Received: 10/10/2025 Accepted: 24/01/2026 Published: 10/02/2026 1 of 8

https://doi.org/10.52973/rcfcv-e361824 RevistaCientíca,FCV-LUZ/Vol.XXXVI

ABSTRACT

This study aims to investigate the effects of bupivacaine-

induced toxicity on renal tissue and the potential protective role

of intravenous lipid emulsion. 28 adult male Wistar Albino rats

were randomly assigned to four groups as follows: Control, local

anesthesia, intravenous lipid emulsion, and local anesthesia

+ intravenous lipid emulsion. Group local anesthesia received

a 3μg·kg

-1

·min

-1

bupivacaine infusion, group intravenous lipid

emulsion received a 1.5 mL bolus followed by 0.25μg·kg

-1

·min

-1

intravenous lipid emulsion infusion, and group local anesthesia +

intravenous lipid emulsion received bupivacaine with intravenous

lipid emulsion intervention upon toxicity signs. All animals

were closely monitored throughout the study. In group local

anesthesia, bupivacaine induced signicant renal alterations

histopathologically, and increased irisin, matrix metalloproteinase-9

(MMP-9), nuclear factor-kappa B (NF-κB), and tumor necrosis

factor-α (TNF-α) immunoreactivity compared to control

(P<0.05). Histopathology revealed marked edema, congestion,

tubular degeneration, inflammatory cell inltration, glomerular

degeneration, and tubular cell shedding (P<0.001). Conversely, rats

in the local anesthesia + intravenous lipid emulsion group showed

decreased renal tissue edema and congestion, attenuated tubular

degeneration, and reduced inltration, glomerular degeneration,

and tubular cell shedding, and reduced immunoreactivity of irisin,

MMP-9, NF-κB, and TNF-α (P<0.001), indicating a nephroprotective

effect of intravenous lipid emulsion. These ndings suggest that

irisin, MMP-9, NF-κB, and TNF-α serve as reliable biomarkers of

bupivacaine-induced nephrotoxicity. Intravenous lipid emulsion

administration mitigates these biochemical and histopathological

changes, highlighting its potential as a protective agent against

local anesthetic-induced renal damage. The study underscores the

importance of monitoring these biomarkers and provides evidence

for the therapeutic benets of intravenous lipid emulsion in the

management of bupivacaine toxicity.

Key words: Intravenous lipid emulsion; irisin; MMP-9; NF-κB;

TNF-α

RESUMEN

Este estudio investigó los efectos de la toxicidad inducida por

bupivacaína en el tejido renal y el posible papel protector de la

emulsión lipídica intravenosa. Veintiocho ratas Wistar Albino macho

adultas fueron asignadas aleatoriamente a cuatro grupos: Control,

anestesia local, emulsión lipídica intravenosa y anestesia local +

emulsión lipídica intravenosa. El grupo anestesia local recibió una

infusión de bupivacaína de 3 μg·kg

-1

·min

-1

, el grupo emulsión lipídica

intravenosa recibió un bolo de 1,5 mL seguido de una infusión de

emulsión lipídica intravenosa de 0,25μg·kg

-1

·min

-1

, y el grupo

anestesia local + emulsión lipídica intravenosa recibió bupivacaína

con intervención de emulsión lipídica intravenosa al observar signos

de toxicidad. Todos los animales fueron monitoreados de cerca

durante el estudio. En el grupo anestesia local, la bupivacaína indujo

alteraciones renales signicativas, incluyendo un aumento en la

inmunorreactividad de irisina, metaloproteinasa de matriz-9, factor

nuclear kappa B y factor de necrosis tumoral-α en comparación con

los controles (P<0,05). La histopatología reveló edema, congestión,

degeneración tubular, inltración, degeneración glomerular y

desprendimiento de células tubulares signicativos (P<0,001).

Por el contrario, las ratas del grupo anestesia local + emulsión

lipídica intravenosa mostraron disminución del edema y congestión

renal, atenuación de la degeneración tubular y reducción de la

inltración, degeneración glomerular y desprendimiento celular

tubular (P<0,001), indicando un efecto nefroprotector de emulsión

lipídica intravenosa. Estos hallazgos sugieren que irisina, factor

nuclear kappa B, metaloproteinasa de matriz-9 y factor de necrosis

tumoral-α son biomarcadores ables de la nefrotoxicidad inducida

por bupivacaína. La administración de emulsión lipídica intravenosa

atenúa estos cambios bioquímicos e histopatológicos, destacando

su potencial como agente protector frente al daño renal inducido por

anestésicos locales. El estudio subraya la importancia de monitorear

estos biomarcadores y proporciona evidencia de los benecios

terapéuticos de emulsión lipídica intravenosa en el manejo de la

toxicidad por bupivacaína.

Palabras clave: Emulsión lipídica intravenosa; irisina; MMP-9;

NF-κB; TNF-α

Effects of intravenous lipid emulsions on irisin, MMP-9, NF-κB, TNF-α in

rat kidneys with bupivacaine toxicity: An immunohistochemical study

Efectos de emulsiones lipídicas intravenosas sobre irisin, MMP-9, NF-κB, TNF-α en riñones

de ratas con toxicidad por bupivacaína: estudio inmunohistoquímico

Fadime Tosun

* , Nezir Yilmaz

, Gülsen Bayrak

, Mevlüt Doğukan

, Mehmet Duran

, Zeliha Bozkurt

Adıyaman University, Faculty of Medicine, Anesthesiology and Reanimation Department. 02100 Adıyaman, Türkiye.

Uşak University, Faculty of Medicine, Histology and Embryology Department. 64000 Uşak, Türkiye.

*Corresponding author: fadimetosun@gmail.com

Renal impact of intravenous lipid solution in Bupivacaine toxicity / Tosun et al.____________________________________________________

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INTRODUCTION

Local anesthetics (LA) are drugs that temporarily inhibit some

or all of the sensory, motor, or autonomic functions [1] and are

widely used in local/regional anesthesia and postoperative pain

management. Although adverse side effects are rare, the increased

prevalence of their use has led to a higher incidence of local

anesthetic systemic toxicity (LAST), most frequently triggered by

inadvertent intravascular injection or the use of excessively high

doses during application [2].

Local anesthetic systemic toxicity can impair perfusion and

function of vital organs such as the central nervous system,

kidneys, and cardiovascular system [3], potentially resulting in

organ failure [4]. High-dose LA induces molecular and cellular

changes in renal cells, including inflammation and apoptosis,

contributing to renal injury [5].

Various biomarkers and molecular analyses have been explored

to clarify these mechanisms, including the myokine irisin [5] and

matrix metalloproteinase-9 (MMP-9) [6], tumor necrosis factor

alpha (TNF-α) and nuclear factor kappa B (NF-κB) are key mediators

of kidney damage [7, 8]; TNF-α initiates inflammation and activates

NF-κB [9, 10], which sustains inflammation via upregulation of

MMP-9 and other genes [11]. Irisin may modulate these processes

by balancing TNF-α/NF-κB pathways [10, 12].

In severe instances of LAST, insufcient or delayed intervention

may lead to renal and systemic complications, ultimately progressing

to cardiac arrest and even death [2, 13]. The American Society of

Regional Anesthesia emphasizes early airway management and

prompt intralipid emulsion (ILE) therapy in LAST to prevent the

harmful cycle of hypoxia and acidosis in advanced toxicity [14].

Evidence supports ILE use in bupivacaine-induced LAST [15,

16], though its effects on renal tissue remain underexplored. This

study aims to characterize bupivacaine-induced renal toxicity and

evaluate the potential protective effects of ILE on these alterations.

MATERIALS AND METHODS

This study was approved by the Animal Studies Ethics Committee

of Adıyaman University (ADIYAMAN-HADYEK: 06.06.2024–

2023/014), and all procedures followed NIH guidelines for

laboratory animal care. Twenty-eight adult male Wistar-Albino

rats (300–350 g) were used, provided with standard diet and

water ad libitum, and maintained under controlled temperature

(22–25°C), humidity (50–55%), and a 12-hour light/dark cycle.

Sample size calculation, based on previously published

myocardial bupivacaine data [17], indicated that seven rats per

group were sufcient to detect an effect size of 1.55 with 80%

statistical power and 5% type I error rate. This sample size was

therefore considered adequate to ensure the statistical validity

and reliability of the research ndings.

Rats were anesthetized under Veterinary supervision with

intramuscular Xylazine hydrochloride (Rompun, Bayer Turkish

Pharmaceutical Co. Ltd., 20 mg·kg

-1

) and Ketamine hydrochloride

(Ketalar, Eczacıbaşı, Istanbul, Türkiye, 50 mg·kg

-1

). Subjects were

randomly assigned to four groups (n = 7 each):

○

Control (Group C): Rats in this group did not receive any

treatment [18].

○

Local Anesthesia (Group LA): In this group, rats were

provided with intravenous access via the tail vein. Following

anesthesia and cardiac monitoring, a continuous bupivacaine

infusion (Marcaine 0.5%, AstraZeneca Ltd, Istanbul, Türkiye)

was administered at 3 μg·kg

-1

·min

-1

to induce experimental

LAST and to monitor the onset of cardiac toxicity symptoms.

The infusion was discontinued immediately upon the

appearance of arrhythmia or bradycardia [19].

○

Intravenous Lipid Emulsion (Group ILE): Rats received

intravenous access through the tail vein, and after anesthesia

and cardiac monitoring, a bolus of 1.5 mL·kg

-1

ILE (Intralipid®

20%, soybean oil–based intravenous lipid emulsion,

Fresenius Kabi AB, Uppsala, Sweden) was given, followed

by a continuous infusion at 0.25 μg·kg

-1

·min

-1

for 15 min.

○

Local Anesthesia + Intravenous Lipid Emulsion (Group

LA + ILE): In this group, following anesthesia and cardiac

monitoring, rats rst received a continuous intravenous

bupivacaine infusion via the tail vein (Marcaine® 0.5%,

AstraZeneca Ltd, Istanbul, Türkiye) until arrhythmia

or bradycardia was observed. Immediately after the

bupivacaine infusion was stopped, a bolus of 1.5 mL·kg

-1

ILE (Intralipid® 20%, Fresenius Kabi AB, Uppsala, Sweden)

was administered via the same intravenous route, followed

by a continuous infusion at 0.25 μg·kg

-1

·min

-1

for 15 min.

Oxygen support was provided throughout, and the infusion

was terminated once hemodynamic stability was achieved.

Kidneys were harvested from all animals under deep anesthesia:

in the LA group immediately after the onset of cardiac toxicity

(bradycardia), in the ILE and LA + ILE groups after completion

of the ILE infusion, and in the control group at the end of the

experimental procedures. Euthanasia was performed immediately

after tissue collection, and kidneys were placed in freshly prepared,

phosphate-buffered 10% formalin for histological analysis.

Histological analyses

Kidney tissue samples were xed in 10% formaldehyde for

further analysis. After xation, tissue samples underwent routine

processing, then were parafn-embedded and blocked. 5 µm

thickness sections were obtained from these blocks using a

microtome (ThermoScientic, HM325, USA). For the morphological

evaluation, the sections were stained with Hematoxylin &

Eosin (H&E).

Morphological alterations were scored semi-quantitatively for

parameters including edema, congestion, tubular degeneration,

inflammatory cell inltration, glomerular degeneration, and tubular

cell detachment using a light microscope (Nikon ECLIPSE E200,

Japan) and photographed. The semi-quantitative scoring system

was dened as follows: 0 = no damage, 1 = ≤10%, 2 = 10–25%, 3

= 25–50%, 4 = 50–75%, and 5 = > 75% histopathological damage.

This scoring system was adapted and modied from previously

published rat kidney histopathology studies [20].

Renal impact of intravenous lipid solution in Bupivacaine toxicity / Tosun et al.____________________________________________________

_______________________________________________________________________________________________Revista Cientica, FCV-LUZ / Vol. XXXVI

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Immunohistochemical evaluation

Immunohistochemical staining was carried out as previously

reported using the avidin-biotin-peroxidase complex method

[21, 22]. 5 µm thickness sections were deparaffinized.

Primary antibodies were diluted 1:200 using a commercial kit

(ThermoScientic™ TP-015-HA) to detect the following proteins:

Irisin (Rabbit Polyclonal, H-067–17, PhoenixPharmaceuticals Inc.,

California, USA), MMP-9 (Rabbit Polyclonal, BS-4593R, Bioss Inc.,

Massachusetts, USA), TNF-α (Rabbit Monoclonal IgG, ab220210,

Abcam, Cambridge, UK), and NF-κB (Rabbit Monoclonal IgG,

ab32536, Abcam, Cambridge, UK).

After application of the 3-Amino-9-Ethylcarbazole chromogen

(AEC), the sections were counterstained with Mayer’s hematoxylin.

Then the immunostained tissues were examined under a light

microscope and photographed. A histoscore was calculated

based on the extent (0.1: < 25%, 0.4: 26–50%, 0.6: 51–75%,

0.9: 76–100%) and intensity (0: none, +0.5: very weak, +1: weak,

+2: moderate, +3: strong) of immunoreactivity. The histoscore

was determined using the following formula: Histoscore = extent

× intensity [23].

Statistical analysis

Statistical analyses were performed using SPSS version 22.

Continuous data were expressed as median and range (minimum–

maximum). For comparisons among more than two groups, the

Kruskal-Wallis test was applied. Pairwise comparisons following

the Kruskal-Wallis test were performed using Dunn’s post hoc

test. Dependent variables were analyzed with Two-Related-

Samples Tests, and a P-value of less than 0.05 was considered

statistically signicant.

RESULTS AND DISCUSSION

The experiment started with 28 subjects and ended with the

same number.

Histopathological Findings

Histopathological analysis presented that kidney tissues

from the control and ILE groups exhibited normal architecture,

including glomeruli, cortical and medullary tubules, and peritubular

regions, with no statistically signicant differences between these

groups (P=0.802). Compared to the control group, in the LA group

demonstrated marked renal injury, including edema, congestion,

tubular degeneration, inflammatory cell inltration, glomerular

degeneration, and tubular cell detachment (P<0.001).

Notably, these alterations were signicantly attenuated in the

LA + ILE group, with reductions in edema, congestion, tubular

degeneration, and inflammatory changes (P<0.001) (TABLE 1

and FIG. 1).

Local anesthetics are widely applied in clinical practice; however,

use of LA, especially at high concentrations, may induce detrimental

effects on renal tissue. These effects can result from direct

cytotoxic mechanisms or indirect physiological disruptions. Lee

et al. [5] demonstrated that lidocaine, bupivacaine, and tetracaine

induced apoptosis in a concentration-dependent manner, leading

to kidney damage by impairing both the structural and functional

integrity of renal cells.

Additionally, in a study by Chen and Zhuang [24] neurotoxicity was

induced in mice through bupivacaine application, which led to an

excessive inflammatory response that could potentially kidney tissue

injury. In the present study, histopathological changes consistent

with these reports were observed, indicating that bupivacaine

induces renal damage. Furthermore, administration of ILE mitigated

bupivacaine-induced renal injury. Reductions in edema, tubular

degeneration, and inflammatory cell inltration in the LA + ILE

group reveal that ILE may counteract both the direct cytotoxic and

indirect inflammatory effects of high-dose bupivacaine [14, 16].

These results highlight the critical importance of timely

intervention in cases of LAST. Rapid administration of therapeutic

measures, such as intravenous lipid emulsions, is essential to

prevent both systemic and organ-specic toxic effects. Delayed

intervention can allow the accumulation of the anesthetic in

the circulation and target organs, exacerbating cardiotoxicity,

neurotoxicity, and renal injury. Therefore, early recognition and

prompt treatment are crucial to minimize adverse outcomes and

improve overall safety in experimental and clinical settings.

Immunohistochemical ndings

Immunohistochemical analysis demonstrated the expression

of irisin (FIGS. 2. 1a to 1d), MMP-9 (FIGS. 2. 2a to 2d), NF-κB

(FIGS. 2. 3a to 3d), TNF-α (FIGS. 2. 4a to 4d) in kidney tissues

under light microscopy. Immunoreactivity was similar between

the control (FIG. 2. 1a, 2a, 3a, 4a) and ILE groups (FIG. 2. 1d, 2d,

3d, 4d), with no signicant differences observed (P>0.05, FIG. 3).

In contrast, the LA group (FIG. 2. 1b, 2b, 3b, 4b) showed markedly

TABLE I

Semiquantitative scoring of kidney tissues of rats from all groups

Groups

Edema

Median (min-max)

Congestion

Median (min-max)

Tubular degeneration

Median (min-max)

Inltration

Median (min-max)

Glomerular degeneration

Median (min-max)

Tubular cell shedding

Median (min-max)

Control 0.00 (0.00–1.00) 0 0 0.00 (0.00–1.00) 0.00 (0.00–1.00) 0

LA 4.00 (3.00–5.00)

4.00 (3.00–5.00)

2.00 (2.00–3.00)

2.00 (2.00–4.00)

3.00 (2.00–3.00)

3.00 (2.00–4.00)

LA+ILE 2.00 (2.00–3.00)

1.00 (1.00–2.00)

2.00 (1.00–2.00)

1.00 (1.00–2.00)

1.00 (0.00–1.00)

ILE 0.00 (0.00–1.00) 0 0.00 (0.00–1.00) 0 0 0

Valuesaresummarizedasmedian(min–max).

Signicantlydierentfromthecontrolgroup,and

SignicantlydierentfromtheLAgroup(P<0.01)

Renal impact of intravenous lipid solution in Bupivacaine toxicity / Tosun et al.____________________________________________________

4 of 8 5 of 8

FIGURE 1. H&E staining of control (a), LA (b), LA+ILE (c), and ILE (d) groups. Normal morphology in kidneys of

control and ILE; in the LA group, glomerular degeneration (arrowhead), tubular degeneration (red arrow),

inammatory inltration (asterisk), and vascular congestion (black arrow), reduced pathology in LA+ILE.

Scale bar: 250 µm, magnication 100×

Control group LA group LA + ILE group ILE group

IrisinMMP-9NF-κBTNF-α

FIGURE 2. Immunohistochemical staining of irisin (1a–1d), MMP-9 (2a–2d), NF-κB (3a–3d), and TNF-α (4a–4d) in kidney tissues

showing similar expression in control and ILE, increased in LA, and reduced in LA + ILE (Immunohistochemical staining, AEC

chromogen, Mayer's Hematoxylin, Scale bar: 100 μm, 400× magnication)

c d

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_______________________________________________________________________________________________Revista Cientica, FCV-LUZ / Vol. XXXVI

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elevated immunoreactivities for all markers compared to the control

group (P<0.05, FIG. 3). Administration of ILE in the LA + ILE group

(FIG. 2. 1c, 2c, 3c, 4c) signicantly attenuated these increases

compared with the LA group, suggesting a protective effect against

bupivacaine-induced renal alterations (P<0.05, FIG. 3).

progression of renal cortical brosis [6]. MMP-9 has also been

implicated in the brosis of the lungs, liver, myocardial infarction,

and chronic kidney disease [38].

In this study, the increased MMP-9 immunoreactivity in the

LA group indicates kidney damage caused by bupivacaine,

while the reduction in MMP-9 immunoreactivity following ILE

administration suggests that ILE protects against bupivacaine-

induced kidney injury.

The TNF-α is a pro-inflammatory cytokine that activates

intracellular signaling pathways, including the transcription factor

NF-κB, and contributes signicantly to inflammatory processes

implicated in renal injury [9, 10]. Although bupivacaine toxicity

has been associated with neurotoxicity via TNF-α and NF-κB

activation [24], immunohistochemical evidence regarding their

role in kidney damage is limited. In this study, increased NF-κB

and TNF-α immunoreactivity in the LA group reveals that local

anesthetic-induced inflammation contributes to renal damage.

These ndings emphasize the importance of the TNF-α and

NF-κB pathways in the pathogenesis of kidney injury. Agents that

inhibit NF-κB activation or TNF-α production have been reported

to offer protective effects in various experimental models. Studies

have shown that compounds such as pioglitazone [39], sevoflurane

[40], calycosin [9], neuropeptide Y [41], puerarin [42], chlorogenic

acid [43], and bicyclol [44] present anti-inflammatory, antibrotic,

antioxidant, and immunomodulatory properties by signicantly

reducing TNF-α and NF-κB expression. Targeting these pathways

may therefore represent a feasible strategy for preventing or

alleviating kidney damage associated with local anesthetic toxicity.

In the present study, administration of ILE reduced the

immunoreactivity of both NF-κB and TNF-α, indicating a protective

effect against bupivacaine-induced kidney injury. While some

local anesthetics at clinical doses, such as articaine [45], procaine

[46], lidocaine [47], and ropivacaine [48], can reduce NF-κB and

TNF-α expression and alleviate inflammation, the toxic dose of

bupivacaine used in this study is much higher than clinical levels,

which likely overwhelms the regulatory mechanisms and leads to

increased expression of these inflammatory markers, resulting in

nephrotoxicity. TNF-α activation consequently promotes NF-κB

signaling, which induces the synthesis of enzymes such as matrix

metalloproteinases, including MMP-9, thereby enhancing tissue

injury and inflammation [11].

In another study, ischemia-reperfusion injury in rabbit kidneys

were shown to activate NF-κB [49], and exogenous TNF-α application

in proximal tubule cells increased inflammatory mediators, including

MMP-9, causing the exacerbation of renal damage [50]. In line

with these reports, increased immunoreactivity of TNF-α, NF-κB,

and MMP-9 in the LA group led to kidney injury, whereas ILE

administration reduced these effects, implying a protective role.

The NF-κB and TNF-α also play crucial roles in promoting both

inflammation and apoptosis during kidney injury. Irisin has been

reported to exert protective effects by inhibiting these processes

[10, 12]. In present study, increased immunoreactivity of NF-κB,

irisin, and TNF-α in the LA group may reflect a compensatory

protective response of irisin against bupivacaine toxicity. In

contrast, the LA + ILE group exhibited reduced immunoreactivity

Irisin a proteolytic fragment of Fndc5 [25], is expressed in

multiple tissues, including the liver, heart, and kidneys [26, 27],

and exhibits anti-inflammatory, anti-apoptotic [10], antioxidant

[28], and anti-brotic effects [29]. Recent studies have shown

that local anesthetics can induce renal cell apoptosis, serving as

a marker for kidney damage [5].

Peng et al. [30] and Liu et al. [31] reported that irisin reduced

kidney histopathological alterations and brosis in mice and acted

as a myokine protecting against ischemia-reperfusion injury,

respectively. In the present study, immunoreactivity of irisin

increased in the LA group, indicating a potential protective response

to bupivacaine-induced toxicity, whereas the decrease in the LA + ILE

group suggests mitigation of kidney damage following ILE infusion.

The matrix metalloproteinase-9 is an endopeptidase that is

responsible for the degradation of the extracellular matrix. Its ability

to activate cytokines [32] and its pivotal role in various physiological

and pathological processes have been well-documented [33, 34].

While some studies demonstrate that MMP-9 may help protect

kidney function [35, 36], most studies highlight its harmful effects.

Wang et al. [37] observed that mice decient in MMP-9 had

a lower likelihood of developing morphological damage and

displayed milder renal interstitial brotic lesions in an obstructive

nephropathy model. Another study reported that reperfusion injury

after acute myocardial ischemia was associated with elevated levels

of inflammatory cytokines and MMP-9 in both the myocardium

and renal cortex, initiating signaling pathways implicated in the

FIGURE 3. Irisin, MMP-9, NF-κB, TNF-α immunostaining histoscore levels of

all groups. *Signicant dierence compared with the control group (P<0.05).

#Signicant dierence compared with the LA group (P<0.05)

Renal impact of intravenous lipid solution in Bupivacaine toxicity / Tosun et al.____________________________________________________

6 of 8 7 of 8

of these biomarkers, indicating that ILE infusion improves

bupivacaine-induced renal damage.

Lipid emulsion therapy is an established treatment for LAST. It

facilitates the binding and removal of lipophilic local anesthetics

from critical organs, including the kidneys [51]. Previous studies

reported that bupivacaine-induced toxicity causes signicant

bradycardia in rats [19], and ILE effectively treats early

cardiovascular depression before cardiac arrest [51].

Administration of ILE during the initial stages of LAST, such

as arrhythmias and bradycardia, helps maintain hemodynamic

stability [51, 52]. Experimental evidence also demonstrates

that ILE accelerates bupivacaine clearance and reduces its

concentrations in critical tissues, including the heart, brain, and

kidneys [53]. In the present study, ILE reduced TNF-α, NF-κB, and

MMP-9 immunoreactivity, supporting its protective and therapeutic

potential against bupivacaine-induced kidney injury.

High plasma concentrations of bupivacaine have been shown

to induce necrotic cell death and inflammatory responses,

resulting in severe tubular necrosis, medullary congestion, and

hemorrhage in rat kidneys [5]. The findings of this study are

consistent with these observations and demonstrate that ILE can

attenuate such effects. Bupivacaine and other local anesthetics

are metabolized by hepatic microsomal enzymes, and both the

parent compounds and their metabolites are eliminated via the

kidneys. The immunohistochemical markers used in this study,

including irisin, MMP-9, NF-κB, and TNF-α, reflect renal tissue

damage caused by these agents.

A limitation of this study is that ILE’s renal effects were assessed

over a short duration. Therefore, long-term outcomes and potential

side effects may have been overlooked. Additionally, results

obtained from animal models may not fully translate to humans

and should be interpreted cautiously in clinical contexts. Further

studies are warranted to evaluate the long-term efcacy and safety

of ILE in preventing local anesthetic-induced kidney injury.

CONCLUSION

The study suggests that irisin, MMP-9, NF-κB, and TNF-α are

signicant biomarkers of LA-induced renal injury. The decrease

in these parameters following ILE administration reflects its

nephroprotective effect. Furthermore, ILE appears to modulate

bupivacaine-induced renal toxicity and ameliorate histopathological

changes, including inflammation, glomerular degeneration, tubular

damage, and congestion.

Funding

There were no specic sources of funding for this study.

Conflict of interests

The authors have no conflict of interest to declare concerning

the authorship or publication of this article.

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