Antioxidant enzyme activities,lipid peroxidation,and total antioxidant status in children with Henoch–Schönlein purpura

The aim of this study was to assess the role of oxidative stress in the pathogenesis of Henoch–Schönlein purpura (HSP) vasculitis. The activities of catalase (CAT), arylesterase (ARYL), and paraoxonase (PON) as antioxidant enzymes and serum malondialdehyde (MDA) level as an indicator of lipid peroxidation, together with total antioxidant status (TAS), were measured in 29 children with HSP (mean age 9.3?±?2.7 years), both at the onset of the disease and at the remission period and in matched controls. Active-stage HSP had significantly higher MDA level (15.5?±?7.3 vs 7.8?±?3.9 nmol/l, respectively, P?P?P?=?0.042), ARYL (158?±?39 vs 212?±?52 U/l, P?P?=?0.002) activities compared with the control subjects. Although CAT (P?>?0.05) and PON (P?>?0.05) activities were found to be similar between active and remission stages of HSP, the active stage of the disease had significantly lower ARYL (P?=?0.011) and TAS (P?=?0.006) and higher MDA (P?r?=?0.433, P?=?0.019) and between CAT and C-reactive protein (r?=?0.386, P?=?0.035) in the active stage of HSP. No significant differences were detected in oxidant/antioxidant parameters between patients with or without renal, gastrointestinal, or joint involvement (P?>?0.05). Increased oxidative stress and lipid peroxidation may play important roles in the pathogenesis of HSP vasculitis. Antioxidant therapeutic interventions in long-lasting vasculitis and risk of atherosclerosis secondary to increased oxidant stress remain to be investigated.     

Habitual physical activity and serum lipids: Males,age 16–64 in a total community

More than 1000 males were classified into one of three groups (active, moderately active or sedentary) on the basis of their occupation and leisure time activity. This was done in age specific groups to eliminate the influence of age in the analyses. Blood samples were drawn from these subjects in a non-fasting state. Total cholesterol and triglycerides concentration were determined. Serum cholesterol and, to a lesser extent, serum triglycerides were lower in the active subjects. Diet did not account for the differences. The question was then raised whether the activity-serum relationships would persist if corrected for body fatness of the subjects. The sum of four skinfolds was available as a measure of body fatness. The sum of skinfolds was significantly related to inactivity and the concentration of cholesterol and triglycerides. When corrected for body fatness, there appeared to be little relationship between physical activity and serum lipids.     

Day–night cycles and the sleep-promoting factor,Sleepless, affect stem cell activity in the Drosophila testis

Adult stem cells maintain tissue integrity and function by renewing cellular content of the organism through regulated mitotic divisions. Previous studies showed that stem cell activity is affected by local, systemic, and environmental cues. Here, we explore a role of environmental day–night cycles in modulating cell cycle progression in populations of adult stem cells. Using a classic stem cell system, the Drosophila spermatogonial stem cell niche, we reveal daily rhythms in division frequencies of germ-line and somatic stem cells that act cooperatively to produce male gametes. We also examine whether behavioral sleep–wake cycles, which are driven by the environmental day–night cycles, regulate stem cell function. We find that flies lacking the sleep-promoting factor Sleepless, which maintains normal sleep in Drosophila, have increased germ-line stem cell (GSC) division rates, and this effect is mediated, in part, through a GABAergic signaling pathway. We suggest that alterations in sleep can influence the daily dynamics of GSC divisions.In a constantly changing environment, the transitions between day and night represent the sole nearly invariable component of our living habitat and have influenced the evolution of life since its origin (1). Environmental rhythms in light, either directly or through endogenous circadian clocks, coordinate many biological functions, including gene expression, enzyme activity, and various cellular and behavioral processes (2). One of the most pronounced 24-h cycles, the rhythm in sleep and wakefulness, reflects neuronal activity in the brain and also affects the organism’s systemic milieu, evoking physiological responses in many peripheral tissues (3). In this study, we address possible roles of environmental rhythms and the behavioral status of the organism in regulating cellular homeostasis in adult tissue.Cell renewal is essential for maintaining tissue function over the lifetime of the organism (4). To replace damaged and aging cellular content, comparatively small populations of adult stem cells reside within specialized microenvironments called stem cell niches, where they undergo repeated mitotic divisions, generating new stem and differentiated cells (5). Although the rate of stem cell division is sustained at a tissue and cell type-specific level, an abrupt decrease in the number of cells, caused by physical injury or massive cell death, can initiate a quick response within stem cell populations, leading to increased division activity and thus, enhanced cell production (6). Behavioral factors and environmental influences are also known to affect the frequency of cell divisions, adjusting tissue homeostasis to the changing conditions inside and outside the organism (7). Twenty-four–hour rhythms of division have been documented in several mammalian tissues, reflecting dynamic activity in complex populations of dividing cells consisting of stem cells and their differentiating progeny (8–15). Altered behavioral states, such as insufficient sleep, pregnancy, and physical exercise, induce mitotic activity in the brain and other stem cell-supported tissues (4, 7). However, in most of these studies, stem cells, in particular, were not singled out for analysis, leaving open the question of whether these master regulators are subject to environmental and behavioral influences. To assess this question, we take advantage of a classic Drosophila stem cell system, the spermatogonial stem cell niche, which supports two easily identifiable and thoroughly characterized populations of adult stem cells (16).Located in the apical part of the testis, this niche is formed by a tight cluster of somatic support cells, called the hub, surrounded by germ-line stem cells (GSCs) and cyst progenitor cells (CPCs) (Fig. 1A). Hub cells produce short-range signaling molecules that activate downstream signaling pathways specifically in adjacent stem cells but not in more remotely located cells, thereby confining the stem cell domain in the testis (17). Thus, in contrast to more complex stem cell niches that maintain mammalian tissues, both GSCs and CPCs can be unequivocally identified in vivo and in fixed whole-mount testes based on their position next to the hub and by using simple lineage-specific markers (17) (Fig. 1). GSCs and CPCs self-renew while also generating differentiating cell progeny: gonialblasts and somatic cyst cells, respectively. Gonialblasts enclosed by cyst cell pairs form cysts, the units of sperm development (Fig. 1A). Within cysts, early germ cells continue to amplify, producing 2–16 cell clusters called spermatogonial cells before undergoing meiosis and maturation (16). Molecular communication between the germ line and somatic cell partners ensures proper progression through spermatogenesis (18).Open in a separate windowFig. 1.The spermatogonial stem cell niche and early stages of spermatogenesis in the fly testis. (A) Schematic representation of the niche composed of somatic hub cells (light blue), 5–10 GSCs (peach), and approximately two times as many CPCs (blue). GSCs and CPCs produce differentiating gonialblasts (GBs; yellow) and cyst cells (gray) that form cysts. GBs undergo four additional mitotic divisions to become spermatogonial cells before proceeding into meiosis. (B and C) Single confocal sections show (B, arrowheads) duplicating GSCs and (C, arrow) CPCs. Hub cells are labeled with antibodies against protein Armadillo (membrane green; asterisks). GSCs are positive for a germ cell-specific marker Vasa (red) and positioned immediately next to the hub. CPCs contact hub cells and are Vasa-negative. Antibodies against the phosphorylated form of Histone H3 label mitotic chromatin (nuclear green). DNA counterstain is in blue.Here, we show that, in the presence of environmental day–night cycles, both stem cell populations occupying the Drosophila spermatogonial stem cell niche show daily rhythms in division frequencies that do not persist in constant darkness and thus, do not seem to constitute free-running circadian rhythms. Because sleep–wake rhythms can be driven by environmental cycles, we further address the effect of sleep duration on stem cell activity. Using a combination of genetic and pharmacological assays, we find that loss of the sleep-promoting factor Sleepless (SSS) stimulates GSC division rates in the testis. At least some of the effects of SSS on the GSCs are mediated by reduced GABA levels, which also contribute to the short sleep phenotype. Based on these results, we suggest that some sleep-regulating pathways influence the rate of stem cell division in the fly.     

Does caffeine influence the anticholinesterase and antioxidant properties of donepezil? Evidence from in vitro and in vivo studies

Metabolic Brain Disease - Caffeine is adjudged world’s most consumed pharmacologically active food component. With reports of the potential cognitive enhancing properties of caffeine, we...     

An engineered cell sheet composed of human islets and human fibroblast,bone marrow–derived mesenchymal stem cells,or adipose–derived mesenchymal stem cells: An in vitro comparison study

Background: We previously reported the utility of engineered cell sheets composed of human islets and supporting cells in vitro and in vivo. It is unclear which type of supporting cell is most suitable for constructing cell sheets with human islets. The present study aimed to compare human fibroblasts, bone marrow–derived mesenchymal stem cells (BM–MSCs), and adipose–derived mesenchymal stem cells (ADSCs) as a supporting source for cell sheets.

Methods: Engineered cell sheets were fabricated with human islets using human fibroblasts, BM–MSCs, or ADSCs as supporting cells. The islet viability, recovery rate, glucose–stimulated insulin release (determined by the stimulation index), and cytokine secretion (TGF–β1, IL–6, and VEGF) of groups—including an islet–alone group as a control-were compared.

Results: All three sheet groups consistently exhibited higher viability, recovery rate, and stimulation index values than the islet-alone group. The ADSC group showed the highest viability and recovery rate among the three sheet groups. There were no discernible differences in the stimulation index values of the groups. The fibroblast group exhibited significantly higher TGF–β1 values in comparison to the other groups. The IL–6 level of the ADSC group was more than five times higher than that of the other groups. The ADSC group showed the VEGF level; however, it did not differ from that of the BM–MSC group to a statistically significant extent.

Conclusion: Engineered cell sheets composed of islets and supporting cells had a cytoprotective effect on islets. These results suggest that individual cell types could be a more attractive source for crafting engineered cell sheets in comparison to islets alone.     

Hepatoprotective activity of Sapindus mukorossi and Rheum emodi extracts： In vitro and in vivo studies

AIM： To study the hepatoprotective capacity of Sapindus mukorossi （S. mukorossi） and Rheum emodi （R. emodi） extracts in CCl4 treated male rats. METHODS： The dried powder of S. mukorossi and R. emodi was extracted successively with petroleum ether, benzene, chloroform, and ethanol and concentrated in vacuum. Primary rat hepatocyte monolayer cultures were used for in vitro studies. In vivo, the hepatoprotective capacity of the extract of the fruit pericarp of S. mukorossi and the rhizomes of R. emodi was analyzed in liver injured CCl4-treated male rats. RESULTS： In vitro： primary hepatocytes monolayer cultures were treated with CCl4 and extracts of S. mukorossi ＆ R. emodi. A protective activity could be demonstrated in the CCl4 damaged primary monolayer culture. In vivo ： extracts of the fruit pericarp of S. mukorossi （2.5 mg/mL） and rhizomes of R. emodi （3.0 mg/mL） were found to have protective properties in rats with CCl4 induced liver damage as judged from serum marker enzyme activities. CONCLUSION： The extracts of S. mukorossi and R. emodi do have a protective capacity both in vitro on primary hepatocytes cultures and in in vivo in a rat model of CCl4 mediated liver injury.     

Effects of long DNA folding and small RNA stem–loop in thermophoresis

In thermophoresis, with the fluid at rest, suspensions move along a gradient of temperature. In an aqueous solution, a PEG polymer suspension is depleted from the hot region and builds a concentration gradient. In this gradient, DNA polymers of different sizes can be separated. In this work the effect of the polymer structure for genomic DNA and small RNA is studied. For genome-size DNA, individual single T4 DNA is visualized and tracked in a PEG solution under a temperature gradient built by infrared laser focusing. We find that T4 DNA follows steps of depletion, ring-like localization, and accumulation patterns as the PEG volume fraction is increased. Furthermore, a coil–globule transition for DNA is observed for a large enough PEG volume fraction. This drastically affects the localization position of T4 DNA. In a similar experiment, with small RNA such as ribozymes we find that the stem–loop folding of such polymers has important consequences. The RNA polymers having a long and rigid stem accumulate, whereas a polymer with stem length less than 4 base pairs shows depletion. Such measurements emphasize the crucial contribution of the double-stranded parts of RNA for thermal separation and selection under a temperature gradient. Because huge temperature gradients are present around hydrothermal vents in the deep ocean seafloor, this process might be relevant, at the origin of life, in an RNA world hypothesis. Ribozymes could be selected from a pool of random sequences depending on the length of their stems.     

Selection,proliferation and differentiation of bone marrow-derived liver stem cells with a culture system containing cholestatic serum in vitro

AIM:To explore the feasibility of direct separation,selective proliferation and differentiation of the bone marrow-derived liver stem cells(BDLSC)from bone marrow cells with a culture system containing cholestatic serum in vitro. METHODS:Whole bone marrow cells of rats cultured in routine medium were replaced with conditioning selection media containing 20 mL/L,50 mL/L,70 mL/L,and 100 mL/L cholestatic sera,respectively,after they attached to the plates. The optimal concentration of cholestatic serum was determined according to the outcome of the selected cultures.Then the selected BDLSC were induced to proliferate and differentiate with the addition of hepatocyte growth factor(HGF).The morphology and phenotypic markers of BDLSC were characterized using immunohistochemistry,RT-PCR and electron microscopy.The metabolic functions of differentiated cells were also determined by glycogen staining and urea assay. RESULTS:Bone marrow cells formed fibroblast-like but not hepatocyte-like colonies in the presence of 20 mL/L cholestatic serum.In 70 mL/L cholestatic serum,BDLSC colonies could be selected but could not maintain good growth status.In 100 mL/L cholestatic serum,all of the bone marrow cells were unable to survive.A 50 mL/L cholestatic serum was the optimal concentration for the selection of BDLSC at which BDLSC could survive while the other populations of the bone marrow cells could not.The selected BDLSC proliferated and differentiated after HGF was added.Hepatocyte-like colony-forming units(H-CFU)then were formed.H-CFU expressed markers of embryonic hepatocytes(AFP,albumin and cytokeratin 8/18),biliary cells(cytokeratin 19),hepatocyte functional proteins(transthyretin and cytochrome P450-2b1), and hepatocyte nuclear factors(HNF-1α and HNF-3β).They also had glycogen storage and urea synthesis functions, two of the critical features of hepatocytes. CONCLUSION:The selected medium containing cholestatic serum can select BDLSC from whole bone marrow cells.It will be a new way to provide a readily available alternate source of cells for clinical hepatocyte therapy.     

In vitro activity of ceftazidime-avibactam against Enterobacterales and Pseudomonas aeruginosa isolates collected in Latin America as part of the ATLAS global surveillance program, 2017–2019

The Antimicrobial Testing Leadership and Surveillance (ATLAS) global surveillance program collected clinical isolates of Enterobacterales (n = 8416) and Pseudomonas aeruginosa (n = 2521) from 41 medical centers in 10 Latin American countries from 2017 to 2019. In vitro activities of ceftazidime-avibactam and comparators were determined using the Clinical and Laboratory Standards Institute (CLSI) broth microdilution method. Overall, 98.1% of Enterobacterales and 86.9% of P. aeruginosa isolates were susceptible to ceftazidime-avibactam. When isolates were analyzed by country of origin, susceptibility to ceftazidime-avibactam for Enterobacterales ranged from 97.8% to 100% for nine of 10 countries (except Guatemala, 86.3% susceptible) and from 75.9% to 98.4% for P. aeruginosa in all 10 countries. For Enterobacterales, 100% of AmpC-positive, ESBL- and AmpC-positive, GES-type carbapenemase-positive, and OXA-48-like-positive isolates were ceftazidime-avibactam-susceptible as were 99.8%, 91.8%, and 74.7% of ESBL-positive, multidrug-resistant (MDR), and meropenem-nonsusceptible isolates. Among meropenem-nonsusceptible isolates of Enterobacterales, 24.4% (139/570) carried a metallo-β-lactamase (MBL); 83.3% of the remaining meropenem-nonsusceptible isolates carried another class of carbapenemase and 99.4% of those isolates were ceftazidime-avibactam-susceptible. Among meropenem-non-susceptible isolates of P. aeruginosa (n = 835), 25.6% carried MBLs; no acquired β-lactamase was identified in the majority of isolates (64.8%; 87.2% of those isolates were ceftazidime-avibactam-susceptible). Overall, clinical isolates of Enterobacterales collected in Latin America from 2017 to 2019 were highly susceptible to ceftazidime-avibactam, including isolates carrying ESBLs, AmpCs, and KPCs. Country-specific variation in susceptibility to ceftazidime-avibactam was more common among isolates of P. aeruginosa than Enterobacterales. The frequency of MBL-producers among Enterobacterales from Latin America was low (1.7% of all isolates; 146/8,416), but higher than reported in previous surveillance studies.     

In vitro assessment of the anti-biofilm activity of ethanol alone and in combination with enoxaparin 60 IU

Introduction

Catheter-related bloodstream infection (C-RBSI) can sometimes be managed without catheter removal by combining systemic therapy with catheter lock therapy. Most antiseptic lock solutions are made up of ethanol combined with an anticoagulant. However, data regarding the anti-biofilm activity of ethanol combined with enoxaparin are scarce. We aimed to assess the efficacy of ethanol at different concentrations combined with enoxaparin 60 IU as a lock solution for eradication of the biofilm of different microorganisms.

Evaluation of antihyperglycemic and antioxidant properties of Streblus asper Lour against streptozotocin–induced diabetes in rats

ObjectiveTo evaluate antidiabetic and antioxidant role of methanol extract of Streblus asper (S. asper) root bark in Wistar rats.MethodsDiabetes was induced in rats by single intraperitoneal injection of streptozotocin (STZ, 65 mg/kg body weight). Three days after STZ induction, the diabetic rats were treated with S. asper orally at dose of 200 and 400 mg/kg body weight daily for 15 days. Glibenclamide (0.25 mg/kg, orally) was used as reference drug. The fasting blood glucose levels were measured on every fifth day during the 15-day treatment. Serum biochemical parameters such as serum glutamate pyruvate transaminase, serum glutamate oxaloacetate transaminase, serum alkaline phosphatase, total cholesterol total protein and serum triglycerides were estimated. Antioxidant properties were assessed by estimating liver and kidney thiobarbituric acid reactive substances, reduced glutathione and catalase.ResultsS. asper in STZ-induced diabetic rats, at doses of 200 and 400 mg/kg bw produced reduction in blood glucose levels when compared with the STZ control group. Serum biochemical parameters antioxidant levels were significantly restored toward normal levels in S. asper treated rats as compared with STZ control.ConclusionsThe present study infers that the methanol extract of S. asper root bark demonstrated remarkable antidiabetic activity in STZ-induced diabetic rats. The potential antidiabetic action is plausibly due to its underlying antioxidant role.     

The effect of carnosine treatment on prooxidant–antioxidant balance in liver,heart and brain tissues of male aged rats

Carnosine (β-alanyl-l-histidine) is a dipeptide with antioxidant properties. Oxidative damage by free radicals is one of the mechanisms underlying the aging process. This study was done to investigate the effects of carnosine treatment on lipid peroxidation and antioxidant status of liver, heart, brain in male young and aged rats. At the initiation of study, young and aged rats were 5 and 22 months old, respectively. Carnosine (250 mg/kg, daily, i.p.) was administered for 1 month to rats. At the end of this period, malondialdehyde (MDA) and diene conjugate (DC) and protein carbonyl (PC) levels, glutathione (GSH), vitamin E and vitamin C levels and Cu,Zn-superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and glutathione transferase (GST) activities were determined in tissues of carnosine-treated young and old rats. Liver and heart, but not brain MDA and DC levels increased significantly in aged rats as compared to young rats. Liver PC levels were also significantly elevated. Significant decreases in GSH and vitamin C levels and SOD activities were detected in liver of aged rats, but vitamin E levels and GSH-Px and GST activities remained unchanged. Non-enzymatic and enzymatic antioxidants did not change in heart and brain of aged rats. Carnosine treatment decreased high MDA, DC and PC levels and caused significant increases in vitamin E level and SOD activity in the liver of aged rats. There were no changes in non-enzymatic and enzymatic antioxidants in the heart and brain of carnosine-treated aged rats. In conclusion, carnosine treatment was found to be useful in the decrease of age-related oxidative stress in the liver.     

The antidiabetic effect of Geigeria alata is mediated by enhanced insulin secretion, modulation of β-cell function, and improvement of antioxidant activity in streptozotocin-induced diabetic rats

In Sudanese folk medicine, Geigeria alata roots have been used for the management of diabetes for a long time. However, its antidiabetic activity is unreported. In this study, G. alata methanolic extract was tested for its antidiabetic, antioxidant, and β-cell modulatory effects in a streptozotocin-induced diabetic rat model. In this model of diabetic rats, the oral glucose tolerance test with G. alata extract at 125, 250, and 500?mg/kg doses revealed the efficacy of the 250?mg/kg dose in improving glucose tolerance comparable to the standard drug glibenclamide. Diabetic rats were treated with a 250?mg/kg dose of G. alata extract orally for 2?h (acute) or 14 days (chronic). In the case of acute treatment, the extract lowered blood glucose levels significantly at 120?min both in nondiabetic and diabetic rats. Chronic treatment of diabetic rats with 250?mg/kg of G. alata extract resulted in a significant decrease in blood glucose level closer to that of nondiabetic rats. Interestingly, increased serum insulin, improved β-cell function, and antioxidant status were observed in G. alata-treated diabetic rats. G. alata also showed strong antioxidant and α-glucosidase inhibitory activities in in vitro assays. These data show direct evidence that G. alata has antidiabetic activity and suggest that the antidiabetic activity is due to enhanced insulin secretion, modulation of β-cell function, and improvement of antioxidant status.     

Antimicrobial activity of Sapindus mukorossi and Rheum emodi extracts against H pylori： In vitro and in vivo studies

INTRODUCTION H pylori has infected more than half the population of the world. Most people are unaware that they are infected because they remain asymptomatic throughout life and survive without any harmful infection-related clinical sequelae. However, so…     

Modulatory effects of black tea polyphenols on oxidant–antioxidant profile and expression of proliferation,apoptosis, and angiogenesis-associated proteins in the rat forestomach carcinogenesis model

Background Chemoprevention by dietary constituents has emerged as a novel approach to control stomach cancer incidence. We therefore evaluated the chemopreventive effects of black tea polyphenols (Polyphenon-B) on oxidant–antioxidant status, cell proliferation, apoptosis, and angiogenesis during N-methyl-N′-nitro-N-nitrosoguanidine (MNNG)-induced gastric carcinogenesis. Methods Male Wistar rats were divided into four groups. Rats in group 1 and 2 were given MNNG (150 mg/kg body weight) by intragastric intubation three times at 2 week intervals and followed for 26 weeks. Rats in group 2 received in addition a basal diet containing 0.05% Polyphenon-B. Group 3 animals were given 0.05% Polyphenon-B alone. Group 4 animals served as controls. The status of lipid peroxidation and antioxidants and the expression of the lipid peroxidation marker 4-hydroxy nonenal (4-HNE), proliferating cell nuclear antigen (PCNA), glutathiones-transferase (GST)-π, Bcl-2, Bax, cytochrome C, caspase 3, cytokeratins, and vascular endothelial growth factor (VEGF) were used as biomarkers. Results Intragastric administration of MNNG induced well-differentiated squamous cell carcinomas that showed diminished lipid and protein oxidation and an increase in antioxidant status. This was associated with increased cell proliferation, angiogenesis, and invasive potential coupled with apoptosis evasion as revealed by upregulation of PCNA, GST-π, Bcl-2, cytokeratins, and VEGF and downregulation of Bax, cytochrome C, and caspase 3 protein expression. Dietary administration of Polyphenon-B effectively suppressed MNNG-induced gastric carcinogenesis, as evidenced by modulation of oxidant–antioxidant status, inhibition of cell proliferation and infiltration, and angiogenesis associated with apoptosis induction. Conclusions The present study provides evidence that Polyphenon-B exerts multifunctional inhibitory effects on MNNG-induced gastric carcinogenesis and suggests that it can be developed as a potential chemopreventive agent.     

Immunopresence and enzymatic activity of nitric oxide synthases, cyclooxygenases and PGE2-9-ketoreductase and in vitro production of PGF2α, PGE2 and testosterone in the testis of adult and prepubertal alpaca (Lama pacos)

This study presents the first evidence for differences in COXs, PGE2-9-ketoreductase and NOSs immunopresence and enzyme activity, and prostaglandin and testosterone production between the testes of adult and prepubertal alpacas. The prepubertal testis immunohistochemical data revealed that COX1 was expressed in spermatogonia and endothelial cells whereas COX2 was present only in the stromal cells. In adult animals, COX2 immunosignals were evidenced in germ cells, as well as both COX1 and -2 in Leydig and Sertoli cells. In adult testes, the spermatogonia, spermatocytes and round spermatids had expression of e- and n-NOS only, whereas elongated spermatids exhibited immunopositivity for i- and e-NOS and Sertoli cells expressed only n-NOS. In prepubertal alpacas, i-NOS was localized in spermatogonia, e-NOS in Sertoli cells and all three NOS isoforms in Leydig cells. PGE2-9-ketoreductase immunopresence was observed in spermatogonia nuclei and cytoplasm of prepubertal testis whereas they were localized in spermatid acrosomal vesicle of adult. The enzymatic data indicated that COX1 activity was higher than COX2 in adult alpaca testis whereas the activity of COX2 was greater than that of COX1 in prepubertal animals. Total NOS and PGE2-9-ketoreductase activities were more extensive in adult alpacas. In vitro hormone production results showed that prepubertal testes released lower amounts of testosterone and PGF2α while PGE2 synthesis was six times more elevated than in in vitro incubated adult testes. Taken together, the data on COX2, i-NOS and PGE2 led us to hypothesize that development in prepubertal male reproductive tissues utilizes a mechanism similar to that of inflammation.