Rat Thymocytes Research Articles

A comparison of the cellular actions of polaprezinc (zinc-l-carnosine) and ZnCl2

AimsZinc supplementation has been proven to be beneficial for the prevention of some health problems. Many zinc supplements are used for medical and nutritional purposes. However, it is difficult to distinguish between them in terms of their cellular actions. We compared the cellular actions of polaprezinc (zinc-l-carnosine) with those of ZnCl2 in order to determine whether polaprezinc has greater zinc-related actions than ZnCl2. Main methodsCellular actions of polaprezinc and ZnCl2 were estimated by flow-cytometric techniques with appropriate fluorescent probes in rat thymocytes. Key findingsBoth agents had almost equal stimulatory effects on the intracellular Zn2+ level and cellular level of nonprotein thiol in a similar concentration-dependent manner. However, the increase in cell lethality caused by ZnCl2 under severe oxidative stress was significantly greater than that caused by polaprezinc. SignificanceThere are various zinc supplements, for example, zinc gluconate, zinc picolinate, and zinc methionine. However, the differences in their cellular actions have not been elucidated to date. Such studies could distinguish between zinc supplements.

A Historical Perspective on Sepsis

In North America, approximately 700,000 cases of sepsis occur each year, with mortality ranging between 30% and 50%. The American Journal of Pathology has featured numerous articles on the topic, revealing mechanistic insights gleaned from both experimental rodent models and human sepsis. Nonetheless, there remains urgent need to determine the basis for sepsis-related complications and how they can be avoided, as well as how they can be most effectively treated once recognized. This historical perspective reviews what we currently understand about the mechanisms of sepsis, as well as the barriers that remain in our treatment strategies.

Effect of four lichen acids isolated from Hypogymnia physodes on viability of rat thymocytes

Four lichen acids, physodalic acid (F1), physodic acid (F2), 3-hydroxyphysodic acid (F3), and isophysodic acid (F4), were isolated from Hypogymnia physodes methanol extract using preparative reversed-phase high performance liquid chromatography and their structures were determined by UV, MS, 1H NMR and 13C NMR. This is the first report on the isolation of F4 from H. physodes. Isolated rat thymocytes were cultivated with increasing F1–F4 concentrations (0.1, 1, 10μg/well) and proliferative activity, viability, ROS (reactive oxygen species) production and MMP (mitochondrial membrane potential) disturbances were evaluated. Obtained results show significantly decreased thymocytes proliferation was observed when cells were treated with F1 (1μg, p<0.05; 10μg; p<0.001), F2 (10μg, p<0.05) and F3 compound (10μg, p<0.05). Significantly increased cytotoxicity was detected when cells were incubated with F1 (1μg, p<0.05; 10μg, p<0.01), F2 (10μg, p<0.05) and F3 compound (10μg, p<0.001). Increased H2DCF-DA fluorescence intensity, when cells were treated with F1 (1μg, p<0.001; 1μg, p<0.01; 10μg, p<0.001) and F2 (1μg, p<0.05; 10μg, p<0.01) compound, indicating the increase of intracellular ROS production. Simultaneously, increased ROS levels were followed with significantly decreased MMP when thymocytes were cultivated with F1 (0.1μg, p<0.001; 1μg, p<0.001; 10μg, p<0.001) and F2 compound (10μg, p<0.001). Thymocytes exposure to increased (0.1, 1, 10μg) concentrations of F3 and F4 compounds did not result with significant alterations in MMP and intracellular ROS production. We have shown that higher F1 and F2 concentrations induce thymocytes toxicity mainly through induction of oxidative stress, while cytotoxicity effect of F3 is followed with altered antioxidant/oxidant balance. The rigid 11H-dibenzo[b,e][1,4]dioxepin-11-one ring in the depsidone structure may play a important role for the examined biological activities.

Nanomolar concentrations of zinc pyrithione increase cell susceptibility to oxidative stress induced by hydrogen peroxide in rat thymocytes

Zinc pyrithione is used as an antifouling agent. However, the environmental impacts of zinc pyrithione have recently been of concern. Zinc induces diverse actions during oxidative stress; therefore, we examined the effect of zinc pyrithione on rat thymocytes suffering from oxidative stress using appropriate fluorescent probes. The cytotoxicity of zinc pyrithione was not observed when the cells were incubated with 3μM zinc pyrithione for 3h. However, zinc pyrithione at nanomolar concentrations (10nM or more) significantly increased the lethality of cells suffering from oxidative stress induced by 3mM H2O2. The application of zinc pyrithione alone at nanomolar concentrations increased intracellular Zn2+ level and the cellular content of superoxide anions, and decreased the cellular content of nonprotein thiols. The simultaneous application of nanomolar zinc pyrithione and micromolar H2O2 synergistically increased the intracellular Zn2+ level. Therefore, zinc pyrithione at nanomolar concentrations may exert severe cytotoxic action on cells simultaneously exposed to chemicals that induce oxidative stress. If so, zinc pyrithione leaked from antifouling materials into surrounding environments would be a risk factor for aquatic ecosystems. Alternatively, zinc pyrithione under conditions of oxidative stress may become more potent antifouling ingredient.

Proteomic profiling of rapid non-genomic and concomitant genomic effects of acute restraint stress on rat thymocytes

In order to investigate rapid non-genomic effects of acute stress, rats were restrained for 15 min which was sufficient to activate the hypothalamus-pituitary-adrenal (HPA) axis but too short to induce massive genomic effects of cortisol. Subcellular fractions of thymocytes (cytosol, nucleus, membrane) were investigated using quantitative 2D DIGE with MALDI-TOF/TOF mass spectrometry. In total, 108 proteins with differential subcellular localizations were identified. The specificity of the changes induced by psychological stress was reflected by the prominent modulation of proteins involved in the HPA and sympathoadrenal medullar (SAM) axis such as HMGB1 and NHERF1. Intracellular trafficking was characterized by a dominant protein exodus from the cytosol. Real translocation was observed for 9 proteins with 6 that shuttled from the cytosol to the nucleus (HYOU1, HNRPF, HNRPC, STRAP, PSA1, PPA1) and 3 from the nucleus to the cytosol (HMGB1, NHERF1, PSMA1). Proteins showing subcellular reshuffling were largely involved in transcription and translation processes (39 of 108) with a significant enrichment of RNA splicing factors. Bioinformatics analysis revealed significant enrichment for protein kinase A and 14-3-3 signaling, probably reflecting real non-genomic effects. This is the first study investigating rapid effects of stress-induced HPA activation in vivo at the proteome level.

Protective role of vitamin C in diazepam-induced apoptosis in rat thymocytes

Diazepam, a peripheral-type benzodiazepine receptor ligand, is widely used as a therapeutic agent. On the other hand, peripheral-type benzodiazepines have been shown to induce apoptosis in different immune cell types. In this study, we examined the possible protective role of vitamin C in diazepam-induced apoptosis and evaluated the cellular content of glutathione during this process. Rat thymocytes were incubated for 24 hours with diazepam and increasing concentrations of vitamin C or with diazepam alone. The exposure to diazepam resulted in an increase in apoptotic cell death and decrease in glutathione content in rat thymocytes. Vitamin C was effective in ameliorating the effect of diazepam in rat thymocytes by decreasing the proportion of apoptotic cells and increasing the cellular content of glutathione. These results suggest that vitamin C reduced the diazepam-induced apoptosis in rat thymocytes by restoring the cellular content of glutathione, which may be useful in preventing the diazepam-induced immunosupression (Tab. 1, Fig. 1, Ref. 31).

Effect of garlic consumption on the argyrophilic nucleolar organiser regions (AgNORs) in splenocytes and thymocytes of rats

The number and size of nucleolar organiser regions (NORs) are related to cell proliferation. To test the hypothesis that lymphocyte proliferation is associated with garlic consumption, 17 6-week-old male Wistar rats were separated into two groups. For 30 days eight rats were given garlic solution by gavage while the remaining nine animals received distilled water. Silver staining of NORs was performed on the fixed tissues of spleens and thymuses. The nuclear area (NA), nuclear length (NL), total AgNORs area (TAA), total AgNORs length (TAL) and total AgNORs number (TAN) of 100 analyzable nuclei of lymphocytes from each tissue were recorded. In spite of a decline in the average NA and NL of thymocytes from garlic-treated rats (p<0.001), TAA and TAL increased significantly (p<0.001) in the splenocytes and thymocytes of this group. In conclusion, garlic may enhance the lymphocyte proliferation in these two important organs from the rat immune system.

Stimulatory effect on rat thymocytes proliferation and antimicrobial activity of two 6-(propan-2-yl)-4-methyl-morpholine-2,5-diones

Recently we reported the identification and synthesis of cyclodidepsipeptides, 3,6-di(propan-2-yl)-4-methyl-morpholine-2,5-dione (PPM) and 3-(2-methylpropyl)-6-(propan-2-yl)-4-methyl-morpholine-2,5-dione (BPM), as potential precursors of enniatin B in Fusarium sporotrichioides. No data concerning biological activity of PPM and BPM have hitherto been published. The possible immunomodulatory effect and antimicrobial activity of PPM and BPM were investigated in this study, due to well known biological activities of enniatin B. The cytotoxicity effect of PPM and BPM on rat thymocytes demonstrated that increasing concentrations (0.1, 1, 10μg/well) of PPM and BPM to cell culture, showed no significant effect on thymocytes toxicity. Simultaneously, incubation with studied cyclodidepsipeptides did not result with decreased mitochondrial membrane potential. Further, thymocytes exposure to increasing concentration of PPM and BPM was not able to induce significant reactive oxygen species (ROS) production in rat thymocytes. PPM and BPM administrations to cell culture in concentrations of 0.1 and 1μg/well resulted with no significant increase of proliferative activity. However, significantly increased proliferative activity was detected with 10μg of PPM (p<0.001) and BPM (p<0.05), as compared to their respective controls. The in vitro antimicrobial activity of PPM and BPM was tested against two Gram-positive and three Gram-negative bacteria. The results indicated that MIC values against tested strains ranged between 2.00 and 25.00mg/ml. PPM showed much better activity against all tested bacteria in comparison with BPM. PPM was equally effective against both Gram-positive and Gram-negative bacteria, at the dose of 2.00mg/ml.

Triclosan, an antibacterial agent, increases intracellular Zn2+ concentration in rat thymocytes: Its relation to oxidative stress

Triclosan is used as an antibacterial agent in household items and personal care products. Since this compound is found in maternal milk of humans and bodies of wild animals, there is growing concern among some consumer groups and scientific community that triclosan is adverse for humans and wild animals. In order to estimate adverse actions of triclosan, the effects of triclosan on intracellular Zn2+ concentration and cellular thiol content were studied in rat thymocytes by the use of flow cytometer with appropriate fluorescent probes. Triclosan at 1–3μM (sublethal concentrations) increased the intensity of FluoZin-3 fluorescence (intracellular Zn2+ concentration) and decreased the intensity of 5-chloromethylfluorescein (5-CMF) fluorescence (cellular thiol content). Negative correlation (r=−0.985) between triclosan-induced changes in FluoZin-3 and 5-CMF fluorescences was found. Removal of external Zn2+ did not significantly affect the triclosan-induced augmentation of FluoZin-3 fluorescence, suggesting an intracellular Zn2+ release by triclosan. These actions of triclosan were similar to those of H2O2 and triclosan significantly potentiated the cytotoxicity of H2O2. Therefore, the results may suggest that triclosan at sublethal concentrations induces oxidative stress that decreases cellular thiol content, resulting in an increase in intracellular Zn2+ concentration by Zn2+ release from intracellular store(s). Since recent studies show many physiological roles of intracellular Zn2+ in cellular functions, the triclosan-induced disturbance of cellular Zn2+ homeostasis may induce adverse actions on the cells.

MORPHOMETRIC CHARACTERISTIC OF THYMOCYTES IN RATS WITH DIABETES MELLITUS, COMPLICATED BY ISCHEMIA-REPERFUSION BRAIN DAMAGE

The influence of brain ischemia-reperfusion on the morphometric characteristics of thymocytes in rats with diabetes mellitus has been investigated. It has been shown that according to the degree of changes of morphometric parameters diabetes most significantly modifies the response of small thymocytes to ischemia-reperfusion of the brain in the cortical zone of the thymus and lymphoblasts and small thymocytes – in the medullary zone.

Triclosan, an environmental pollutant from health care products, evokes charybdotoxin-sensitive hyperpolarization in rat thymocytes

The effects of triclosan, an environmental pollutant from household items and health care products, on membrane potential and intracellular Ca 2+ concentrations of rat thymocytes were examined by a flow cytometry with fluorescent probes, di-BA-C 4 and fluo-3-AM, because triclosan is often found in humans and wild animals. Triclosan at a concentration of 3 μM decreased the intensity of di-BA-C 4 fluorescence, indicating the triclosan-induced hyperpolarization. The application of charybdotoxin, a specific inhibitor of Ca 2+-dependent K + channels, and the removal of external Ca 2+ eliminated the triclosan-attenuation of di-BA-C 4 fluorescence. Furthermore, triclosan augmented the fluo-3 fluorescence under normal Ca 2+ condition, indicating that triclosan increased intracellular Ca 2+ concentration. These results suggest that triclosan induces membrane hyperpolarization by increasing intracellular Ca 2+ concentration that activates Ca 2+-dependent K + channels. Since the change in membrane potential of lymphocytes influence cellular immune functions, triclosan may exert adverse actions on immune system in human and wild animals.

Putative role of intracellular Zn2+ release during oxidative stress: a trigger to restore cellular thiol content that is decreased by oxidative stress

Although the ability of zinc to retard the oxidative process has been recognized for many years, zinc itself has been reported to induce oxidative stress. In order to give some insights into elucidating the role of intracellular Zn(2+) in cells suffering from oxidative stress, the effects of N-ethylmaleimide (NEM) and ZnCl(2) on cellular thiol content and intracellular Zn(2+) concentration were studied by use of 5-chloromethylfluorescein diacetate (5-CMF-DA) and FluoZin-3 pentaacetoxymethyl ester (FluoZin-3-AM) in rat thymocytes. The treatment of cells with NEM attenuated 5-CMF fluorescence and augmented FluoZin-3 fluorescence in a dose-dependent manner. These NEM-induced phenomena were observed under external Zn(2+)-free conditions. Results suggest that NEM decreases cellular thiol content and induces intracellular Zn(2+) release. Micromolar ZnCl(2) dose-dependently augmented both FluoZin-3 and 5-CMF fluorescences, suggesting that the elevation of intracellular Zn(2+) concentration increases cellular thiol content. Taken together, it is hypothesized that intracellular Zn(2+) release during oxidative stress is a trigger to restore cellular thiol content that is decreased by oxidative stress.

Effects of pneumonia caused by klebsiella pneumoniae on apoptosis of thymocytes in rats

Objective To study the effects of pneumonia caused by Klebsiella pneumoniae on apoptosis of thymocytes in rats and its possible mechanism. Methods A total of 48 Sprague Dawley rats were randomly (random number) divided into 2 groups, namely the control group (n =24) and the infection group ( n = 24). The pneumonia models of rats were made with 0.3 mL Klebsiella pneumoniae suspension administered intratracheally per animal. On the 2nd, 4th, and 6th day after intratracheal instillation of bacteria, 1/ 3 of the rats in each group were sacrificed and TdT-mediated dUTP nick end labeling (TUN EL) method was used to assess the apoptosis of thymocytes. The expressions of cleaved Caspase-3, Bcl-2 and Fas in thympcytes of rats were detected with immunohistochemical staining. Results On each interval, apoptosis index of thymocytes, and the expressions of Cleaved Caspase-3 and Fas in the infection group were all higher than those in the control group (P < 0.01) , while the expressions of Bcl-2 lower than those in the control group (P<0.01). As more time consumed, the apoptotic index of thymocytes and the expressions of cleaved Caspase-3 in the infection group increased significantly (P<0.05). The expressions of Bcl-2 declined gradually (P < 0.05), but the expressions of Fas reached their peak 4th day after infection. There were no significant dynamic changes in all above mentioned variables in control group. Conclusions Pneumonia caused by Klebsiella Pneumoniae can lead to the increase in thymocyte apoptosis in rats. The mechanism may be associated with the decreased expression of Bcl-2 and the increased expression of Fas in thymocytes of rats with pneumonia caused by Klebsiella pneumoniae. The different apoptosis regulation pathways have different effects on different phase of pneumonia, that the effects of Fas decrease 4th day after pneumonia, while the effects of Bcl-2 increase further. Key words: Klebsiella pneumoniae; Pneumonia; Thymocyte; Rat; Apoptosis; Cleaved Caspase-3; Bcl-2; Fas

Exposure of Jurkat cells to bis (tri-n-butyltin) oxide (TBTO) induces transcriptomics changes indicative for ER- and oxidative stress, T cell activation and apoptosis

Tributyltin oxide (TBTO) is an organotin compound that is widely used as a biocide in agriculture and as an antifouling agent in paints. TBTO is toxic for many cell types, particularly immune cells. The present study aimed to identify the effects of TBTO on the human T lymphocyte cell line Jurkat. Cells were treated with 0.2 and 0.5 μM TBTO for 3, 6, 12 and 24 h and then subjected to whole genome gene expression microarray analysis. The biological interpretation of the gene expression profiles revealed that endoplasmic reticulum (ER) stress is among the earliest effects of TBTO. Simultaneously or shortly thereafter, oxidative stress, activation of NFKB and NFAT, T cell activation, and apoptosis are induced. The effects of TBTO on genes involved in ER stress, NFAT pathway, T cell activation and apoptosis were confirmed by qRT-PCR. Activation and nuclear translocation of NFATC1 and the oxidative stress response proteins NRF2 and KEAP1 were confirmed by immunocytology. Taking advantage of previously published microarray data, we demonstrated that the induction of ER stress, oxidative stress, T cell activation and apoptosis by TBTO is not unique for Jurkat cells but does also occur in mouse thymocytes both ex vivo and in vivo and rat thymocytes ex vivo. We propose that the induction of ER stress leading to a T cell activation response is a major factor in the higher sensitivity of immune cells above other types of cells for TBTO.

C-Phycocyanin: An effective protective agent against thymic atrophy by tributyltin

Spirulina platensis, used worldwide as a food supplement, is a natural source of protein, vitamins, carbohydrates and polyunsaturated fatty acids. C-Phycocyanin (C-Pc), its major biliprotein, is known to possess anti-oxidant, anti-inflammatory and radical scavenging properties. Our present study showed that treatment with C-Pc protects the rats from Tributyltin (TBT) induced thymic atrophy. The results reveal TBT-induced oxidative stress mediated apoptosis in rat thymocytes in vivo and its attenuation by C-Pc. This ameliorative effect could be attributed to antioxidant activity of the biliprotein. C-Pc also increased TBTC reduced thymic weight and cellularity as well. TBTC-induced ROS generation and lowered GSH levels were restored by C-Pc, suggesting its radical scavenging properties. The various apoptotic determinants such as mitochondrial membrane potential, Bax/Bcl-2 ratio, caspase-3 activity and apoptotic cell population were effectively modulated by C-Pc treatment. We make this first observation to illustrate the effectiveness of C-Pc in reducing TBTC-induced thymic atrophy. The morphology of thymic tissue was restored to near normal by this biliprotein. The present study, therefore, suggests that C-Pc could serve as an effective natural antioxidant for efficient management of TBTC induced oxidative damage.

Some characteristics of membrane Cd2+ transport in rat thymocytes: an analysis using Fluo-3

Although cadmium-induced apoptosis of lymphocytes is one of common features in the immunotoxicity of cadmium, the membrane pathway for intracellular cadmium accumulation is not fully elucidated. To characterize membrane Cd(2+) transport of rat thymocytes, the change in intracellular Cd(2+) concentration under various conditions was examined by the use of Fluo-3, a fluorescent probe for monitoring the change in intracellular concentration of divalent metal cations. The membrane Cd(2+) transport was estimated by the augmentation of Fluo-3 fluorescence induced by bath application of CdCl(2). Lowering temperature strongly suppressed the augmentation of Fluo-3 fluorescence by CdCl(2), suggesting that the metabolic process can be involved in membrane Cd(2+) transport. External acidification (decreasing pH) and membrane depolarization by adding KCl attenuated the augmentation, indicating the requirement of electrochemical driving force for membrane Cd(2+) transport into the cells. Bath application of CaCl(2) and ZnCl(2) equally decreased the augmentation, suggesting their competition with Cd(2+) at the membrane transport. The augmentation by CdCl(2) was lesser in the cells treated with N-ethylmaleimide inducing chemical depletion of cellular thiols. The result suggests the contribution of sulfhydryl groups to membrane Cd(2+) transport. Taken together, it is suggested that the cells possess a temperature-sensitive membrane Cd(2+) pathway, driven by electrochemical gradient of Cd(2+) and transmembrane potential, with competitive binding site. Based on the characteristics described above, it is unlikely that the membrane Cd(2+) transport in rat thymocytes is attributed to a single transport system although it has characteristics that are similar to those of divalent cation transporter 1.

Cytometric analysis on cytotoxicity of curcumin on rat thymocytes: Proapoptotic and antiapoptotic actions of curcumin

Curcumin exhibits various pharmacological actions including anti-inflammatory, anti-infectious, and anticancer actions. Furthermore, the supplements containing curcumin are supplied for persons consuming alcoholic beverage. A primary criterion for an ingredient ingested by general population is that it exerts no harmful effect. In this study, we examined the effect of curcumin on rat thymocytes to see if curcumin exerts cytotoxicity on normal cells. The incubation with 10 μM curcumin for 24 h increased the population of dead cells while it was not the case for 5 μM or less. Curcumin at 5–10 μM increased the populations of shrunken cells and the cells positive to annexin V, phenomena for early stage of apoptosis. However, the incubation with 10 μM curcumin suppressed the increase in population of cells with hypodiploid DNA, a phenomenon for late stage of apoptosis. Thus, curcumin at 10 μM may show both proapoptotic and antiapoptotic actions. The simultaneous incubation with 5 μM, but not 3 μM, curcumin and 0.5% ethanol increased the population of shrunken cells. It is likely that curcumin at 5 μM or more exerts cytotoxic action on normal cells although many studies show some anticancer actions of curcumin at 10 μM or more on cancer cells.

Molecular-biological problems of drug design and mechanism of drug action

The cytotoxicities of capecitabine (Lab Tutour, Argentina) and xeloda (Roche) have been compared with respect to MCF-7 (human breast cancer cell line), HT-12 (colon cancer), and rat thymocytes by the MTT test. The cytotoxic activities of both drugs were the same and were highly selective with respect to the tumor cells. The sensitivity of the cells to the cytostatics increased in the order thymocytes < HT-12 < MCF-7.

Cytotoxic Characteristics of Two Isomeric Dimers Produced by Oxidation of Sesamol, an Antioxidant in Sesame Oil

Antioxidants themselves are oxidized to prevent oxidation of other molecules. One may ask if the oxidized antioxidants are safe for humans. However, there is very little information on the toxicity of oxidized antioxidants. We previously identified cytotoxic compounds in the products from oxidation of sesamol, a potent antioxidant in sesame oil. In this study using a flow cytometer with fluorescent probes, we revealed cytotoxic characteristics of two isomeric dimers (dimer A and B) in rat thymocytes. Increase in cell lethality by dimer A was more profound than those by sesamol and dimer B. The incubation of cells with dimer A increased the populations of shrunken cells and the cells with phosphatidylserine exposed on outer surface of cell membranes. Since these phenomena are parameters for early stage of apoptosis, the results indicate that dimer A may promote the process of apoptosis. However, the population of the cells containing hypodiploid DNA, a parameter for late stage of apoptosis, was decreased by the incubation with dimer A. It was not the case for dimer B. Results indicate that dimer A may inhibit the degradation of DNA during apoptosis. Taken together, it is likely that dimer A exerts both proapoptotic action and inhibitory action on late stage of apoptosis in rat thymocytes.

Oleic Acid Versus Linoleic and α-Linolenic Acid. Different Effects on Ca2+ Signaling in Rat Thymocytes

Background: Oleic acid is the principal fatty acid of olive oil composition and is reported to play a crucial role in its healthy aspects. However, the detailed mechanism of action is poorly understood. Aims: This study aims to elucidate the role of oleic acid in calcium signaling in rat thymocytes, in comparison to linoleic and linolenic acid. Methods: Fatty acids were applied to thymocytes isolated from wistar rats and loaded with Fura-2 to measure calcium signals. Results: The main results showed a concentration-dependent increase in [Ca²⁺]_i induced by the 3 fatty acids. Raising the number of unsaturations resulted in greater increases. Two different pathways contributed to the increase induced by the polyunsaturated fatty acids: an IP₃- independent release from the thapsigargin-sensitive stores and an extracellular calcium entry by econazole and nifedipine-insensitive channels. However, the OA-induced increases in [Ca²⁺]_i seemed to be due mostly to the Ca²⁺ recruited from the intracellular stores. Conclusion: This study demonstrates that the fatty acids tested induce increases in [Ca²⁺]_i in rat thymocytes, with differences in close relation to the degree of unsaturation. Such differences could be responsible for their different physiological action.