Antioxidative Effects of Tetramethylpyrazine on Acute Ethanol-Induced Lipid Peroxidation

Bibliometric analysis of research progress on tetramethylpyrazine and its effects on ischemia-reperfusion injury

In recent decades, natural products have attracted worldwide attention and become one of the most important resources for pharmacological industries and medical sciences to identify novel drug candidates for disease treatment. Tetramethylpyrazine (TMP) is an alkaloid extracted from Ligusticum chuanxiong Hort., which has shown great therapeutic potential in cardiovascular and cerebrovascular diseases, liver and renal injury, as well as cancer. In this review, we analyzed 1270 papers published on the Web of Science Core Collection from 2002 to 2022 and found that TMP exerted significant protective effects on ischemia-reperfusion (I/R) injury that is the cause of pathological damages in a variety of conditions, such as ischemic stroke, myocardial infarction, acute kidney injury, and liver transplantation. TMP is limited in clinical applications to some extent due to its rapid metabolism, a short biological half-life and poor bioavailability. Obviously, the structural modification, administration methods and dosage forms of TMP need to be further investigated in order to improve its bioavailability. This review summarizes the clinical applications of TMP, elucidates its potential mechanisms in protecting I/R injury, provides strategies to improve bioavailability, which presents a comprehensive understanding of the important compound. Hopefully, the information and knowledge from this review can help researchers and physicians to better improve the applications of TMP in the clinic.

Ligustrazine improves the compensative effect of Akt survival signaling to protect liver Kupffer cells in trauma-hemorrhagic shock rats

Trauma-hemorrhagic shock (THS) is a medical emergency that is encountered by physicians in the emergency department. Chuan Xiong is a traditional Chinese medicine and ligustrazine is a natural compound from it. Ligustrazine improves coronary blood flow and reduces cardiac ischemia in animals through Ca2+ and ATP-dependent vascular relaxation. It also decreases the platelets' bioactivity and reduces reactive oxygen species formation. We hypothesized that ligustrazine could protect liver by decreasing the inflammation response, protein production, and apoptosis in THS rats. Ligustrazine at doses of 100 and 1000 μg/mL was administrated in Kupffer cells isolated from THS rats. The protein expressions were detected via western blot. The THS showed increased inflammation response proteins, mitochondria-dependent apoptosis proteins, and had a compensation effect on the Akt pathway. After ligustrazine treatment, the hemorrhagic shock Kupffer cells decreased inflammatory response and mitochondria-dependent apoptosis and promoted a more compensative effect of the Akt pathway. It suggests ligustrazine reduces inflammation response and mitochondria-dependent apoptosis induced by THS in liver Kupffer cells and promotes more survival effects by elevating the Akt pathway. These findings demonstrate the beneficial effects of ligustrazine against THS-induced hepatic injury, and ligustrazine could be a potential medication to treat the liver injury caused by THS.

Hybrid molecules of scutellarein and tertramethylpyrazine's active metabolites for ischemic stroke

A series of hybrid molecules of scutellarein and tertramethylpyrazine's active metabolites have been synthesized. Compared to the original compound, these prepared compounds exhibited higher water solubility, more appropriate logP and better stability. Importantly, compounds 11b, 11d and 11e showed improved neuroprotective activity against the H₂O₂-induced cell death in PC12 cells, and better antithrombosis activity. The optimized compound 11b was further evaluated by cerebral ischemia/ reperfusion in the middle cerebral artery occlusion (MCAO) model, the results showed that the compound could significantly reduce the infarct area and decrease the neuronal cell damage in CA1 pyramidal neurons. Overall, we demonstrated that the twin drug strategy could be applied in the development of agents for the treatment of ischemic stroke.

Evaluation of five additives to mitigate toxicity of cryoprotective agents on porcine chondrocytes

Cryoprotective agents (CPAs) are used in cryopreservation protocols to achieve vitrification. However, the high CPA concentrations required to vitrify a tissue such as articular cartilage are a major drawback due to their cellular toxicity. Oxidation is one factor related to CPA toxicity to cells and tissues. Addition of antioxidants has proven to be beneficial to cell survival and cellular functions after cryopreservation. Investigation of additives for mitigating cellular CPA toxicity will aid in developing successful cryopreservation protocols. The current work shows that antioxidant additives can reduce the toxic effect of CPAs on porcine chondrocytes. Our findings showed that chondroitin sulphate, glucosamine, 2,3,5,6-tetramethylpyrazine and ascorbic acid improved chondrocyte cell survival after exposure to high concentrations of CPAs according to a live-dead cell viability assay. In addition, similar results were seen when additives were added during CPA removal and articular cartilage sample incubation post CPA exposure. Furthermore, we found that incubation of articular cartilage in the presence of additives for 2 days improved chondrocyte recovery compared with those incubated for 4 days. The current results indicated that the inclusion of antioxidant additives during exposure to high concentrations of CPAs is beneficial to chondrocyte survival and recovery in porcine articular cartilage and provided knowledge to improve vitrification protocols for tissue banking of articular cartilage.

Effect of cytokeratin 17 on retinal pigment epithelium degeneration and choroidal neovascularization

AIM

To study the effects of cytokeratin 17 (CK17) on sodium iodate (NaIO3) induced rat retinal pigment epithelium (RPE) degeneration, laser induced rat choroidal neovascularization (CNV), and oxidative stress of human retinal pigment epithelium cells (ARPE-19) and human umbilical vein endothelial cell (HUVEC).

METHODS

Thirty 8-week-old male Brown Norway rats were randomly divided into 3 groups, 10 rats in control group treated with solvent alone; 10 rats in NaIO3 group treated with solvent and 35 mg/kg NaIO3 injection through hypoglossal vein and 10 rats in CK17+NaIO3 group treated with 1% CK17 eye drop 3 times a day for 1wk before and 4wk after NaIO3 injection. RPE function was measured with c-wave of electroretinogram (ERG). Another 20 rats were randomly divided into 2 groups. Of them 10 rats in CK17 group were anesthetized to receive Nd:YAG laser and given 1% CK17 eye drop before same as above; 10 rats in control were received Nd:YAG and treated with solvent. The development of choroidal neovascularization (CNV) was determined by fundus fluorescein angiography (FFA) performed on 4wk after laser. Methylthiazoly tetrazolium (MTT) assay was used to study effect of CK17 on various oxidants induced injury in ARPE-19 and HUVEC in vitro.

RESULTS

Four weeks after NaIO3 injection, the c-wave amplitude of ERG was 0.393±0.02 V in the control group, 0.184±0.018 V in NaIO3 group and 0.3±0.01 V in CK17+NaIO3 group. There was a significant reversal of the c-wave by CK17 as compared to NaIO3 group (P<0.01). Four weeks after laser, the size of the CNV lesion was 2.57±0.27 mm(2) in control group and 1.64±0.08 mm(2) in CK17 group. The lesion size significantly diminished in CK17 group (P<0.01). The in vitro results showed CK17 also reversed the various oxidants induced injuries in ARPE-19 at the dose of 100 µg/mL and enhanced the injury in HUVECs at different concentrations.

CONCLUSION

CK17 can significantly protect RPE from NaIO3 induced degeneration in vivo and in vitro and also could reverse the various oxidants induced injuries in vitro. It inhibits the development of CNV in rat model, interfered with vascular endothelial cell proliferation in vitro.

Protective effect of tetramethylpyrazine on myocardial ischemia-reperfusion injury

Myocardial ischemia-reperfusion injury (MIRI) is a common pathological and physiological phenomenon. Tetramethylpyrazine is the extract of the traditional Chinese medicine Chuanxiong, which can exert protective effects on MIRI in multiple ways. This paper reviewed the current research progress and evidence about the cardiovascular effects of tetramethylpyrazine, which included protecting mitochondria and improving energy metabolism, scavenging oxygen free radicals (OFRs) to inhibit lipid peroxidation, attenuating calcium (Ca(2+)) overload and maintaining Ca(2+) homeostasis in cells, inhibiting apoptosis and protecting myocardial cells, interfering with the inflammatory reaction and mitigating cell injury, interfering with cell signaling pathways, and improving function of endothelial cells and protecting myocardial cells. However, further rigorously designed randomized controlled trials are warranted.

Effects of Tetramethylpyrazine on Microglia Activation in Spinal Cord Compression Injury of Mice

Secondary mechanisms, including inflammation and microglia activation, serve as targets for the development and application of pharmacological strategies in the management of spinal cord injury (SCI). Tetramethylpyrazine (TMP), an active ingredient of Ligusticum wallichii (chuanxiong), has shown anti-inflammatory and neuroprotective effects against SCI. However, it remains uncertain whether the inflammation-suppressive effects of TMP play a modulatory role over microglia activation in SCI. The present study investigated the effects of TMP on microglia activation and pro-inflammatory cytokines in spinal cord compression injury in mice. For a real-time PCR measurement of pro-inflammatory cytokines, SCI was induced in mice by the clip compression method (30 g force, 1 min) and TMP (15 or 30 mg/kg, i.p.) was administered once, 30 minutes before the SCI induction. For immunohistochemistry, TMP (30 mg/kg, i.p.) treatment was given three times during the first 48 hours after the SCI. 30 mg/kg of TMP treatment reduced the up-regulation of TNF-α, IL-1β and COX-2 mRNA in the spinal tissue at four hours after the SCI induction. TMP also significantly attenuated microglia activation and neutrophil infiltration at 48 hours after the SCI induction. In addition, iNOS expression in the spinal tissue was attenuated with TMP treatment. These results suggest that TMP plays a modulatory role in microglia activation and may protect the spinal cord from or potentially delay secondary spinal cord injury.

The effects of caloric restriction against ethanol-induced oxidative and nitrosative cardiotoxicity and plasma lipids in rats

Caloric restriction (CR) prevents or delays a wide range of aging-related diseases possibly through alleviation of oxidative stress. The aim of our study was to examine the effect of CR on oxidative and nitrosative cardiac damage in rats, induced by acute ethanol intoxication. Male Wistar rats were divided into following groups: control; calorie-restricted groups with intake of 60-70% (CR60-70) and 40-50% of daily energy needs (CR40-50); ethanol-treated group (E); calorie-restricted, ethanol-treated groups (CR60-70 + E, CR40-50 + E). Ethanol was administered in five doses of 2 g/kg every 12 h, while the duration of CR was five weeks before ethanol treatment. Malondialdehyde level was significantly lower in CR60-70 + E and significantly higher in CR40-50 + E vs. control. Nitrite and nitrate level was significantly higher in CR40-50 + E compared to control group. Activity of total superoxide dismutase (SOD) and its isoenzyme, copper/zinc-SOD (Cu/ZnSOD), was significantly higher in CR60-70 + E and lower in CR40-50 + E vs. control. Activity of manganese-SOD (MnSOD), that is also SOD isoenzyme, was significantly lower in  CR40-50 + E compared to control group. Plasma content of sulfhydryl (SH) groups was significantly higher in CR60-70 group vs. control. Plasma concentration of total cholesterol, triacylglycerol, low-density lipoproteins and high-density lipoproteins was significantly lower in CR60-70 group compared to control values. Food restriction to 60-70% of daily energy needs has a protective effect on acute ethanol-induced oxidative and nitrosative cardiac damage, at least partly due to alleviation of ethanol-induced decrease in SOD activity, while restriction to 40-50% of energy needs aggravates lipid peroxidation and nitrosative stress.

Synthesis and protective effect of new ligustrazine-benzoic acid derivatives against CoCl2-induced neurotoxicity in differentiated PC12 cells

A series of novel ligustrazine-benzoic acid derivatives were synthesized and evaluated for their protective effect against cobalt chloride-induced neurotoxicity in differentiated PC12 cells. Combining hematoxylin and eosin staining, we found compound that (3,5,6-trimethylpyrazin-2-yl)methyl 3-methoxy-4-[(3,5,6-trimethylpyrazin-2-yl)methoxy]benzoate (4a) displayed promising protective effect on the proliferation of the injured PC12 cells (EC₅₀ = 4.249 µM). Structure-activity relationships are briefly discussed.

Neuroprotective effects of tanshinone IIA and/or tetramethylpyrazine in cerebral ischemic injury in vivo and in vitro

The present study compared the potential neuroprotective effects of tanshinone (Tan) IIA monotherapy, tetramethylpyrazine (TMP) monotherapy, and Tan IIA+TMP combination therapy in adult rat subjected to cerebral ischemic injury using the permanent middle cerebral artery occlusion (MCAO) model and in primary cortical neuron culture exposed to oxygen-glucose deprivation (OGD) model. Male Sprague Dawley rats (n=84) were randomly divided into sham-operated, MCAO, cmc-Na (sodium carboxymethyl cellulose), TMP, Tan IIA+TMP, and Tan IIA groups. In agreement with the in vivo experiment, primary cortical neuron culture was prepared from one-day-old SD rats and grouped according to exposure: normoxia control (NC), OGD, dimethyl sulfoxide, TMP, Tan IIA+TMP, and Tan IIA groups. The neurological deficits and infarct volume were evaluated at 24h after the MCAO models. Oxidative stress (malondialdehyde, glutathione, and superoxide dismutase) and intracellular [Ca(2+)](i) concentration were measured through spectrophotometric analysis. Neurocyte apoptosis and viability were respectively evaluated through terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, respectively. Apoptosis factors (Bax, Bcl-2, caspase-3, and trmp-7) were analyzed using western blot and immunohistochemistry. The results suggest that Tan IIA+TMP combination therapy was more effective than TMP monotherapy but not Tan IIA monotherapy. Tan IIA monotherapy is more effective than TMP monotherapy in protecting the neuron against hypoxia/ischemia both in vitro and in vivo. Interestingly, Tan IIA significantly increased the phosphorylation of AKT in primary cortical neuronal culture exposed to OGD, which was abolished by PI3K inhibitor LY294002. The PI3K/AKT signaling pathway may be involved in the neuroprotective mechanism of Tan IIA on primary cortical neurons.

Buyang Huanwu decoction enhances cell membrane fluidity in rats with cerebral ischemia/reperfusion

After bilateral carotid artery occlusion for 30 minutes and reperfusion for 2 hours, distinct pathological changes presented in the cerebral cortex and cerebellum of rats. Compared with normal rats, nerve cell membrane fluidity significantly decreased in ischemia/reperfusion rats as detected by spin-labeling electron spin resonance, consistent with order parameter S and rotational correlation time τc measurements. Brain nerve cells from rats with ischemia/reperfusion injury were cultured with 1–100 mg/mL Buyang Huanwu decoction. Results showed that Buyang Huanwu decoction gradually increased membrane fluidity dose-dependently to normal levels, and eliminated hydroxide (OH^·) and superoxide ( O₂^·) free radicals dose-dependently. These findings suggest that Buyang Huanwu decoction can protect against cell membrane fluidity changes in rats with ischemia/ reperfusion injury by scavenging free radicals.

Novel multi-functional nitrones for treatment of ischemic stroke

Ischemic stroke resulting from obstruction of blood vessels is an enormous public health problem with urgent need for effective therapy. The co-administration of thrombolytic/antiplatelet agent and neuroprotective agent improves therapeutic efficacy and agent possessing both thrombolytic/antiplatelet and antiradical activities provides a promising strategy for the treatment of ischemic stroke. We have previously reported a novel compound, namely TBN, possessing both antiplatelet and antiradical activities, showed significant neuroprotective effect in a rat stroke model. We herein report synthesis of a series of new pyrazine derivatives, and evaluation of their biological activities. Their mechanisms of action were also investigated. Among these new derivatives, compound 21, armed with two nitrone moieties, showed the greatest neuroprotective effects in vitro and in vivo. Compound 21 significantly inhibited ADP-induced platelet aggregation. In a cell free antiradical assay, compound 21 was the most effective agent in scavenging the three most damaging radicals, namely (·)OH, O(2)(·-) and ONOO(-).

Protective effects and mechanism of tetramethylpyrazine against lens opacification induced by sodium selenite in rats

Tetramethylpyrazine (TMP), extracted from the Chinese herbal medicine Ligusticum wallichii franchat (chuan xiong in Chinese), is a potent anti-free radical and calcium antagonist. Correspondingly, two important hypotheses in the causation of cataracts are free radical toxicity and calcium ion overload. In this study we investigated the effect of TMP on lens opacification induced by sodium selenite in rats, addressing the potential of TMP eye drops to prevent and treat cataracts. Results showed that the extent of lens opacification in the untreated Normal Control group (NC group) was significantly less than that of selenite-injected untreated rats (MC group) on days 3, 5, 7 and 10 (p < 0.001), while TMP treated selenite-injected rats (TMP group) had less lens opacification than the MC group on days 3, 5, 7 and 10 (p < 0.05). Compared with the NC group, the MC group had significantly decreased activity of super-oxide dismutase (SOD), glutathione peroxidase (GSH-PX) and catalase (CAT) and significantly elevated malondialdehyde (MDA) and calcium ion content (p < 0.001). Compared with the MC group, the activity of (SOD), (GSH-PX) and (CAT) were significantly higher while (MDA) and calcium ion levels were significantly lower in the TMP group at all time points (p < 0.01). The findings demonstrate that the selenite-induced cataract rat models were successfully built and the TMP eye drops can delay lens opacification induced by sodium selenite in rats. The mechanism by which TMP preserves lens transparency from selenite treated animals is associated with the lenses' ability to maintain normal levels of activity of SOD, GSH-PX and CAT and normal concentrations of MDA and calcium ion.

Effect of Guanabenz on Rat AMD Models and Rabbit Choroidal Blood Flow

Aim:

The effects of Guanabenz, an agonist of α2-adrenergic receptors routinely used in human medicine as an antihypertensive drug, were studied on NaIO₃-induced retinal pigment epithelium (RPE) degeneration, laser-induced choroidal neovascularization (CNV) and choroidal blood flow, in animal models.

Methods:

The 35mg/kg NaIO₃-induced RPE degeneration rat eyes were instilled with 1% Guanabenz eye drops 3 times a day for 7 days before NaIO₃ injection, and then 2 to 4 weeks thereafter. RPE function was measured with c-wave of electroretinogram (ERG). Male Brown Norway rats were anesthetized to receive Nd:YAG laser to break the Bruch’s membrane. One percent Guanabenz eye drops were given likewise. The development of CNV was determined by fluorescein angiography performed on week 2 and week 4 using sodium fluorescein (FA) or fluorescein isothiocyanatedextran (FD70-FA). Colored microsphere technique was used for in vivo experiments to determine the choroidal blood flow in ocular hypertensive (40 mmHg) rabbit eyes.

Results:

The RPE function was protected significantly by Guanabenz according to the c-wave of ERG. Four weeks after NaIO₃ injection, the amplitude of ERG c-wave was 0.422±0.092 millivolts in the control group, 0.103±0.04 millivolts in the NaIO₃ group, and 0.254±0.061 millivolts in the Guanabenz+NaIO₃ group. There was a significant protection of the ERG c-wave by Guanabenz as compared to NaIO₃ group (P<0.01). The angiograms of FD70-FA showed decreased lesion size in the Guanabenz group. Four weeks after laser treatment, the size of the CNV lesion was 2.99±0.18 mm² in the control group, and 1.24±0.16 mm² in the Guanabenz group (P<0.01). The choroidal blood flow was significantly increased at 30 and 60 minutes after Guanabenz instillation as compared to corresponding controls.

Conclusions:

Guanabenz significantly protected RPE from NaIO₃-induced degeneration, inhibited the development of CNV in laser-induced rat AMD model and increased choroidal blood flow markedly in vivo.

Pharmacokinetic study of a novel stroke therapeutic, 2-[[(1,1-dimethylethyl)oxidoimino]methyl]-3,5,6-trimethylpyrazine, by a simple HPLC-UV method in rats

2-[[(1,1-dimethylethyl)oxidoimino]methyl]-3,5,6-trimethylpyrazine (TBN), a novel nitrone derivative of tetramethylpyrazine (TMP), was found to be a potent candidate compound for ischemic stroke treatment. It is currently in preclinical development as a stroke therapeutic. To study its pharmacokinetic characteristics, a simple and rapid HPLC-UV method was developed and validated to quantitatively determine TBN concentration in rat plasma. A Purospher C(18) column (150 × 4.6 mm, 5 μm) was used for analysis with a mobile phase containing methanol-potassium dihydrogen phosphate buffer solution (50 mM, pH 3.0) (45:55, v/v) and UV detection at 295 nm. The pharmacokinetic study was conducted in Sprague-Dawley rats by intravenous (i.v. 40, 80, and 160 mg/kg) and intragastric (i.g. 80 mg/kg) administration. The concentration-time profiles of TBN in plasma fitted a two-compartment model for both administration routes. The elimination half-life (T (1/2) (β)) of i.v. administration ranged from 134 to 225 min for low, middle and high dosage, and the area under the concentration-time curve from zero to infinity (AUC((0-∞))) ranged from 7,954 to 49,804 μg min/mL. Compared with the parent compound TMP, TBN showed a longer T (1/2) (β) (TBN 134.52 min, TMP 91.85 min) and a higher AUC((0-∞)) (TBN 22,687.84 μg min/mL, TMP 7,287.98 μg min/mL) after the same dosage of intravenous administration (80 mg/kg). The intragastric administration of TBN had a peak time of 21.65 min, C (max) of 41.71 μg/mL, and k (a) of 0.19 min(-1). And the absolute bioavailability was 36.02%.

Effect of Tetramethylpyrazine on RPE degeneration, choroidal blood flow and oxidative stress of RPE cells

AIM

To study the effects of Tetramethylpyrazine (TMP) on retinal pigment epithelium (RPE) degeneration, choroidal blood flow and oxidative stress of RPE cells.

METHODS

The 35mg/kg NaIO(3)-induced RPE degeneration rat eyes was given 25µg 1% TMP eye drops 3 times a day for 7 days before NaIO(3) injection, and then 2 to 4 weeks after NaIO(3) injection. RPE function was measured with c-wave of electroretinogram (ERG). Colored microsphere technique was used for in vivo experiments to determine the choroidal blood flow in ocular hypertensive (40mmHg) rabbit eyes. Methylthiazoltetrazolium (MTT) assay was used to study in vitro effect of TMP on various oxidants induced injury in the hRPE (ARPE-19 (ATCC, Manassas, VA, USA)).

RESULTS

Two weeks after NaIO(3) injection, the amplitude of ERG c-wave fell markedly in NaIO(3) group to 36% of control group(P<0.01). No apparent difference was observed in TMP+NaIO(3) group. Four weeks later, the NaIO(3) group fell to 46% of control group (P<0.01), while the TMP+NaIO(3) group fell to only 77% of control group (P<0.01). There was a 67% reversal of the ERG c-wave by TMP as compared to NaIO(3) group(P<0.01). The choroidal blood flow was significantly increased at all time points (at 30, 60 and 120 minutes after TMP instillation) as compared with corresponding controls. TMP had no effect on hypoxia-(1% O(2)), t-BHP- and H(2)O(2)-induced damage in RPE cells. 10(g/mL TMP could reverse 1 and 3mM NaN(3)-induced loss of viability of RPE by 18.5% (P<0.01) and 23% (P<0.01), respectively. 30µg/mL TMP could reverse 30 and 100mM NaIO(3) induced loss of viability of RPE by 18.1% (P<0.05) and 16.8% (P<0.01), respectively.

CONCLUSION

TMP can significantly protect RPE from NaIO(3) induced degeneration in vivo and oxidative stress in vitro and can increase choroidal blood flow markedly in vivo.

Synthesis and preliminary evaluation of neuroprotection of celastrol analogues in PC12 cells

A series of celastrol analogues were synthesized, and their neuroprotective effect against t-BHP-induced cytotoxicity was investigated in neuronal PC12 cells. Their effects on Hsp70 protein expression were quantified by Western blot analysis. The study found that compound CL12 is more effective than the parent celastrol against t-BHP-induced cytotoxicity. CL12 up-regulates Hsp70 protein expression dose-dependently. These results suggest that CL12 is a potential candidate for the intervention of neurodegenerative diseases.

Amelioration of Cisplatin-Induced Nephrotoxicity in Rats by Tetramethylpyrazine, a Major Constituent of the Chinese Herb Ligusticum wallichi

Nephrotoxicity of the anticancer drug, cisplatin (CP) involves enhanced renal generation of reactive oxygen metabolites and lipid peroxidation caused by decreased levels of antioxidants and antioxidant enzymes. Tetramethylpyrazine (TMP) is known to act as a strong antioxidant. Therefore, in the present work, we aimed at testing the possible protective or palliative effect of TMP on CP nephrotoxicity in rats. TMP was given orally at a dose of 80 mg · kg− 1 · day− 1 for 7 days. Some of these rats were given a single intraperitoneal injection of CP (or vehicle) at a dose of 6 mg/kg on Day 6 of treatment. Animals were sacrificed 6 days after CP (or vehicle) treatment, and blood, urine, and kidneys were obtained. Nephrotoxicity was assessed biochemically by measuring creatinine and urea in serum, reduced glutathione (GSH) concentration in renal cortex, by urinalysis, and histopathologically by light microscopy. CP significantly increased the concentration of urea and creatinine ( P < 0.05) by about 128% and 170%, respectively; increased urine volume and N-acetyl-β-D-glucosaminidase (NAG) activity; and significantly decreased osmolality and protein concentrations. CP treatment reduced GSH by about 34% ( P < 0.05) and superoxide dismutase (SOD) and total antioxidant activity (TOX) by about 28% and 21%, respectively ( P < 0.05). TMP pretreatment significantly mitigated all of these effects. Sections from saline- and TMP-treated rats showed apparently normal proximal tubules. However, kidneys of CP-treated rats had a moderate degree of necrosis. This was markedly reduced when CP was given after pretreatment with TMP. CP cortical concentration was not significantly altered by TMP treatment. The results suggest that TMP ameliorated the histological, physiological, and biochemical indices of nephrotoxicity in rats. Pending further pharmacological and toxicological studies, TMP may potentially be useful as a nephroprotective agent.