de putrescina maiores, enquanto que em cebola, alho, ovos, arroz e feijão houve predominância de espermidina e espermina. Estes resultados são relevantes para uma possível elaboração da dieta de muitas pessoas, dependendo da sua necessidade diária.

Influence of cytokinins, auxins and polyamines on in vitro mass multiplication of cotton (Gossypium hirsutum L. cv. SVPR2).

In the present investigation, the influence of different forms of cytokinins, auxins and polyamines were tested for mass multiplication and regeneration of cotton. Initially, for the identification of effective concentration for multiple shoot induction, various concentrations of BAP, Kin and 2iP along with IAA and NAA were tested. Among tested concentrations, media fortified with MS salts; B5 vitamins; 30 g/l, glucose; 2.0 mg/l, 2iP; 2.0 mg/l, IAA and 0.7 % agar showed best response for multiplication of shoot tip explants (20 shoots per shoot tip explants). In nodal explants, maximum of 18.6 shoots were obtained in the media fortified with MS salts, B5 vitamins, 30 g/l, glucose, 2.0 mg/l, 2iP, 1.0 mg/l, NAA and 0.7 % agar. Effect of different concentrations of polyamines like spermidine and putrescine were also tested along with the above said multiplication media. Among the various treatments, 20 mg/l of putrescine showed best response and the multiple of shoots were increased to 26.5 shoots per shoot tip explants and 24.5 shoots per nodal explants. Elongation of shoots was achieved on multiple shoot induction medium. Significant number of roots were initiated in the medium supplemented with MS salts, vitamin B5 and IBA (2.0 mg/l). The frequency of root induction was increased by addition of, PVP (10 mg/l) along with root induction medium and after 2 weeks, the roots reached the maximum length of 22 cm. Further, these plantlets were hardened by using sand, soil and vermiculate in 1:1:1 ratio. The hardened plants were transferred to the environmental growth chamber for proper acclimatization. The hardened plants were then transferred to field for boll yielding and they exhibited 100% survival.

Intracellular polyamine pools, oligopeptide-binding protein A expression, and resistance to aminoglycosides in Escherichia coli

The role of intracellular free polyamine (putrescine and spermidine) pools in multiple resistance to aminoglycoside antibiotics was investigated among in vitro selected kanamycin-resistant Escherichia coli J53 mutants expressing diminished oligopeptide-binding protein (OppA) levels and/or defective ornithine decarboxylase (ODC) activity. The results suggest that diminished OppA content, but not defective ODC activity expression, increased the relative concentration of free spermidine as compared to the wild type strain. Moreover, by adding exogenous polyamines or polyamine synthesis inhibitors to cultures with different mutant strains, a direct relationship between the intracellular OppA levels and resistance to kanamycin was revealed. Collectively these results further suggest a complex relation among OppA expression, aminoglycoside resistance and polyamine metabolism.

Relaxation Responses of Isolated Rabbit Seminal Vesicle to Polyamines / 대한비뇨기과학회지

PURPOSE: This study was designed to investigate the effects of polyamines on rabbit seminal vesicular contractility. MATERIALS AND METHODS: The polyamines; putrescine, spermidine and spermine, were added to deepithelized and precontracted seminal vesicle strips, with either 10 4M norepinephrine (NE), 10 4M acetylcholine (ACh) or 70mM KCl, in organ chambers to obtain cumulative concentration response curves. A whole cell mode patch clamp study was also performed to observe the effects of the polyamines on the L-type calcium channel activities. RESULTS: The polyamines elicited concentration-dependent relaxations of the precontracted strips with the NE, ACh and KCl. The spermine showed the most potent relaxation response. Both extracellular and intracellular application of the spermine decreased the L-type calcium channel currents. CONCLUSIONS: Spermine more potently inhibited the seminal vesicle contraction than putrescine or spermidine, which suggests the polyamines may play a role in maintaining the basal tonicity of seminal vesicle in a flaccid state. The spermine-induced relaxation response seems to be related with an inhibition of the L-type calcium channel activities.

Effect of diethylstilbestrol on polyamine metabolism in hamster epididymis / 亚洲男科学杂志(英文版)

<p><b>AIM</b>To investigate the effect of diethylstilbestrol (DES), one of the most potent endocrine disruptors, on the metabolism of polyamines in hamster epididymis.</p><p><b>METHODS</b>Male golden hamsters of 7-week-old were kept under a light and dark cycle of 14 h and 10 h for 1 week to stimulate maximally the gonadal function. DES was injected subcutaneously at doses of 0.01 mg . kg(-1) . day(-1), 0.1 mg . kg(-1) . day(-1) and 1 mg . kg(-1) . day(-1) for one week.</p><p><b>RESULTS</b>DES treatment caused a significant decrease in the weight of epididymis. The activity of epididymal ornithine decarboxylase (ODC) increased 1 day after DES treatment, kept at a high level for 4 days and then decreased to nearly normal level at day 7. The activity of spermidine/spermine N1-acetyltransferase (SSAT) also increased transiently after DES treatment. The contents of putrescine, spermidine, spermine and N(1)-acetylspermidine were increased 1 day approximately 4 days after DES treatment and restored to normal at day 7. All these changes showed a marked difference between the caput and the cauda.</p><p><b>CONCLUSION</b>The polyamine biosynthesis in the hamster epididymis can be affected by DES, a xenoestrogen. DES may probably affect polyamine metabolism in the epididymis by regulating the rate-limiting enzymes involved in the polyamine biosynthesis.</p>

Changes in free polyamines and related enzymes during stipule and pod wall development in Pisum sativum.

Level of free polyamines, their key metabolic enzymes, and other features related to ageing were examined during stipule and pod wall development in pea (Pisum sativum). Free polyamine titre (per unit fresh mass) in both the organs, the specific activities of arginine decarboxylase and ornithine decarboxylase in the pod wall, gradually decreased with maturation. In stipule, these enzymes attained peak activity at 15 days after pod emergence and declined thereafter. Ornithine decarboxylase activity was greater in pod wall than in stipule; while, arginine decarboxylase activity was higher in stipule. Activity of degradative enzyme diamine oxidase increased with the onset of senescence in both the organs. Chlorophyll and electrical conductance had a inverse relationship throughout the experimental period, whereas, the chlorophyll content was directly related with polyamine levels in both stipule and pod wall during aging. On the other hand, protein and RNA contents were positively correlated with free polyamines throughout the test period in stipule, but in the pod wall this was true only for the later stages of development.

Effect of Melatonin on Brain Polyamine Contents and Hippocampal Neuronal Damage after Transient Global Ischemia in Mongolian Gerbil / 대한뇌혈관학회지

OBJECTIVES: This study was designed to examine whether melatonin has a neuroprotective effect against hippocampal neuronal damage following transient global ischemia in a gerbil. Polyamine is known to play a role in the pathophysiology of ischemic neuronal damage, we evaluated the influences of melatonin on the polyamine level as well as histology. MATERIAL AND METHODS: Male Mongolian gerbils (60-80 g) were used in this study. Transient global ischemia was induced by occlusion of the bilateral common carotid arteries for 3 min with microclips. Melatonin was administered immediately after occlusion. The animals were decapitated 24 h after the occlusion for polyamine measurement by a high performance liquid chromatography (HPLC) and 4 days after the occlusion for histological evaluation (hematoxylin and eosin staining). A histological examination was performed by a blinded investigator. RESULTS: The hippocampal putrescine level increased compared to sham-operated animals and the increase of putrescine was attenuated by 20 mg/kg melatonin administration. Spermidine and spermine levels didn't show significant changes after ischemia. Hippocampal neuronal damage in the CA1 region was markedly observed in vehicle-treated animals compared to sham-operated animals. Melatonin administration (10 or 20 mg/kg) significantly inhibited hippocampal CA1 neuronal damage after ischemia compared to corresponding vehicle-treated animals (p<0.05 and p<0.01, respectively). CONCLUSION: Melatonin attenuates the putrescine level after transient global ischemia and may have putative neuroprotective effects against global ischemia induced neuronal damage.

Cambios en la actividad de arginasa pancreática en ratas púberes y adultas inducidos por la castración / Activity pancreatic arginase changes inducted by castration in pubescent and adult rats

La actividad de arginasa en riñón e intestino delgado en algunas especies de mamíferos es sensible a la castración, un hallazgo que puede sugerir su dependencia de testosterona. Sin embargo, hasta donde conocemos, la información sobre la regulación de la actividad de arginasa pancreática es escasa. En este trabajo se estudió el efecto de la orquidectomía sobre la actividad de arginasa pancreática en ratas púberes y adultas. Las ratas púberes y adultas, de 21 días y 4 meses de edad, respectivamente, fueron orquidectomizadas y sacrificadas a varios tiempos después de la cirugía. Grupos de ratas intactas sirvieron como controles. La actividad de arginasa y las proteínas fueron determinadas en tejido pancreático. En suero, la actividad de la enzima fue determinada en adición a la glucosa, los triglicéridos y las proteínas totales. En las ratas la actividad de arginasa pancreática y sérica mostró un pico el día 5 poscirugía, mientras que en las adultas, se observó un aumento en la actividad de arginina el día 20. Se observaron cambios en las proteínas séricas y pancreáticas en ratas púberes castradas, pero no en las adultas. Estos resultados sugieren que la arginasa pancreática es dependiente de andrógenos, y que hay diferencia de edades, probablemente debido a patrones distintos de secreción hormonal en ratas adultas y púberes.