Indian Journal of Pain

ORIGINAL ARTICLE
Year
: 2015  |  Volume : 29  |  Issue : 3  |  Page : 150--154

Protective effect of Rubia cordifolia in paclitaxel-induced neuropathic pain in experimental animals


Chaitali Diwane, Rupali Patil, Prashant Vyavahare, Rajendra Bhambar 
 Department of Pharmacology, MGV's Pharmacy College, Nashik, Maharashtra, India

Correspondence Address:
Chaitali Diwane
MGV«SQ»s Pharmacy College, Nashik - 422 003, Maharashtra
India

Abstract

Background: Neuropathic pain is a pain initiated or caused by a primary lesion or dysfunction of the nervous system. Material and Methods: In this study, we evaluated the effect of alcoholic extract of roots and rhizomes of Rubia cordifolia on the development and expression of neuropathic pain induced by paclitaxel in sciatic nerve ligated rats. A peripheral mononeuropathy was produced in adult Wistar rats by placing loosely constrictive ligatures around the common sciatic nerve. The postoperative behavior of these rats indicated that hyperalgesia, allodynia, and spontaneous pain were produced. Treatment with paclitaxel (2 mg/kg i.p. on 7 th , 10 th , and 21 st day) produced long-lasting (2-3 weeks) heat hyperalgesia and cold allodynia in rats. Conclusion: Co-administration of R. cordifolia extract for 21 days significantly decreased pain indicating its usefulness in neuropathic pain.



How to cite this article:
Diwane C, Patil R, Vyavahare P, Bhambar R. Protective effect of Rubia cordifolia in paclitaxel-induced neuropathic pain in experimental animals.Indian J Pain 2015;29:150-154


How to cite this URL:
Diwane C, Patil R, Vyavahare P, Bhambar R. Protective effect of Rubia cordifolia in paclitaxel-induced neuropathic pain in experimental animals. Indian J Pain [serial online] 2015 [cited 2023 Apr 2 ];29:150-154
Available from: https://www.indianjpain.org/text.asp?2015/29/3/150/165833


Full Text

 Introduction



Neuropathic pain can develop after nerve injury when deleterious changes occur in injured neurons and along nociceptive and descending modulatory pathways in the central nervous system. [1] The myriad neurotransmitters and other substances involved in the development and maintenance of neuropathic pain also play a part in other neurobiological disorders. This might partly explain the high comorbidity rates for chronic pain, sleep disorders, and psychological conditions such as depression and effectiveness of drugs that are useful in one condition may benefit others. [2] Neuropathic pain can be distinguished from nonneuropathic pain by two factors. First, in neuropathic pain there is no transduction (conversion of a nociceptive stimulus into an electrical impulse). Second, the prognosis is worse; injury to major nerves is more likely than injury to nonnervous tissue to result in chronic pain. However, because of the considerable overlap between neuropathic and nociceptive pain in terms of mechanisms and treatment modalities it might be more constructive to view these entities as different points on the same continuum. [3]

Paclitaxel is a widely used anticancer agent for the treatment of ovarian, breast, lung, and neck cancer. Paclitaxel is known for two main side effects, myelosuppression, and peripheral sensory neurotoxicity. These side effects often necessitate the use of suboptimal doses. In rodents, administration of paclitaxel causes neuropathic pain that is comprised of thermal hyperalgesia and mechanical allodynia, which can be reversed by different analgesic agents. [4]

Rubia cordifolia Linn. (Rubiaceae) also known as "manjistha" is an important medicinal plant. It possesses antitumor, [5] antistress, antihyperglycemic, [6] antimicrobial, [7] hepatoprotective, [8] and radio protective [9] activities. This plant has also been listed officially as herbal medicine in the Chinese Pharmacopoeia for the treatment of arthritis, dysmenorrhea, hematorrhea, and hemostasis, which are free radical related diseases. It also shows in vitro antioxidant activity and anticholinergic activity. [10]

R. cordifolia is known to possess analgesic [11] and anticancer activities, [12]. rubiadin isolated from this plant shows antioxidant activity. [13] Anthraquinones isolated from this plant are under clinical trials for anticancer activity. Hence, in this study, we evaluated the effect of alcoholic extract of roots and rhizomes of R. cordifolia on paclitaxel-induced neuropathic pain in sciatic nerve ligated experimental animals.

 Materials and Methods



Animals

Adult albino Wistar rats (100-150 g) of either sex were used for this study. The animals were housed at 24 ± 2°C and relative humidity 55 ± 5 with 12:12 h light and dark cycle. They had a free access to food and water ad libitum. The animals were acclimatized for a period of 7 days before the study. The experimental protocol was approved by the Institutional Animal Ethics Committee of MGV's Pharmacy College, Nashik. (Approval No: MGV/PC/CPCSEA/XXX/01/2015).

Drugs and treatment schedule

Paclitaxel was obtained from Emcure Pharmaceuticals Ltd, Pune, India. Aspirin (Research Lab, Mumbai), and pentazocine (Fortwin, Ranbaxy) were used as reference drug for antinociceptive activity. All the chemicals were of analytical grade, and chemicals required for sensitive biochemical assays were obtained from Merck.

Plant material

Roots and rhizomes of R. cordifolia Linn. (Rubiaceae) were obtained from Aushadhi Bhavan, Ayurved Seva Sangh, Nashik, Maharashtra. The plant material was identified and authenticated by Prof. S. C. Pal, Head of Pharmacognosy, Department of MVP Samaj's College of Pharmacy, Nashik (Voucher No. MVP/2009/12).

Preparation of extract

The coarse dried powder of roots and rhizomes of R. cordifolia (200 g) was defatted with petroleum ether (60-80°C), and then the marc was successively extracted with ethanol using Soxhlet apparatus. The alcoholic extract of Rubia cordifolia (AERC) was concentrated on water bath (yield: 11% w/w) and stored in airtight container, in a dry place.

Phytochemical analysis

Standard phytochemical screening tests were carried out for various constituents of the AERC according to the methods of Trease and Evans (1983). Observations were carried out for color change and precipitation. It revealed the presence of saponins, tannins, alkaloids, glycosides, flavonoids, and essential oils.

Sciatic nerve surgery

Male Wistar rats were anesthetized with sodium pentobarbital (40 mg/kg, i.p.; supplemented as necessary). The common sciatic nerve was exposed the level of the middle of the thigh by blunt dissection through biceps femoris. Proximal to the sciatica trifurcation about 7 mm of nerve was freed of adhering tissue, and four ligatures (4.0 chromic gut) were tied loosely around it with about 1 mm spacing. The length of nerve thus affected was 4-5 mm long. Great care was taken to tie the ligatures such that the diameter of the nerve was seen to be just barely constricted when viewed with ×40. The desired degree of constriction retarded but did not arrest, circulation through the superficial epineurial vasculature and sometimes produced a small, brief twitch in the muscle surrounding the exposure. The incision was closed in layers. [14] These animals were used to study the effect of AERC on paclitaxel-induced neuropathic pain in cold allodynia and hot plate method.

Treatment schedule

Male Wistar rats (n = 5) were divided into six groups; Group 1 received distilled water (5 ml/kg, p.o.). Group 2 received paclitaxel (2 mg/kg, i.p.) per se on 7 th , 10 th , and 21 st day. Group 3, 4, and 5 received AERC (100, 200, 400 mg/kg), respectively, for 21 days along with paclitaxel (2 mg/kg, i.p.) on 7 th , 10 th , and 21 st day. Group 6 received pentazocine (17.5 mg/kg, i.p. for 21 days) and paclitaxel (2 mg/kg, i.p.) on 7 th , 10 th and 21 st day.

Cold allodynia

One day after sciatic nerve ligation animals received AERC (100, 200, and 400 mg/kg, p.o.) and pentazocine (17.5 mg/kg, i.p.). One hour after administration of AERC and 30 min after administration of pentazocine and paclitaxel was administered as an inducer. The number of paw licking was measured at 60, 120, and 180 min interval after paclitaxel by keeping the animal on the ice slab. [14]

Hot plate method

One day after sciatic nerve ligation animals received AERC (100, 200, and 400 mg/kg, p.o.) and pentazocine (17.5 mg/kg, i.p.). One hour after administration of AERC and 30 min after administration of pentazocine and paclitaxel was administered as an inducer. Animals were placed individually on a hot plate maintained at a temperature of 55 ± 0.5°C. The latency to lick the paw was the reaction time. Hyperalgesia was assessed by measuring the latency to lick the paw at 60, 120, and 180 min after administration of paclitaxel. The cut off time was set at 20 s to avoid damage to the skin. [15]

Statistical analysis

All the data were shown as mean ± standard error of the mean. Statistical analysis was performed with one-way ANOVA followed by Dunnett's test. Differences of *P < 0.05, **P < 0.01, ***P < 0.0001 was considered as statistically significant.

 Discussion



Large numbers of herbal drugs are reported to have excellent medicinal value and are in use for the treatment of several ailments. Pain is associated with various clinical conditions such as autoimmune disease (e.g., multiple sclerosis), metabolic diseases (e.g., diabetic neuropathy), infection (e.g., shingles and the sequel, postherpetic neuralgia), vascular disease (stroke), trauma, and cancer. A rule without apparent exception is that the lesion leading to pain must directly involve the nociceptive pathways. [1] Accordingly, for example, lesions of the medial lemniscus system (e.g., dorsal columns) do not induce pain. [16]

Pain is a direct response to an untoward event associated with tissue damage such as injury, inflammation, or cancer. [17] Analgesics relieve pain as a symptom, without affecting its cause. [18] Most of the drugs used at present for analgesic effect are synthetic in nature, prolonged use of which causes several side and toxic effect including respiratory depression, constipation, kidney damage, physical dependence, as well as gastric irritation. Furthermore, acute and chronic administration of drugs such as aspirin induces anemia associated with leukocytosis. [19] Therefore, naturally originated agents with very little side effects are required to substitute chemical therapeutics of acute and chronic pain. Neuropathic pain related to chemotherapeutic agents is often resistant to standard analgesics.

Paclitaxel is a widely used anticancer agent for the treatment of ovarian, breast, lung, head, and neck cancer. There are two well-documented side effects of this treatment: Myelosuppression and peripheral sensory neurotoxicity. These side effects often necessitate the use of suboptimal doses (dose-limiting therapy) or even a complete suspension of treatment. In patients, paclitaxel-induced peripheral neuropathy is characterized by degeneration of sensory axons and is clinically manifested as numbness, pain, and thermo-hyperesthesia in hands and feet. [20]

Thousands of herbal and traditional compounds are being screened worldwide to validate their use as anticancer drugs; R. cordifolia is one of them. It contains substantial amounts of anthraquinones, especially in the roots which are responsible for the antitumor activity. The plant contains substantial amounts of anthraquinones, especially in the roots, which is responsible for its pharmacological activity. Cancer is a dreadful disease, and any practical solution in combating this disease is of paramount importance to public health. An integrated approach is needed to manage cancer using the growing body of knowledge gained through scientific developments. R. cordifolia can be a source of potent pharmacophore for the treatment of disease such as cancer. Thus, cancer patients who already got crippled with this disease, who are further burdened by drug-induced toxic side effects, have now turned to seek help from the complementary and alternative medicine hoping for a better cure. [21]

The extract of R. cordifolia obtained by successive solvent extraction with ethanol was subjected to preliminary phytochemical analysis, which revealed the presence of saponins, tannins, alkaloids, glycosides, flavonoids, and essential oils. In the present study, we investigated the influence of an ethanolic extract of roots and rhizomes of R. cordifolia on paclitaxel-induced neuropathic pain in sciatic nerve ligated rats. The study was attributed to study the possible central antinociceptive activity of AERC in neuropathic pain.

Studies show that treatment with paclitaxel (2 mg/kg) produces long lasting heat hyperalgesia and cold allodynia in rats by sciatic nerve surgery. [4] In [Figure 1], [Figure 2], [Figure 3] the present study demonstrated that AERC significantly decreased withdrawal latency in cold allodynia method as compared to paclitaxel per se and in [Figure 4], [Figure 5], [Figure 6] the study demonstrated that AERC significantly decreased withdrawal latency in the hot plate method as compared to paclitaxel per se. AERC and pentazocine produced a significant analgesia in paclitaxel-induced neuropathic pain by sciatic nerve surgery.{Figure 1}{Figure 2}{Figure 3}{Figure 4}{Figure 5}{Figure 6}

Anticonvulsants by potentiating gamma-aminobutyric acid (GABA) transmission, reduction of glutamate-mediated excitatory transmission, and blockade of voltage-activated ion channels show adjuvantive analgesic action. [22] R. cordifolia is known to show anticonvulasant activity. [10] AERC increased brain content of GABA in a dose-dependent manner. [23]

Hence, this study concludes that AERC exhibits significant inhibition of paclitaxel-induced neuropathic pain in sciatic nerve ligated animals may be due to the involvement of GABA or antioxidant mechanism.

 Conclusion



This study concludes that AERC significantly inhibited paclitaxel-induced neuropathic pain after sciatic nerve ligation. The combination of R. cordifolia with paclitaxel may help to reduce side effects and a dose of paclitaxel.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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