Vitamin E protects against photoinhibition and photooxidative stress in Arabidopsis thaliana

Vitamin E is considered a major antioxidant in biomembranes, but little evidence exists for this function in plants under photooxidative stress. Leaf discs of two vitamin E mutants, a tocopherol cyclase mutant (vte1) and a homogentisate phytyl transferase mutant (vte2), were exposed to high light stress at low temperature, which resulted in bleaching and lipid photodestruction. However, this was not observed in whole plants exposed to long-term high light stress, unless the stress conditions were extreme (very low temperature and very high light), suggesting compensatory mechanisms for vitamin E deficiency under physiological conditions. We identified two such mechanisms: nonphotochemical energy dissipation (NPQ) in photosystem II (PSII) and synthesis of zeaxanthin. Inhibition of NPQ in the double mutant vte1 npq4 led to a marked photoinhibition of PSII, suggesting protection of PSII by tocopherols. vte1 plants accumulated more zeaxanthin in high light than the wild type, and inhibiting zeaxanthin synthesis in the vte1 npq1 double mutant resulted in PSII photoinhibition accompanied by extensive oxidation of lipids and pigments. The single mutants npq1, npq4, vte2, and vte1 showed little sensitivity to the stress treatments. We conclude that, in cooperation with the xanthophyll cycle, vitamin E fulfills at least two different functions in chloroplasts at the two major sites of singlet oxygen production: preserving PSII from photoinactivation and protecting membrane lipids from photooxidation.

Plant glutathione peroxidases are functional peroxiredoxins distributed in several subcellular compartments and regulated during biotic and abiotic stresses

We provide here an exhaustive overview of the glutathione (GSH) peroxidase (Gpx) family of poplar (Populus trichocarpa). Although these proteins were initially defined as GSH dependent, in fact they use only reduced thioredoxin (Trx) for their regeneration and do not react with GSH or glutaredoxin, constituting a fifth class of peroxiredoxins. The two chloroplastic Gpxs display a marked selectivity toward their electron donors, being exclusively specific for Trxs of the y type for their reduction. In contrast, poplar Gpxs are much less specific with regard to their electron-accepting substrates, reducing hydrogen peroxide and more complex hydroperoxides equally well. Site-directed mutagenesis indicates that the catalytic mechanism and the Trx-mediated recycling process involve only two (cysteine [Cys]-107 and Cys-155) of the three conserved Cys, which form a disulfide bridge with an oxidation-redox midpoint potential of -295 mV. The reduction/formation of this disulfide is detected both by a shift on sodium dodecyl sulfate-polyacrylamide gel electrophoresis or by measuring the intrinsic tryptophan fluorescence of the protein. The six genes identified coding for Gpxs are expressed in various poplar organs, and two of them are localized in the chloroplast, with one colocalizing in mitochondria, suggesting a broad distribution of Gpxs in plant cells. The abundance of some Gpxs is modified in plants subjected to environmental constraints, generally increasing during fungal infection, water deficit, and metal stress, and decreasing during photooxidative stress, showing that Gpx proteins are involved in the response to both biotic and abiotic stress conditions.

Plant thioredoxins are key actors in the oxidative stress response

Thioredoxins are ubiquitous disulfide reductases that regulate the redox status of target proteins. Although plant thioredoxins display a striking diversity not found in other organisms, many of their physiological roles have yet to be determined. Based on recent publications investigating thioredoxin targets and genetically modified plants, thioredoxins appear to play a fundamental role in plant tolerance of oxidative stress. They are involved in oxidative damage avoidance by supplying reducing power to reductases detoxifying lipid hydroperoxides or repairing oxidized proteins. Furthermore, other lines of evidence indicate that thioredoxins could act as regulators of scavenging mechanisms and as components of signalling pathways in the plant antioxidant network.

Nipple sparing mastectomy with nipple areola intraoperative radiotherapy: one thousand and one cases of a five years experience at the European institute of oncology of Milan (EIO)

In order to reduce mutilation, nipple-areola complex (NAC) conservation can be proposed for the treatment of breast cancer when mastectomy is indicated. To reduce the risk of retro areolar recurrence, a novel radiosurgical treatment combining subcutaneous mastectomy with intraoperative radiotherapy (ELIOT) is proposed. One thousand and one nipple sparing mastectomies (NSM) were performed from March 2002 to November 2007 at the European institute of oncology (EIO), for invasive carcinoma in 82% of the patients and in situ carcinoma in 18%. Clinical complications, aesthetic results, oncological and psychological results were recorded. A comparison was performed between the 800 patients who received ELIOT and the 201 who underwent delayed one-shot radiotherapy on the days following the operation. The median follow up time was 20 months (range 1-69) for a follow up performed in 83% of the patients. The NAC necrosed totally in 35 cases (3.5%) and partially in 55 (5.5%) and was removed in 50 (5%). Twenty infections (2%) were observed and 43 (4.3%) prostheses removed. The median rate of the patients for global cosmetic result on a scale ranging from 0 (worst) to 10 (excellent) was 8. Evaluation by the surgeon in charge of the follow-up gave a similar result. Only 15% of the patients reported a partial sensitivity of the NAC. Of the fourteen (1.4%) local recurrences, ten occurred close to the tumour site, all far from the NAC corresponding to the field of radiation. No recurrences were observed in the NAC. In a group of patients characterized by a very close free margin under the areola, no local recurrence was observed. Overall, 36 cases of metastases and 4 deaths were observed. No significant outcome difference was observed between the 800 patients receiving intraoperative radiotherapy (ELIOT) and the 201 patients receiving delayed irradiation.

Brain angiotensin enhances dopaminergic cell death via microglial activation and NADPH-derived ROS

Angiotensin II (AII) plays a major role in the progression of inflammation and NADPH-derived oxidative stress (OS) in several tissues. The brain possesses a local angiotensin system, and OS and inflammation are key factors in the progression of Parkinson's disease. In rat mesencephalic cultures, AII increased 6-OHDA-induced dopaminergic (DA) cell death, generation of superoxide in DA neurons and microglial cells, the expression of NADPH-oxidase mRNA, and the number of reactive microglial cells. These effects were blocked by AII type-1 (AT1) antagonists, NADPH inhibitors, or elimination of glial cells. DA degeneration increased angiotensin converting enzyme activity and AII levels. In rats, 6-OHDA-induced dopaminergic cell loss and microglial activation were reduced by treatment with AT1 antagonists. The present data suggest that AII, via AT1 receptors, increases the dopaminergic degeneration process by amplifying the inflammatory response and intraneuronal levels of OS, and that glial cells play a major role in this process.

Evaluation of fat grafting safety in patients with intraepithelial neoplasia: a matched-cohort study

BACKGROUND

Fat grafting is widely carried out in breast cancer patients to improve quality in breast reconstruction. Recently, in vitro and animal studies have questioned the role of adipose tissues in cancer development.

DESIGNS

Matched-cohort study. We analysed: (i) 59 intraepithelial neoplasia patients who had undergone lipofilling, with no recurrence between primary surgery and lipofilling. (ii) A control group of 118 matched patients (two controls per lipofilling patient) with the corresponding recurrence-free intervals. Both groups were also matched for main cancer criteria. A local event (LE) was the primary end point, with follow-up starting from the baseline.

RESULTS

Median follow-up was 63 and 66 months from surgery, and 38 and 42 from baseline, for the lipofilling and control groups, respectively; the 5-year cumulative incidence of LE was 18% and 3% (P = 0.02). Ki-67 was the significant factor in univariate survival analysis. A subgroup analysis showed that lipofilling increased the risk of LE in women <50 years, with high grade neoplasia, Ki-67 ≥ 14 or who had undergone quadrantectomy.

CONCLUSION

Higher risk of LE was observed in intraepithelial neoplasia patients following lipofilling. Although further studies are required to validate our conclusions, patients belonging to this subgroup should be informed of these results and the potential risks.

Nipple-sparing mastectomy: risk of nipple-areolar recurrences in a series of 579 cases

BACKGROUND

When the conservative treatment is not recommended, Nipple Sparing Mastectomy (NSM) is proposed more and more frequently for the surgical treatment of breast cancer. The risk of local recurrence behind the nipple areolar complex (NAC) is the main limiting factor of the NSM procedure. To minimize such risk, we proposed in 2002 a intraoperative radiotherapy of the preserved NAC.

PATIENTS AND METHODS

From March 2002 to November 2006, 579 cases (in 570 patients) of NSM were performed for carcinoma. The median follow up time was 19 months (Range: 1-60). The subcutaneous mastectomy was performed through an incision removing a portion of the skin overlying the tumour. An extemporaneous histological examination was performed on the retroareolar glandular tissue. If the histology was positive the patient was not considered eligible. Then an intraoperative radiotherapy with electrons (ELIOT) of 16 Gy in one shot was delivered on the NAC area. An immediate breast reconstruction was done using implants in most cases and in several cases a musculocutaneous flaps, usually in large breast. The number of local recurrences was recorded and the correlation between their occurrence and the clinical and histological criteria were analysed using the Gray test statistical method in a competing framework.

RESULTS

In 516 cases the negative retroareolar frozen section biopsy was confirmed by the final histology, while in 63 cases, the final histology showed foci of carcinoma. Seven out of these 63 cases underwent a secondary NAC removal. In the 56 cases which preserved areolas we did not observe any local recurrence after 19 months follow up. The probability of retro areola positive histology increases with the tumour size. and was not related to the nodal status. The rate of local relapses was 0.9% per year. We didn't find any significant difference in the local relapse rate according to different patient's and tumour's features. Most relapses were located close to the tumour bed but never in the NAC area.

CONCLUSION

Our study confirms that the local recurrence rate in the NSM completed with local radiotherapy on the NAC is not higher than the usual rate observed in the literature and the preservation of the NAC does not increase the risk. The absence of local recurrence in the region where a portion of glandular tissue has been purposely preserved is a good argument in favour of ELIOT.

Regeneration mechanisms of Arabidopsis thaliana methionine sulfoxide reductases B by glutaredoxins and thioredoxins

Methionine oxidation leads to the formation of S- and R-diastereomers of methionine sulfoxide (MetSO), which are reduced back to methionine by methionine sulfoxide reductases (MSRs) A and B, respectively. MSRBs are classified in two groups depending on the conservation of one or two redox-active Cys; 2-Cys MSRBs possess a catalytic Cys-reducing MetSO and a resolving Cys, allowing regeneration by thioredoxins. The second type, 1-Cys MSRBs, possess only the catalytic Cys. The biochemical mechanisms involved in activity regeneration of 1-Cys MSRBs remain largely elusive. In the present work we used recombinant plastidial Arabidopsis thaliana MSRB1 and MSRB2 as models for 1-Cys and 2-Cys MSRBs, respectively, to delineate the Trx- and glutaredoxin-dependent reduction mechanisms. Activity assays carried out using a series of cysteine mutants and various reductants combined with measurements of free thiols under distinct oxidation conditions and mass spectrometry experiments show that the 2-Cys MSRB2 is reduced by Trx through a dithiol-disulfide exchange involving both redox-active Cys of the two partners. Regarding 1-Cys MSRB1, oxidation of the enzyme after substrate reduction leads to the formation of a stable sulfenic acid on the catalytic Cys, which is subsequently glutathionylated. The deglutathionylation of MSRB1 is achieved by both mono- and dithiol glutaredoxins and involves only their N-terminal conserved catalytic Cys. This study proposes a detailed mechanism of the regeneration of 1-Cys MSRB activity by glutaredoxins, which likely constitute physiological reductants for this type of MSR.

Mechanism of 6-hydroxydopamine neurotoxicity: the role of NADPH oxidase and microglial activation in 6-hydroxydopamine-induced degeneration of dopaminergic neurons

Cell death induced by 6-hydroxydopamine (6-OHDA) is thought to be caused by reactive oxygen species (ROS) derived from 6-OHDA autooxidation and by a possible direct effect of 6-OHDA on the mitochondrial respiratory chain. However, the process has not been totally clarified. In rat primary mesencephalic cultures, we observed a significant increase in dopaminergic (DA) cell loss 24 h after administration of 6-OHDA (40 micromol/L) and a significant increase in NADPH subunit expression, microglial activation and superoxide anion/superoxide-derived ROS in DA cells that were decreased by the NADPH inhibitor apocynin. Low doses of 6-OHDA (10 micromol/L) did not induce a significant loss of DA cells or a significant increase in NADPH subunit expression, microglial activation or superoxide-derived ROS. However, treatment with the NADPH complex activator angiotensin II caused a significant increase in all the latter. Forty-eight hours after intrastriatal 6-OHDA injection in rats, there was still no loss of DA neurons although there was an increase in NADPH subunit expression and NADPH oxidase activity. The results suggest that in addition to the autooxidation-derived ROS and the inhibition of the mitochondrial respiratory chain, early microglial activation and NADPH oxidase-derived ROS act synergistically with 6-OHDA and constitute a relevant and early component of the 6-OHDA-induced cell death.

Protein-repairing methionine sulfoxide reductases in photosynthetic organisms: gene organization, reduction mechanisms, and physiological roles

Methionine oxidation to methionine sulfoxide (MetSO) is reversed by two types of methionine sulfoxide reductases (MSRs), A and B, specific to the S- and R-diastereomers of MetSO, respectively. MSR genes are found in most organisms from bacteria to human. In the current review, we first compare the organization of the MSR gene families in photosynthetic organisms from cyanobacteria to higher plants. The analysis reveals that MSRs constitute complex families in higher plants, bryophytes, and algae compared to cyanobacteria and all non-photosynthetic organisms. We also perform a classification, based on gene number and structure, position of redox-active cysteines and predicted sub-cellular localization. The various catalytic mechanisms and potential physiological electron donors involved in the regeneration of MSR activity are then described. Data available from higher plants reveal that MSRs fulfill an essential physiological function during environmental constraints through a role in protein repair and in protection against oxidative damage. Taking into consideration the expression patterns of MSR genes in plants and the known roles of these genes in non-photosynthetic cells, other functions of MSRs are discussed during specific developmental stages and ageing in photosynthetic organisms.

The plastidic 2-cysteine peroxiredoxin is a target for a thioredoxin involved in the protection of the photosynthetic apparatus against oxidative damage

The chloroplastic drought-induced stress protein of 32 kD (CDSP32) is composed of two thioredoxin modules and is induced by environmental and oxidative stress conditions. We investigated whether the plastidic protein BAS1, which is related to eubacterial 2-Cys peroxiredoxin, is a target for CDSP32. Using a CDSP32 active-site mutant, we showed that the BAS1 and CDSP32 proteins form a mixed disulfide complex in vitro. Moreover, affinity chromatography indicated that BAS1 is a major target for CDSP32 in chloroplasts. CDSP32 was able to reduce BAS1 in vitro, and BAS1 displayed CDSP32-dependent peroxidase activity. The function of CDSP32 was investigated in transgenic potato lines without detectable levels of the protein as a result of cosuppression. Under conditions of photooxidative stress induced by incubation with either methyl viologen or t-butyl hydroperoxide or by exposure to low temperature under high light, plants lacking CDSP32 exhibited decreased maximal photosystem II photochemical efficiencies compared with the wild type and transgenic controls. In addition, plants without CDSP32 retained much less chlorophyll than controls under stress, indicating increased damage to photosynthetic membranes. We conclude that CDSP32 is a thioredoxin with a critical role in plastid defense against oxidative damage and that this role is related to its function as a physiological electron donor to the BAS1 peroxiredoxin.

Analysis of the proteins targeted by CDSP32, a plastidic thioredoxin participating in oxidative stress responses

The chloroplastic drought-induced stress protein of 32 kDa (CDSP32) is a thioredoxin induced by environmental stress conditions. To gain insight into the function of CDSP32, we applied two strategies to analyze its targets. First, using affinity chromatography with an immobilized CDSP32 active site mutant, we identified six plastidic targets of CDSP32. Three of them are involved in photosynthetic processes: ATP-ase gamma-subunit, Rubisco and aldolase. The three others participate in the protection against oxidative damage: two peroxiredoxins, PrxQ and the BAS1 2-Cys peroxiredoxin, and a B-type methionine sulfoxide reductase. Then, we developed a novel strategy to trap targets directly in leaf extracts. The method, based on co-immunoprecipitation using extracts from plants overexpressing Wt CDSP32 or CDSP32 active site mutant, confirmed the interaction in vivo between CDSP32 and the PrxQ and BAS1 peroxiredoxins. We showed that CDSP32 is able to form heterodimeric complexes with PrxQ and that the peroxiredoxin displays CDSP32-dependent peroxidase activity. Under photooxidative stress induced by methyl viologen, plants overexpressing CDSP32 active site mutant exhibit decreased maximal PSII photochemical efficiency and retain much less chlorophyll compared with Wt plants and with plants overexpressing Wt CDSP32. We propose that the increased sensitivity results from trapping in planta of the targets involved in the protection against oxidative damage. We conclude that CDSP32, compared with other plant thioredoxins, is a thioredoxin more specifically involved in plastidic responses against oxidative stress.

Plant methionine sulfoxide reductase A and B multigenic families

Methionine oxidation to methionine sulfoxide (MetSo), which results in modification of activity and conformation for many proteins, is reversed by an enzyme present in most organisms and termed as methionine sulfoxide reductase (MSR). On the basis of substrate stereospecificity, two types of MSR, A and B, that do not share any sequence similarity, have been identified. In the present review, we first compare the multigenic MSR families in the three plant species for which the genome is fully sequenced: Arabidopsis thaliana, Oryza sativa, and Populus trichocarpa. The MSR gene content is larger in A. thaliana (five MSRAs and nine MSRBs) compared to P. trichocarpa (five MSRAs and four MSRBs) and O. sativa (four MSRAs and three MSRBs). A complete classification based on gene structure, sequence identity, position of conserved reactive cysteines and predicted subcellular localization is proposed. On the basis of in silico and experimental data originating mainly from Arabidopsis, we report that some MSR genes display organ-specific expression patterns and that those encoding plastidic MSRs are highly expressed in photosynthetic organs. We also show that the expression of numerous MSR genes is enhanced by environmental conditions known to generate oxidative stress. Thioredoxins (TRXs) constitute very likely physiological electron donors to plant MSR proteins for the catalysis of MetSO reduction, but the specificity between the numerous TRXs and methionine sulfoxide reductases (MSRs) present in plants remains to be investigated. The essential role of plant MSRs in protection against oxidative damage has been recently demonstrated on transgenic Arabidopsis plants modified in the content of cytosolic or plastidic MSRA.

Angiotensin type-1-receptor antagonists reduce 6-hydroxydopamine toxicity for dopaminergic neurons

Angiotensin II activates (via type 1 receptors) NAD(P)H-dependent oxidases, which are a major source of superoxide, and is relevant in the pathogenesis of several cardiovascular diseases and certain degenerative changes associated with ageing. Given that there is a brain renin-angiotensin system and that oxidative stress is a key contributor to Parkinson's disease, we investigated the effects of angiotensin II and angiotensin type 1 (AT(1)) receptor antagonists in the 6-hydroxydopamine model of Parkinson's disease. Rats subjected to intraventricular injection of 6-hydroxydopamine showed bilateral reduction in the number of dopaminergic neurons and terminals. Injection of angiotensin alone did not induce any significant effect. However, angiotensin increased the toxic effect of 6-hydroxydopamine. Rats treated with the AT(1) receptor antagonist ZD 7155 and then 6-hydroxydopamine (with or without exogenous administration of angiotensin) showed a significant reduction in 6-hydroxydopamine-induced oxidative stress (lipid peroxidation and protein oxidation) and dopaminergic degeneration. Dopaminergic degeneration was also reduced by the NAD(P)H inhibitor apocynin. Angiotensin may play a pivotal role, via AT(1) receptors, in increasing the oxidative damage of dopaminergic cells, and treatment with AT(1) antagonists may reduce the progression of Parkinson's disease.

Thioredoxin m4 controls photosynthetic alternative electron pathways in Arabidopsis

In addition to the linear electron flow, a cyclic electron flow (CEF) around photosystem I occurs in chloroplasts. In CEF, electrons flow back from the donor site of photosystem I to the plastoquinone pool via two main routes: one that involves the Proton Gradient Regulation5 (PGR5)/PGRL1 complex (PGR) and one that is dependent of the NADH dehydrogenase-like complex. While the importance of CEF in photosynthesis and photoprotection has been clearly established, little is known about its regulation. We worked on the assumption of a redox regulation and surveyed the putative role of chloroplastic thioredoxins (TRX). Using Arabidopsis (Arabidopsis thaliana) mutants lacking different TRX isoforms, we demonstrated in vivo that TRXm4 specifically plays a role in the down-regulation of the NADH dehydrogenase-like complex-dependent plastoquinone reduction pathway. This result was confirmed in tobacco (Nicotiana tabacum) plants overexpressing the TRXm4 orthologous gene. In vitro assays performed with isolated chloroplasts and purified TRXm4 indicated that TRXm4 negatively controls the PGR pathway as well. The physiological significance of this regulation was investigated under steady-state photosynthesis and in the pgr5 mutant background. Lack of TRXm4 reversed the growth phenotype of the pgr5 mutant, but it did not compensate for the impaired photosynthesis and photoinhibition sensitivity. This suggests that the physiological role of TRXm4 occurs in vivo via a mechanism distinct from direct up-regulation of CEF.

Specificity of thioredoxins and glutaredoxins as electron donors to two distinct classes of Arabidopsis plastidial methionine sulfoxide reductases B

Methionine sulfoxide reductases (MSRs) A and B reduce methionine sulfoxide (MetSO) S- and R-diastereomers, respectively, back to Met using electrons generally supplied by thioredoxin. The physiological reductants for MSRBs remain unknown in plants, which display a remarkable variety of thioredoxins (Trxs) and glutaredoxins (Grxs). Using recombinant proteins, we show that Arabidopsis plastidial MSRB1 and MSRB2, which differ regarding the number of presumed redox-active cysteines, possess specific reductants. Most simple-module Trxs, especially Trx m1 and Trx y2, are preferential and efficient electron donors towards MSRB2, while the double-module CDSP32 Trx and Grxs can reduce only MSRB1. This study identifies novel types of reductants, related to Grxs and peculiar Trxs, for MSRB proteins displaying only one redox-active cysteine.

The Arabidopsis thaliana sulfiredoxin is a plastidic cysteine-sulfinic acid reductase involved in the photooxidative stress response

The 2-cysteine peroxiredoxins (2-Cys-Prxs) are antioxidants that reduce peroxides through a thiol-based mechanism. During catalysis, these ubiquitous enzymes are occasionally inactivated by the substrate-dependent oxidation of the catalytic cysteine to the sulfinic acid (-SO2H) form, and are reactivated by reduction by sulfiredoxin (Srx), an enzyme recently identified in yeast and in mammal cells. In plants, 2-Cys-Prxs constitute the most abundant Prxs and are located in chloroplasts. Here we have characterized the unique Srx gene in Arabidopsis thaliana (AtSrx) from a functional point of view, and analyzed the phenotype of two AtSrx knockout (AtSrx-) mutant lines. AtSrx is a chloroplastic enzyme displaying sulfinic acid reductase activity, as shown by the ability of the recombinant AtSrx to reduce the overoxidized 2-Cys-Prx form in vitro, and by the accumulation of the overoxidized Prx in mutant lines lacking Srx in vivo. Furthermore, AtSrx mutants exhibit an increased tolerance to photooxidative stress generated by high light combined with low temperature. These data establish that, as in yeast and in mammals, plant 2-Cys-Prxs are subject to substrate-mediated inactivation reversed by Srx, and suggest that the 2-Cys-Prx redox status and sulfiredoxin are parts of a signaling mechanism participating in plant responses to oxidative stress.

Angiotensin-converting enzyme inhibition reduces oxidative stress and protects dopaminergic neurons in a 6-hydroxydopamine rat model of Parkinsonism

It is now established that the brain possesses a local renin-angiotensin system and that angiotensin II exerts multiple actions in the nervous system, including regulation of striatal dopamine release. Furthermore, angiotensin activates NADPH-dependent oxidases, which are a major source of superoxide, and angiotensin-converting enzyme inhibitors, commonly used in the treatment of hypertension and chronic heart failure, have shown antioxidant properties in several tissues. Oxidative stress is a key contributor to the pathogenesis and progression of Parkinson's disease. In the present study, we treated rats with intraventricular injections of the dopaminergic neurotoxin 6-hydroxydopamine and subcutaneous injections of the angiotensin-converting enzyme inhibitor Captopril to study the possible neuroprotective effect of the latter on the dopaminergic system and on 6-hydroxydopamine-induced oxidative stress. Rats treated with Captopril and 6-hydroxydopamine showed significantly less reduction in the number of dopaminergic neurons (i.e., immunoreactive to tyrosine hydroxylase) in the substantia nigra and in the density of striatal dopaminergic terminals than 6-hydroxydopamine-lesioned rats not treated with Captopril. In addition, Captopril reduced the levels of major oxidative stress indicators (i.e., lipid peroxidation and protein oxidation) in the ventral midbrain and the striatum of 6-hydroxydopamine-lesioned rats. Our results suggest that angiotensin-converting enzyme inhibitors may be useful for treatment of Parkinson's disease and that further investigation should focus on the neuroprotective capacity of these compounds.