Proline Treatment Research Articles

Effects of chronic proline administration on lipid contents of rat brain

In the present work we investigated the effects of chronic proline administration on ganglioside, cholesterol and phospholipid total contents, as well as on ganglioside profile in cerebral cortex, hippocampus, hypothalamus and cerebellum of rats. We also evaluated the ganglioside content and profile in detergent-soluble and resistant microdomains isolated from synaptic membranes obtained from cerebral cortex. Proline solution (hyperprolinemic) or saline (control) were subcutaneously administered to rats from 6th to 28th post-natal day, according to body weight. Twelve hours after the last injection, the animals were sacrificed by decapitation without anaesthesia. Brain structures were homogenized with chloroform:methanol for lipid extraction. Synaptic membranes were obtained by differential centrifugation and detergent-soluble and resistant microdomains were isolated by cold Triton X-100 treatment. Results showed that rats subjected to chronic proline treatment presented a significant increase of ganglioside content in cortex and hippocampus, while this membrane lipid content was not altered in hypothalamus and cerebellum. Besides, phospholipid and cholesterol contents were not modified in all structures studied. On the other hand, ganglioside content decreased in detergent-soluble and resistant microdomains isolated from synaptic membrane obtained from hyperprolinemic cortex. Although ganglioside profiles were apparently not modified, the individual absolute quantities were altered in cortex and hippocampus total lipid extract and membrane microdomains. Our findings suggest that chronic proline treatment affects in a distinct manner different cerebral regions concerning the lipid composition of the cell membranes, reflecting on its distribution in the cortex membrane microdomains. Among these phenomena consequences, distinct modulations in synaptic transmission may be suggested which might contribute to the impairment in cognition and/or other neurological dysfunctions found in hyperprolinemia type II patients.

Maize and soybean seed vigour under influence of seed age, seed treatment and temperature in cold stress test

Maize and soybean seed (maize hybrid OS 499 and soybean cultivar Ika originated from Agricultural Institute in Osijek, Croatia) harvested in year 2006 as well as one year old seed (harvested in 2005 and aged in storehouse conditions) were used for the evaluation of seed vigour in germination chamber. Seeds were pretreated with fungicide. Fungicide treatment significantly increased germination rate of maize seed in cold test conditions and constant low temperature. Fungicide treatment of soybean seed significantly enhanced germination only at constant low temperature and aged seed. Biostimulant applicaton did not enhanced germination rate but increased dry matter content in normally developed hypocotyls, both in fresh and aged soybean seed. Proline treatment did not show expected stimulative effect on seed germination.

Improved salt tolerance of melon ( Cucumis melo L.) by the addition of proline and potassium nitrate

A pot experiment was carried out under glasshouse conditions with melon ( Cucumis melo) cv. “Tempo F1” in a mixture of peat, perlite and sand (1:1:1) to investigate the effects of external proline and potassium nitrate applications to salinity-treated (150 mM) plants with respect to fruit yield, plant growth, some physiological parameters and ion uptake. Treatments were—(i) control (C): plants receiving nutrient solution, (ii) salinity treatment, as for control plus 150 mM NaCl. Salinity treatment was combined with or without either 5 mM supplementary KNO 3 or 10 mM proline. The salt treatment (150 mM NaCl) led to significant decreases in plant growth, fruit yield, relative water content (RWC), stomatal density, uptake of Ca 2+, K + and N, and chlorophyll a and b contents, accompanied by significant increases in Na + uptake, proline concentration and membrane permeability. Supplementary KNO 3 and proline treatments significantly ameliorated the adverse effects of salinity on plant growth, fruit yield and the physiological parameters examined. This could be attributed to the effects of all the external supplements in maintaining membrane permeability, and increasing concentrations of Ca 2+, N and K + in the leaves of plants subjected to salt stress.

Influence of Proline on Rat Brain Activities of Alanine Aminotransferase, Aspartate Aminotransferase and Acid Phosphatase

Hyperprolinemia type II (HPII) is an autosomal recessive disorder caused by the severe deficiency of enzyme delta1-pyrroline-5-carboxylic acid dehydrogenase leading to tissue accumulation of proline. Chronic administration of Pro led to significant reduction of cytosolic ALT activity of olfactory lobes (50.57%), cerebrum (40%) and medulla oblongata (13.71%) only. Whereas mitochondrial ALT activity was reduced significantly in, all brain regions such as olfactory lobes (73.23%), cerebrum (70.26%), cerebellum (65.39%) and medulla oblongata (65.18%). The effect of chronic Pro administration on cytosolic AST activity was also determined. The cytosolic AST activity from olfactory lobes, cerebrum and medulla oblongata reduced by 75.71, 67.53 and 76.13%, respectively while cytosolic AST activity from cerebellum increased by 28.05%. The mitochondrial AST activity lowered in olfactory lobes (by 72.45%), cerebrum (by 78%), cerebellum (by 49.56%) and medulla oblongata (by 69.30%). In vitro studies also showed increase in brain tissue proline and decrease in glutamate levels. In vitro studies indicated that proline has direct inhibitory effect on these enzymes and glutamate levels in brain tissue showed positive correlation with AST and ALT activities. Acid phosphatase (ACP) activity reduced significantly in olfactory lobes (40.33%) and cerebrum (20.82%) whereas it elevated in cerebellum (97.32%) and medulla oblongata (76.33%). The histological studies showed degenerative changes in brain. Following proline treatment, the animals became sluggish and showed low responses to tail pricks and lifting by tails and showed impaired balancing. These observations indicate influence of proline on AST, ALT and ACP activities of different brain regions leading to lesser synthesis of glutamate thereby causing neurological dysfunctions.

Note: Proline — An inducer of resistance against pearl millet downy mildew disease caused bySclerospora graminicola

In an attempt to find a suitable alternative to the otherwise perilous chemical control strategy of disease management, the amino acid proline was evaluated for its efficiency to elicit resistance in pearl millet (Pennisetum glaucum (L.) R. Br.) against downy mildew disease caused by Sclerospora graminicola (Sacc.) Schroet both under greenhouse and field conditions. Proline treatment to seeds at 50 mM concentration for 3 h, significantly enhanced the seed germination and seedling vigor of pearl millet in comparison with the control. The same concentration and duration of seed treatment protected the pearl millet plants from downy mildew by offering 58% protection under greenhouse and 67% protection under field conditions. Studies revealed that 3 days were required for proline-treated plants to develop resistance, which was systemic and was sustained throughout the life of the plants. Apart from disease protection, proline was also found effective in enhancing vegetative and reproductive growth of the plants, as evidenced by the increase in height, fresh weight, leaf area, tillering capacity, 1000-seed weight and grain yield in comparison with the control plants.

Response of Barley Seedlings to UV-B Radiation as Affected by Proline and NaCl

Barley (Hordeum vulgare L. cv. Alfa) seedlings were treated for 4 d before UV-B irradiation with 0.05 mM proline or 150 mM NaCl. UV-B exposure induced synthesis of yellow coloured compounds with maximum absorbance at 438 nm. The content of these compounds was increased in proline-treated and decreased in NaCl-treated plants. UV-B radiation reduced chlorophyll/carotenoids ratio, oxygen evolution rate and photochemical efficiency of PS 2 as estimated by chlorophyll fluorescence and increased proline accumulation, H2O2 generation and lipid peroxidation. Exogenous proline had no effect on the parameters studied and did not change the response of plants to UV-B radiation. NaCl inhibited photochemical efficiency of PS 2, reduced oxygen evolution and increased H2O2 concentration and lipid peroxidation. The combination of NaCl and proline treatment led to lowering the inhibitory effect of NaCl in non UV-B irradiated seedlings. There was not relationship between the level of UV-B-induced compounds and UV-B tolerance of barley seedlings.

Stimulation of total phenolics, L-DOPA and antioxidant activity through proline-linked pentose phosphate pathway in response to proline and its analogue in germinating fava beans ( Vicia faba)

The rationale behind the study was to enhance azetedine-2-carboxylate (A2C)-linked stress in the germinating seeds to which it responds by increased proline synthesis to overcome inhibition of proline dehydrogenase (PDH). A2C is a competitive inhibitor of proline that inhibits its transport from cytosol to the mitochondria for further metabolic recycling by binding on to the active sites of PDH. The enhanced synthesis of proline would increase the ratio of the cofactors NADP/NADPH 2. The increase in the cofactors would result in the over-expression of the phenypropanoid pathway required for the phenolic acids and L-DOPA synthesis via pentose phosphate pathway through the activity of glucose-6-phosphate dehydrogenase (G6PDH). Fava bean were chosen since it has high phenolic and L-DOPA levels and could be an important part of the diet especially for patients suffering from Parkinson's Disease. The objectives were investigated by assaying for total phenolic content, the corresponding antioxidant activity by β-carotene oxidation method, proline levels and enzymes such as G6PDH and guaiacol peroxidase (GPX) using spectrophotometric methods. L-DOPA was quantified using HPLC. The fava bean seeds were primed with water, 200 μM A2C, 0.25 mM proline and a combination of A2C and proline treatments. After the priming stage, seeds were dark germinated and grown for a period of 8 days, for biochemical analysis. L-DOPA levels did not change in comparison to the control treatments while total phenolic content, proline and G6PDH were all enhanced by the treatments. During the early stages of germination the phenolic acids were antioxidant in nature, which later was reduced as they become polymerized to lignins and lignans via the GPX activity. Total phenolic synthesis was both coupled and uncoupled to PLPPP depending on the treatments. The three treatments over-expressed PLPPP since large difference between control and the treatments were observed for all parameters, except L-DOPA content.

Cell wall peroxidase activity, hydrogen peroxide level and NaCl-inhibited root growth of rice seedlings

The changes in cell-wall peroxidase (POD) activity and H2O2 level in roots of NaCl-stressed rice seedlings and their correlation with root growth were investigated. Increasing concentrations of NaCl from 50 to 150 mM progressively reduced root growth and increased ionically bound cell-wall POD activity. NaCl had no effect on covalently bound cell-wall POD activities. The reduction of root growth by NaCl is closely correlated with the increase in H2O2 level. Exogenous H2O2 was found to inhibit root growth of rice seedlings. Since ammonium and proline accumulation are associated with root growth inhibition caused by NaCl, we determined the effects of NH4Cl or proline on root growth, cell-wall POD activity and H2O2level in roots. External application of NH4Cl or proline markedly inhibited root growth, increased cell-wall POD activity and increased H2O2 level in roots of rice seedlings in the absence of NaCl. An increase in cell-wall POD activity and H2O2 level preceded inhibition of root growth caused by NaCl, NH4Cl or proline. NaCl or proline treatment also increased NADH-POD and diamine oxidase (DAO) activities in roots of rice seedlings, suggesting that NADH-POD and DAO contribute to the H2O2 generation in the cell wall of NaCl- or proline-treated roots. NH4Cl treatment increased NADH-POD activity but had no effect on DAO activity, suggesting that NADH-POD but not DAO is responsible for H2O2 generation in cell wall of NH4Cl-treated roots.

The effect of in planta TIBA and proline treatment on somatic embryogenesis of sugar beet (Beta vulgaris L.).

The effect of in planta TIBA and L-proline onin vitro seedlings and cell culture of sugar beet was investigated. Sterilized seeds were grownin vitro on 1/2 MS medium supplemented with 0 or3 mg/l TIBA. Calli obtained on young leaves cultured on MS medium containing 1 mg/l BAP, were used for the initiation of cell suspension cultures using MS basal composition supplemented with 0 or 50 mM proline. Aliquots of 1 ml from cell suspension culture were inoculated onto the first somatic embryo induction MS medium containing TIBA 0.5 mg/l, BAP 1.0 mg/l, and proline at 0 or 50 mM. After three weeks of culture, embryogenic calli were transferred to the second embryo induction medium supplemented with NAA and BAP at 0.2 and 0.5 mg/l, respectively. The frequency of somatic embryos of calli obtained from in plantaTIBA together with proline treatments on average was20 which was higher than that of the other treatments.

Alpha-methyl-proline restores normal levels of bone collagen type i synthesis in ovariectomized rats

Collagen type I is the major protein of bone matrix and significantly reduced in osteoporosis. We tested the effect of alpha — methyl — proline on collagen synthesis in the model of the ovariectomized rat. Collagen synthesis was studied at the transcriptional level using Northern and dot blotting and at the protein level using hydroxyproline determination and a specific dye binding collagen assay. Alpha — methyl — proline treatment significantly increased collagen synthesis as compared to untreated ovariectomized and estradiol treated ovariectomized rats and restored collagen synthesis to levels of sham operated rats. Proline analogues were described to stimulate procollagen synthesis at the transcriptional level, however, if incorporated, lead to negative collagen production due to rapid intracellular degradation of the deficient collagen. Our synthesized analogue is not being incorporated, thus not interfering with collagen conformation and can therefore induce collagen production.

Cd induced changes in proline level and peroxidase activity in roots of rice seedlings

The effects of Cd on changes in proline level and peroxidase activity in roots of rice seedlings were investigated. CdCl2 was effective in inhibiting root growth and in accumulating proline in roots. The inhibition of root growth by Cd is reversible. The reduction of root growth induced by Cd is closely associated with accumulation of proline in roots. External application of proline markedly inhibited root growth of rice seedlings in the absence of Cd. Ionically bound, but not soluble, peroxidase activity in roots was increased by CdCl2. Proline treatment also resulted in an increase in ionically bound peroxidase activity in roots. The relationship between growth inhibition of roots induced by Cd and changes of proline level and peroxidase activity is discussed.

Lack of promoting effect of proline on bile duct cancer development in dimethylnitrosamine‐initiated hamster livers

Bile duct hyperplasia caused by proline is believed to represent a chemical effect of the liver fluke, Fasciola hepatica, and the resultant cell division might be expected to play a role as a tumor promoter. To investigate the potential promoting effect of proline on bile duct cancer development, Syrian hamsters were therefore divided into 8 treatment groups: dimethylnitrosamine (DMN) + proline intraperitoneally (i.p.); DMN + proline s.c.; DMN + saline i.p.; DMN + saline s.c.; proline i.p.; proline s.c.; saline i.p.; and saline s.c. DMN was injected i.p. at 20 mg/kg to the animals 2 weeks prior to commencement of proline treatment, whereby 1 ml of a 2 M solution was given by i.p. or s.c. injection 3 times a week for 20 weeks. At the end of week 42, assessment of preneoplastic lesion development did not reveal any significant modulating influence of proline on DMN-initiated lesion development nor did it itself cause persistent bile duct hyperplasia.

Proline Is Not the Primary Determinant of Chilling Tolerance Induced by Mannitol or Abscisic Acid in Regenerable Maize Callus Cultures

Chilling sensitive regenerable maize (Zea mays L.) callus cultures can be induced to survive prolonged exposure to 4 degrees C by treatments with mannitol, abscisic acid (ABA), and/or high levels of proline. Maize callus with a free proline content of about 122 micromoles/grain fresh weight survived longer exposures to 4 degrees C than did callus with a free proline content of about 68 micromoles/grain fresh weight. The addition of 0.53 molar mannitol or 0.1 millimolar ABA to culture medium produced a free proline content in maize callus of about 136 and 145 micromoles/grain fresh weight, respectively, if the medium contained 12 millimolar proline or about 36 and 1 micromoles/grain fresh weight, respectively, if no proline was in the medium. Although these mannitol and ABA treatments produced drastically different free proline levels in maize callus, callus grown on these media survived longer exposures to 4 degrees C than did maize callus grown on any proline treatment alone. Thus, the internal free proline level of treated callus is not the primary factor conferring chilling tolerance on these tissues.

Effect of proline administration on rat behavior in aversive and nonaversive tasks

Sustained levels of proline comparable to those of human type II hyperprolinemia were achieved in blood and brain of rats by subcutaneous proline administration twice a day from the 6th till the 28th day of life. Control rats were treated with saline in the same volumes. Behavioral studies using aversive and nonaversive tasks were performed one week or one month after treatment. Proline treatment did not affect rats' performance in the inhibitory avoidance task, but reduced significantly habituation in the open field. Our results seem to indicate that early postnatal administration of proline to rats affects habituation to a novel environment. If this happens to be so the present tendency to consider hyperprolinemia as a benign condition should be revised.

Protection of pollen germination from adverse temperatures: a possible role for proline

Abstract After germination, pollen grains of Lilium longiflorum became very sensitive to short periods of heat stress as shown by the greatly reduced germination percentages upon subsequent incubation at the optimal temperature. Addition of proline to the incubation medium made pollen more resistant to heat. It was demonstrated that in a short time a large amount of proline was taken up by the cell. Germination and metabolic functions were completely or partially protected from heat damage by proline treatment. As well, it was shown that proline treatment at least partially protected pollen grains from cold stress. These results suggest that the high proline concentrations found in pollen of many species may confer resistance to germinating pollen grains at unfavourable temperatures thereby enhancing the chances of successful fertilization.

Survival of Solanum tuberosum suspension cultures to –14°C: The mode of action of proline

Normally suspension cultures of potato, Solanum tuberosum, can survive only to a freezing temperature of –2°C. The treated cultures were able to survive at much lower freezing temperature after the addition of l‐proline of 0.43 M or more to the suspension medium and treatment for 1.5 h. Cultures could survive to ‐14°C with 0.87 M proline treatment. Treatments with higher concentration than 0.87 M resulted in no additional freezing survival. Microscopical observations of the treated cultures before freezing showed that proline induced plasmolysis, which was initiated at the 0.43 M level and reached maximum at 0.87 M. The mode of action of proline, appears to be due to the removal of excessive intracellular water by the osmotic gradient. Sucrose at about the same concentration acted in the same way as proline. The cryoprotective role of proline and sucrose is discussed in relation to the action of the permeant dimethylsulfoxide.