Effect of American Ginseng Extract on Formalin-Induced Nociception in Mice

American Journal of Chinese Medicine, Wntr, 2001 by J.C. Yang, C.S. Pang, S.F. Tsang, K.F. Ng

(Accepted for publication November 2, 2000)

Abstract: Twenty-three ICR mice were force fed orally with American ginseng extract, Panax quinquefolius, (Cold FX[R]) for 4 days. Another 20 mice were fed with water as placebo in a similar fashion. Formalin tests which yield typically two phases of pain behavior were done in both groups. Although there was no difference in the first phase between groups, mice treated with Cold FX[R] spent significantly less time in licking and biting of the injured paws in the second phase. The data indicate that American ginseng may have analgesic effect in this chronic pain model.

Herbal medicines are increasingly used by the general population (Austin, 1998). Ginseng is one of the most popular herbs. However, evidences for its claimed efficacy are contradictory (Vogler et al., 1999). This is due to the variability in its constituents (Attele et al., 1999).

Cold FX[R] is American Ginseng extract marked by CV Technologies (Edmonton, Canada). The company guaranteed batch to batch chemical consistency by high performance liquid chromatograph and biological reliability by lymphocyte proliferation assay (Shan, 1999). Hence, it is a consistent product of American ginseng in spite of unknown chemical structures.

Formalin test (Dubuisson et al., 1977) induces nociception by injecting formaldehyde under the skin of a mouse's paw. This results in two phases of pain behavior manifest as frequent biting and licking of the injured paw. The first phase occurs within 5 min after the injection. These rapid rises and falls of nociception are mediated through C and A [Delta] fibers (Puig et al., 1996). It reflects the sensation of acute tissue damage. After a quiescent period which indicates the immediate nociception stimuli have subsided, pain behavior in the second phase could be observed again. Thus, the second phase is more closely associated with the chronic pain model. Stimuli of the first phase are transmitted through the lateral spinothalamic tract, whereas stimuli in the second phase are through the medial spino-thalamic tract (Melzack, 1990).

In the management of clinical chronic pain, analgesics alone are often not enough. Even with multi-disciplinary treatment, the results have not always been satisfactory. This is one of the main reasons many chronic pain patients seek alternative therapy (Nayak et al., 1999). Ginseng has been widely used as an adjuvant for this purpose. It is considered to be a tonic for general health and it is believed that improvement of fitness would raise the pain threshold. One of the extracts, Ginsenoside Rf, has been reported to produce antinociception in mice (Mogil et al., 1998). However, Ginsenoside Rf presents only as a trace component in Korean ginseng (Parik et al., 1982). It could be quite different from American ginseng. Various ginseng extracts can be of completely different composition (Cui et al., 1994). In that study, the Ginsenoside Rf was given by injection (Mogil et al., 1998) which is not a common route for the intake of herbs. Furthermore, the complexity of ginseng extracts suggests that gensenoside Rf might not be the only active compound.

The present study is to investigate whether the American ginseng preparation (Cold FX[R]) has an antinociceptive effect in mice given orally.

Methods

Materials

Cold FX[R], the extract of concentrated active ingredients of ginseng was supplied by C.V. Technologies, Edmonton, Canada. The specifications for Cold FX[R] are presented in Table 1.

Table 1. Specification for Cold FX[R]

Chemical Analyses

Total Ginsenosides (%)           < 3.0

Individual Ginsenosides (%)
  Rb1                            0.2- 1.4
  Rc                             0.08-0.5
  Rc                             0.07-0.7
  Rd                             0.08-0.6
  Rg1                            < 0.02

Component sugars (molar ratio)
  Rhamnose                       > 0.8
  Galatsuronic acid              > 9
  Glucose                        > 40
  Galactose                      > 7
  Arabinose                      > 8

Protein content (%)              > 4

Total saccharides (g/:00g)       > 40

Microbiological Analyses

Standard plate count (CFU/g)     < 100,000

Coliforms (CFU/g)                < 100

E. Coli (CFU/g)                  negative

Yeast and mold (CFU/g)           < 100

Salmonella                       0 (zero tolerance)

Biological Activity

Lymphocyte proliferation         > 200% with sample
(% of control)                   concentration of 100 [Micro]g/ml

Courtesy of CV Technologies, Edmonton, Canada

Animals

Thirty to 40 day old young male ICR mice supplied by the Animal Unit of the University of Hong Kong were housed at room temperature of 23 [ or ] 1 [degrees] C for at least 1 week before the experiment. They were fed with food and water ad libitum.

After a 1-week adaptation period, the mice were weighed. They were force fed once daily with 0.3 ml of 150 mg/kg of Cold FX[R] dissolved in water for 4 days. The choice of dosage and treatment period were based on the recommendation printed on the pamphlet to be taken by humans. The placebo group were fed with 0.3 ml water. A bent blunted 20-gauge needle connected to a 1 ml syringe was used for the intragastric administration.

All tests were conducted under the guidelines of the International Association for the Study of Pain (Zimmermann, 1983).

Formalin Tests

A formalin test for nociception was performed on day 4. It was done 2 hr after the last forced feeding. All tests were performed from 1 pm to 3 pm to control for pain threshold variation due to circadian rhythm.