Introduction
Neuropathic pain has been described as “the most terrible of all tortures which a
nerve wound may inflict” [[1]]. Despite progress in the understanding of this syndrome, the mechanistic details
underlying the disease remain elusive. Neuropathic pain is generally characterized
by the sensory abnormalities such as unpleasant abnormal sensation (dysesthesia),
an increased response to painful stimuli (hyperalgesia), and pain in response to a
stimulus that does not normally provoke pain (allodynia) [[2]]. Peripheral neuropathic pain is frequently observed in patients with cancer, AIDS,
long standing diabetes, lumbar disc syndrome, herpes infection, traumatic spinal cord
injury, multiple sclerosis and stroke [[3]]. Moreover, post-thoracotomy, post-herniorrhaphy, post-mastectomy and post-sternotomy
are some other conditions often associated with peripheral neuropathy pain [[4]].
Chemotherapeutic drugs such as vincristine, paclitaxel, oxaliplatin, etc. are widely
used in management of cancers especially Hodgkins lymphoma, non-Hodgkins lymphoma
and leukemia. Unfortunately, these anti-cancer agents have been documented to produce
dose and duration dependent neurotoxicity and painful neuropathy [[5]] which limit their full exploitation in the management of tumors. Vincristine is
unique among the chemotherapeutic agents that it produces predictably and uniformly
neurotoxicity in all the patients even at the therapeutic doses [[6]]. This peripheral neuropathy is dose-related with a marked variability in individual
susceptibility. After stopping vincristine administration, partial or complete clinical
recovery follows which takes several months.
Though some drugs have been found to be effective in managing the symptoms of neuropathy,
yet their full clinical exploitation is limited due to wide spectrum of adverse effects
associated with their clinical use. Moreover, none of the medications, assessed in
randomized controlled studies conducted, has been found to be effective in injury
induced and chemotherapy-induced neuropathic pain [[7]]. Therefore, there has been an urgent need of alternative medicine for managing
neuropathy particularly in injury and chemotherapy-induced neuropathic pain, for which
the best option may be to look back at the traditional medicines.
Ocimum sanctum (L.), (syn, Tulsi) is an indigenous plant commonly found in India and is recommended
in the Ayurveda for the treatment of bronchial asthma, malaria, dysentery, skin diseases,
arthritis, painful eye diseases, chronic fever and insect bite. Experimental reports
have indicated its protective effects against genotoxicants, chemical carcinogens,
ischaemic cerebral injury [[8]], ischaemia-reperfusion and isoproterenol-induced myocardial damage. Moreover, its
anti-convulsant [[9]], hepato-protective, immuno-modulatory, anti-ulcer, anti-diabetic, anti-hypercholesterolaemic,
chemo-protective, nootropic, antitussive, anti-inflammatory, wound healing, anti-tumorigenesis,
anthelmintic, anti-bacterial, anti-giardial [[10]], anti-anxiety [[11]], and anti-stress activities have also been documented. Traditionally, Ocimum sanctum has been used as nerve tonic and to alleviate joint pain, headache and muscular pain
particularly in South India. Recently, from our laboratory it has been documented
that Ocimum sanctum has ameliorative potential in attenuating sciatic nerve transection-induced neuropathic
pain [[12]].
Saponins are important phyto-constituents present in different plants including Ocimum sanctum in which these constitute an important chemical class and include pentacyclic triterpenoids
saponins such as ursolic acid, oleanolic acid [[13],[14]]. Number of studies have shown that saponins exert diverse biological actions such
as anti-hypertensive [[15]], anti-cancer [[16]], anti-convulsant [[17]], anti-diabetic [[18]], anti-amnestic [[19]], hypocholesterolaemic [[20]] and neuroprotective [[21]]. Furthermore, saponins have also been shown to exhibit anti-nociceptive actions
[[22],[23]]; alleviate neuropathic pain in long standing diabetes [[24]] and nerve entrapment induced facial paralysis (Bell’s palsy) [[25]].
The present study was designed to investigate the ameliorative role of Ocimum sanctum in vincristine-induced neuropathy and to further explore the contributory role of
saponins in Ocimum sanctum mediated beneficial effect in neuropathic pain in rats.
Materials and methods
Experimental Animals
Wistar albino rats weighing 180-250 g, maintained on standard laboratory diet (Kisan
Feeds Ltd., Mumbai, India) and having free access to tap water were employed in the
present study. They were housed in the departmental animal house and were exposed
to normal cycle of light and dark. The experimental protocol was approved by the Institutional
Animal Ethics Committee (IAEC) and the care of the animals was carried out as per
the guidelines of the Committee for the Purpose of Control and Supervision of Experiments
on Animals (CPCSEA), Ministry of Environment and Forest, Government of India (Reg.
No- 107/1999/CPCSEA).
Drugs and Chemicals
Vincristine sulfate (Chandra Bhagat Pharma Pvt. Ltd., Mumbai), was dissolved in normal
saline. All the reagents used in the present study were of analytical grade.
Plant material
Fresh leaves of Ocimum sanctum were collected from Patiala and authenticated through Botany Department, Punjabi
University, Patiala. The Plant sample has been kept in Voucher specimen (PUP-039/2008-2009)
at Punjabi university, Patiala. The fresh leaves of Ocimum sanctum were shed dried at room temperature and reduced to coarse powder. The powder was
extracted with mixture of methanol: water (3:1). The solvent was completely removed
at 50°C under reduced pressure. The yield of the extract was 13% (w/w) in terms of
dried starting material. The extract was standardized using HPTLC finger-printing
taking chloroform and methanol (80:20) as mobile phase and using anisaldehyde sulphuric
acid as spraying agent. The bands were detected at 254 nm, 366 nm and under white
light ([Table 1]). The saponin rich fraction was extracted from the concentrated hydro-alcoholic
extract as described earlier [[26],[27]]. Briefly, the hydro-alcoholic extract was decanted by n-hexane followed by extraction
with n-butanol. After three successive extractions with n-butanol, the resulting solutions
were combined and the butanol was completely removed at 50°C under reduced pressure
to collect the residue rich in saponin. The saponins were identified using froth test
and triterpenoid saponins were identified using Lieberman-Burchard test.
Table 1
HPTLC fingerprinting of hydro-alcholic extract of Ocimum sanctum taking chloroform and methanol (80:20) as mobile phase and using anisaldehyde as
spraying agent. The values indicate the Rf values of the separated bands.
|
S. No of Resolving Bands
|
UV 254 nm
|
UV 366
|
Under white light
|
|
1.
|
-
|
-
|
0.44
|
|
2.
|
-
|
-
|
0.60
|
|
3.
|
-
|
-
|
0.71
|
|
4.
|
-
|
-
|
0.78
|
|
5.
|
-
|
-
|
0.85
|
Induction of Neuropathic Pain by Vincristine
Peripheral neuropathy was induced in rats by administration of vincristine sulfate
(50 μg/kg i.p. ) for 10 consecutive days as described previously [[28]].
Behavioral Examination
Paw Cold-Allodynia (Acetone Drop Test)
The cold allodynia was assessed by spraying a 100 μL of acetone onto the planter surface
of the paw, without touching the skin. The duration of withdrawal response was recorded
with an arbitrary minimum value of 0.5 s and a maximum value of 20 s [[29]].
Paw Heat-Hyperalgesia (Hot Plate Test)
The thermal nociceptive threshold, as an index of thermal hyperalgesia, was assessed
by the Eddy’s hot plate, which is an instrument designed by Eddy and co-workers to
assess thermal sensitivity. The plate was pre-heated and maintained at a temperature
of 52.5 ± 2.0°C. The rat was placed on the hot plate and nociceptive threshold, with
respect to licking of the hind paw, was recorded in seconds. The cut-off time of 20
s was maintained [[30]].
Mechanical hyperalgesia: (Pin prick test)
The mechanical hyperalgesia was assessed by the pinprick test as described by Erichsen
and Blackburn-Munro [[31]]. The surface of the injured hind paw was touched with the point of the bent gauge
needle (at 90° to the syringe) at intensity sufficient to produce a reflex withdrawal
response in normal non-operated animals, but at an intensity which was insufficient
to penetrate the skin. The duration of the paw withdrawal was recorded in seconds
with a stopwatch. A cut-off time of 20 s was maintained.
Tail Cold-Hyperalgesia Test (Tail Immersion Test)
The tail cold-hyperalgesia was noted by immersing a terminal part of the tail (1 cm)
in the water, maintained at a temperature of 0-4°C. The tail withdrawal latency was
recorded and a cut-off time of 20 s was maintained [[32]].
Biochemical Estimation
All the groups of animals were sacrificed after 14th day by cervical dislocation and the sciatic nerve was isolated immediately [[30],[33]]. The uniformity among the different nerve samples was maintained by taking the
constant weight of the respective samples. The excised sciatic nerve homogenate (10%
w/v) was prepared with 0.1 M Tris- HCl buffer (pH 7.4). The tubes with homogenate
were kept in ice water for 30 minutes and centrifuged at 4°C (2500 rpm, 10 min). The
supernatant of homogenate was separated, and employed to estimate total protein content,
TBARS, superoxide anion concenteration and total calcium content.
Estimation of the protein content
The protein concentration in the sciatic nerve was estimated according to the method
of Lowry et al., [[34]] using bovine serum albumin as a standard. The absorbance was determined spectrophotometrically
at 750 nm.
Estimation of thio-barbituric acid reactive substances
The estimation of lipid peroxidation in the sciatic nerve was done by measuring the
thio-barbituric acid reactive substances by the method of Okhawa et al. [[35]]. The absorbance was measured spectrophotometrically at 532 nm. The concentration
was expressed in terms of nmol of thio-barbituric acid reactive substances/mg protein.
2.6.3. Estimation of superoxide anion generation
The superoxide anion generation in the sciatic nerve was estimated in terms of measuring
reduced nitroblue tetrazolium (NBT) [[36]]. The absorbance of formazan was determined spectrophotometerically at 540 nm.
Estimation of total calcium
The total calcium levels were estimated in the sciatic nerve as described earlier
[[33],[37]]. Briefly, the sciatic nerve homogenate was mixed with 1 ml of trichloroacetic acid
(4%) in ice cold conditions and centrifuged at 1500 g, for 10 minutes. The clear supernatant
was used for the estimation of total calcium ion by atomic emission spectroscopy at
556 nm.
Experimental Protocol
Nine groups, each group comprising six Wistar albino rats, were employed in the present
study.
Group I: Normal control group
Rats were not subjected to any treatment and were kept for 14 days. The behavioral
tests were employed on different days i.e., day 2nd, 6th, 8th and 14th. All the animals were sacrificed at end of the 14th day and the biochemical analysis was done for estimation of protein content, TBARS,
superoxide anion and total calcium.
Group II: Vincristine control group
Vincristine (50 μg/kg, i.p. ) was administered to normal rats for 10 consecutive days (1-10). The behavioral
tests were assessed starting on days 2nd, 6th, 8th and 14th. At the end of 14th day, the animals were sacrificed and biochemical analysis was done as described in
group I.
Group III: Vehicle in vincristine control group
Rats were administered carboxymethylcellulose suspension (0.5% w/v, p.o. ) 2 h before each vincristine injection, for 14 consecutive days (1-14). The behavioral
tests and biochemical parameters were assessed as mentioned in group I.
Group IV: Hydro-alcoholic extract of Ocimum sanctum per se
The hydro-alcoholic extract of Ocimum sanctum (200 mg/kg p.o. ) was administered to normal rats for 14 consecutive days, starting from the day
one. The behavioral tests and the biochemical parameters were assessed as described
in group I.
Group V: Saponin rich extract of Ocimum sanctum per se
The saponin rich extract of Ocimum sanctum (200 mg/kg p.o. ) was administered to normal rats for 14 consecutive days, starting from the day
one. The behavioral tests and the biochemical parameters were assessed as described
in group I.
Group VI and VII: Hydro-alcoholic extract of Ocimum sanctum (100; 200 mg/kg p.o.) in vincristine control group
The hydro-alcoholic extract of Ocimum sanctum (100; 200 mg/kg p.o. ) was administered for 14 consecutive days, starting from the day one, 2 h prior
to vincristine administration. The behavioral tests and the biochemical parameters
were assessed as described in group I.
Group VIII and IX: Saponin rich fraction of Ocimum sanctum (100; 200 mg/kg p.o.) in vincristine control group
The saponin rich fraction of Ocimum sanctum (100 and 200 mg/kg p.o. ) was administered for 14 consecutive days, starting from the day one, 2 h prior
to vincristine administration. The behavioral tests and the biochemical parameters
were assessed as described in group I.
Statistical Analysis
All the results were expressed as mean ± standard error mean (S.E.M.). The data of
behavioral results was statistically analyzed by two-way ANOVA followed by Bonferonni’s
post test by using Graph pad prism Version-5.0 software. The data of biochemical results
was statistically analyzed by one-way ANOVA followed by Tukey’s multiple range test
by using Sigmastat Version-2.0 software. The p-value < 0.05 was considered to be statistically significant.
Results
Effect of Ocimum sanctum and its Saponin Rich Fraction on Cold Allodynia in Neuropathic Pain
Vincristine administration resulted in the development of cold allodynia as reflected
by an increase in the duration of hind paw withdrawal, when compared to normal control
group. However, pre-treatment with Ocimum sanctum (100 and 200 mg/kg p.o. ) and its saponin rich fraction (100 and 200 mg/kg p.o. ) significantly attenuated vincristine-induced increase in the withdrawal duration
of the hind paw in response to non-noxious cold stimuli. The effect of saponin rich
fraction in attenuating cold allodynia was significantly higher than the hydro-alcoholic
extract at the same dose levels ([Figure 1]). Vehicle administration did not modulate the behaviour in response to non-noxious
cold stimulus in animals subjected to peripheral neuropathy. Per se administration of Ocimum sanctum and its saponin rich fraction also did not produce alterations in the normal rats.
Figure 1 Effect of Ocimum sanctum and its saponin rich fraction on cold allodynia in vincristine-induced neuropathic
pain. Vin.: vincristine; O.s.: Ocimum sanctum ; Sap.: saponin rich extract of Ocimum sanctum. Data were expressed as mean ± S.E.M., n = 6 rats per group. a = p < 0.05 Vs normal
control group, b = p < 0.05 Vs vincristine control group, c = p < 0.05 Vs Ocimum sanctum 100 and 200 mg/kg group, d = p < 0.05 Vs saponin rich fraction 100 mg/kg group.
Effect of Ocimum sanctum and its saponin rich fraction on mechanical hyperalgesia in Neuropathic Pain
Vincristine administration was associated with the development of mechanical hyperalgesia
as reflected by an increase in the hind paw withdrawal duration, when compared to
normal control group. Treatment with Ocimum sanctum (100 and 200 mg/kg p.o. ) and its saponin rich fraction (100 and 200 mg/kg p.o. ) significantly attenuated vincristine-induced increase in withdrawal duration of
the hind paw in response to noxious mechanical stimuli. The effect of saponin rich
fraction in attenuating mechanical hyperalgesia was significantly higher than the
hydro-alcoholic extract at the same dose levels ([Figure 2]). Vehicle administration did not modulate behaviour in response to noxious mechanical
stimulus in animals subjected to peripheral neuropathy. Per se administration of Ocimum sanctum and its saponin rich fraction also did not produce alterations in the normal rats.
Figure 2 Effect of Ocimum sanctum and its saponin rich fraction on mechanical hyperalgesia in vincristine-induced neuropathic
pain. Vin.: vincristine, O.s.: Ocimum sanctum, Sap.: saponin rich extract of Ocimum sanctum. Data were expressed as mean ± S.E.M., n = 6 rats per group. a = p < 0.05 Vs normal
control group, b = p < 0.05 Vs vincristine control group, c = p < 0.05 Vs Ocimum sanctum 100 and 200 mg/kg group, d = p < 0.05 Vs saponin rich fraction 100 mg/kg group.
Effect of Ocimum sanctum and its saponin rich fraction on paw heat and cold tail hyperalgesia in Neuropathic
Pain
Vincristine administration led to the development of paw heat and tail cold hyperalgesia
as reflected by decrease in the withdrawal threshold of the hind paw and tail respectively,
when compared to normal control group. However, treatment with Ocimum sanctum (100 and 200 mg/kg p.o. ) and its saponin rich fraction (100 and 200 mg/kg p.o. ) significantly attenuated vincristine-induced decrease in the withdrawal latency
in response to noxious thermal stimuli. The effect of saponin rich fraction in attenuating
thermal hyperalgesia was significantly higher than the hydro-alcoholic extract at
the same dose levels ([Figures 3] and [4]). Vehicle administration did not modulate behaviour in response to noxious thermal
stimulus in animals subjected to peripheral neuropathy. Per se administration of Ocimum sanctum and its saponin rich fraction also did not produce alterations in the normal rats.
Figure 3 Effect of Ocimum sanctum and its saponin rich fraction on paw heat hyperalgesia in vincristine-induced neuropathic
pain. Vin.: vincristine, O.s.: Ocimum sanctum, Sap.: saponin rich extract of Ocimum sanctum. Data were expressed as mean ± S.E.M., n = 6 rats per group. a = p < 0.05 Vs normal
control group, b = p < 0.05 Vs vincristine control group, c = p < 0.05 Vs Ocimum sanctum 100 and 200 mg/kg group, d = p < 0.05 Vs saponin rich fraction 100 mg/kg group.
Figure 4 Effect of Ocimum sanctum and its saponin rich fraction on tail cold hyperalgesia in vincristine-induced neuropathic
pain. Vin.: vincristine, O.s.: Ocimum sanctum, Sap.: saponin rich extract of Ocimum sanctum. Data were expressed as mean ± S.E.M., n = 6 rats per group. a = p < 0.05 Vs normal
control group, b = p < 0.05 Vs vincristine control group, c = p < 0.05 Vs Ocimum sanctum 100 and 200 mg/kg group.
Effect of Ocimum sanctum and its saponin rich fraction on oxidative stress markers and total calcium
content in Neuropathic Pain
Vincristine administration resulted in an increase in the oxidative stress markers
and total calcium content as reflected by an increase in the tissue thio-barbituric
acid reactive substances, superoxide anion content and total calcium levels, when
compared to normal control group. However, treatment with Ocimum sanctum (100 and 200 mg/kg p.o. ) and its saponin rich fraction (100 and 200 mg/kg p.o. ) significantly attenuated the vincristine-induced increase in oxidative stress markers
and total calcium levels. The effect of saponin rich fraction in attenuating the rise
in the levels of oxidative stress markers and the calcium levels was significantly
higher than the hydro-alcoholic extract at the same dose levels. Vehicle administration
did not modulate alterations in the levels of oxidative stress markers and total calcium
content in animals subjected to peripheral neuropathy. Per se administration of Ocimum sanctum and its saponin rich fraction also did not produce any biochemical alterations in
the normal rats ([Table 2]).
Table 2
Effect of Ocimum sanctum and its saponin rich fraction on thio-barbituric acid reactive substances, superoxide
anion content and total calcium in vincristine-induced neuropathic pain.
|
Groups
|
Doses
|
Total Protein (mg/g of tissue)
|
TBARS (nmol/mg of protein)
|
Superoxide Anion Content (pmol/min/mg of protein)
|
Total Calcium (ppm/mg of protein)
|
|
Normal Control
|
-
|
5.17 ± 0.23
|
5.97 ± 0.26
|
0.15 ± 0.02
|
4.97 ± 0.21
|
|
Vincristine Control
|
-
|
5.36 ± 0.13
|
8.28 ± 0.24a
|
0.79 ± 0.05a
|
32.20 ± 0.18a
|
|
Vehicle in Vincristine Control
|
-
|
5.29 ± 0.17
|
8.24 ± 0.22a
|
0.81 ± 0.03a
|
32.02 ± 0.16 a
|
|
Ocimum sanctum per se
|
200 mg/kg
|
5.21 ± 0.15
|
6.00 ± 0.28
|
0.16 ± 0.01
|
5.09 ± 0.15
|
|
Saponin rich fraction per se
|
200 mg/kg
|
5.30 ± 0.14
|
6.06 ± 0.24
|
0.14 ± 0.02
|
4.92 ± 0.17
|
|
Ocimum sanctum in vincristine control
|
100 mg/kg
|
5.33 ± 0.22
|
7.56 ± 0.16a, b
|
0.56 ± 0.02a, b
|
29.5 ± 0.18a, b
|
|
Ocimum sanctum in vincristine control
|
200 mg/kg
|
5.26 ± 0.16
|
7.52 ± 0.15a, b
|
0.54 ± 0.03a, b
|
29.8 ± 0.20a, b
|
|
Saponin rich fraction in vincristine control
|
100 mg/kg
|
5.35 ± 0.13
|
6.90 ± 0.19a, b, c
|
0.38 ± 0.04a, b, c
|
21.1 ± 0.19a, b, c
|
|
Saponin rich fraction in vincristine control
|
200 mg/kg
|
5.29 ± 0.14
|
6.28 ± 0.21a, b, c, d
|
0.25 ± 0.02a, b, c, d
|
12.2 ± 0.13a, b, c, d
|
Data were expressed as mean ± S.E.M., n = 6 rats per group a = p < 0.05 Vs normal
control group, b = p < 0.05 Vs vincristine control group, c = p < 0.05 Vs Ocimum sanctum 100 and 200 mg/kg group, d = p < 0.05 Vs saponin rich fraction 100 mg/kg group.
Discussion
In the present investigation, vincristine (50 μg/kg, i.p. ) administration for 10 days led to significant development of cold allodynia, mechanical,
tail cold and paw heat hyperalgesia. The observed behavioral alterations in this study
are in consistent with the earlier reports documenting the development of pain symptoms
with vincristine administration [[28],[33]]. Vincristine has been widely employed for the management of number of cancers including
Hodgkin’s disease. However, its clinical application has been limited due to unavoidable
painful sensorimotor neuropathy, observed in about half of the patients on vincristine
treatment. Clinically, the neuropathy is characterized by paresthesias in hand and
feet and the pinprick and thermal senses are more affected than vibration senses.
Binding of vincristine to β-tubulin with subsequent disruption of microtubules has
been documented for its anti-tumor actions and the same is also assumed to produce
neuro-toxicity by axonal degeneration.
However, pretreatment with Ocimum sanctum significantly attenuated vincristine-induced alterations in pain perception in response
to noxious as well as non-noxious stimuli, suggesting that Ocimum sanctum may be employed to limit the painful symptoms associated with chemotherapy treatment.
Traditionally, Ocimum sanctum has been used as a nerve tonic to alleviate disorders related to nerves. Recently,
it has been reported from our laboratory that Ocimum sanctum attenuates the neuropathic pain in sciatic nerve transection model [[12]].
Ocimum sanctum is a rich source of a number of saponins and the most important of them are ursolic
acid and oleanolic acid. These saponins have been reported to possess beneficial effects
in number of disorders such as in amnesia [[38]], hypertension [[39]], myocardial ischemia [[40]], and cancer [[41]]. Furthermore, the saponins have also shown the beneficial effects in relieving
nociceptive pain [[22],[23]] as well as neuropathic pain in diabetes [[24]] and facial paralysis (Bell’s palsy) due to nerve entrapment [[25]]. Therefore, to explore the chemical class of Ocimum sanctum responsible of its beneficial effect its saponin rich fraction was evaluated in neuropathic
pain. In the present investigation, pre-treatment with the saponin rich fraction of
Ocimum sanctum attenuated vincristine-induced behavioral alterations in neuropathic pain. Therefore,
it may be proposed that saponins are the principal components responsible for the
noted beneficial effects of Ocimum sanctum in neuropathic pain.
Furthermore, in this study vincristine administration was associated with the rise
in the oxidative stress (rise in thio-barbituric acid reactive substances and superoxide
anion content) and total calcium content. It has also been documented that oxidative
stress and an increase in calcium levels play a critical role in chemotherapy associated
neuropathic pain including vincristine [[28],[33],[42]]. However, treatment with Ocimum sanctum and its saponin rich fraction attenuated vincristine associated increase in oxidative
stress and calcium levels. Ocimum sanctum has a well documented antioxidant effect [[10],[43]] and also decreases the calcium levels [[12]].
Free radicals have been well documented to increase calcium levels [[44],[45]]. Therefore, the observed decrease in calcium levels with Ocimum sanctum may possibly be attributed to its antioxidant effects. However, it may also be possible
that direct action of Ocimum sanctum is responsible for the observed decrease in the calcium levels. Therefore, the observed
decrease in calcium levels due to Ocimum sanctum may be either due to direct action or secondary to decrease in oxidative stress.
However, data of the present study is still insufficient to elaborate the precise
mechanism of Ocimum sanctum mediated decrease in calcium levels. Furthermore, saponins have also been reported
to decrease oxidative stress [[46]] and calcium levels [[47],[48],[49]]. Based on these, it may be proposed that Ocimum sanctum has potential in ameliorating the painful symptoms in vincristine-induced peripheral
neuropathy and saponins may be the principal chemical class responsible for its beneficial
effect in neuropathic pain. Furthermore, the pain relieving effects of Ocimum sanctum and its saponin rich fraction may be due to attenuation of nerve injury inciting
agent-induced increased levels of calcium and free radicals.
Competing interests
The authors declare that they have no competing interests.
Authors’ contributions
GK carried out experimental studies including induction of neuropathy, behavioral
and biochemical testing. ASJ carried out data analysis including the statistical analysis
and participated in critical intellectual discussion and designing of the experiments.
NS conceived the idea, coordinated the study, carried our data interpretation and
drafted the manuscript. All authors read and approved the final manuscript.
Cite this article as: Kaur et al.: Exploring the potential effect of Ocimum sanctum in vincristine-induced neuropathic
pain in rats. Journal of Brachial Plexus and Peripheral Nerve Injury 2010 5:3.
