[Indian Journal of Experimental Biology (1993): (31), 435]

Chronic administration of ethanol (2-5 g/kg p.o.) on days 1 to 6 and its withdrawal produced anxiogenic reaction in mice and rats as assessed on the elevated plus-maze. Daily administration of Mentat (100-mg/kg) prior to ethanol intoxication for 6 days prevented withdrawal-induced anxiety in both rats and mice. However, the acute administration of a single dose of Mentat to animals withdrawn from ethanol i.e. On the 7th day, elicited a significant anxiogenic response. Ethanol withdrawal also sensitized the convulsogenicreaction to pentylenetetrazole (PTZ). A non-convulsive dose (40 or 60 mg/kg) of PTZ produced full-blown convulsions and increased mortality in ethanol-withdrawn rats and mice, respectively. Both acute and chronic administration of Mentat (100 mg/kg) exhibited significant protection against ethanol withdrawal-induced reduction of PTZ threshold in rats and mice. The results suggest the usefulness of this safe herbal psychotropic preparation in the management of ethanol withdrawal reactions. INTRODUCTION Physical dependence on ethanol is defined by the presence of an ethanol is withdrawal syndrome that becomes apparent following cessation of ethanol intake and elimination of ethanol from the system. The withdrawal syndrome, well characterised in humans and in animal models, consists of an early reaction (tremor, diaphoresis, hallucinations, convulsions) and a delayed one (delirium tremens, increased autonomic activity, profound sweating, and profound disorientation). Alcoholism and withdrawal of chronic alcohol intake are grave social and medical problems. There is no single drug therapy that helps patients in overcoming alcoholism. Mentat (BR-16A), a herbal psychotropic preparation, contains the following main indigenous ingredients (besides others) reputed in the ancient system of Ayurvedic medicine to be useful in the management of nervous disorders: Brahmi (Hydrocotyl asiatica), Shatavari (Asparagus racemosus), Shatavari (Asparagus racemosus), Bach (Acorus calamus), Ashwagandha (Withania somnifera), Giloe (Tinospora cordifolia), Amla (Emblica officianlis), Shankhapushpi (Evolulus alsinoides) and Triphala. Preliminary toxicity studies have shown it to be a safe preparation and no adverse effect ensued its chronic use (unpublished data). Recent studies have demonstrated the effectiveness of Mentat in preventing the development of tolerance to and dependence on morphine in mice. The present study has been undertaken to evaluate the de-addiction potential of this herbal preparation against alcohol. Alcohol withdrawal reactions are determined as reduction in pentylenetetrazole (PTZ) threshold (convulsions) and increase in anxiety response as measured on elevated plus-maze. MATERIALS AND METHODS The effectiveness of Mentat in suppressing the symptoms of ethanol withdrawal was investigated in rats and mice. Balb'c strain, albino mice weighing 20-25 g and porton rats weighing 150-200 g of either sex, bred in the Central Animal House facility of the University were used. The animals were housed under standard light/dark conditions with food and water ad libitum. The experiments were performed between 0900 and 1700 hrs. Treatment schedule In acute studies, animals received ethanol (2 g/kg of 10% ethanol in mice and 5 g/kg of 20% ethanol in rats), intragastrically. After 30 min, its effect on elevated plus-maze was studied. In chronic studies, mice received 2 g/kg of 10% w/v ethanol, intragastrically, twice a day on the 1st day and once daily on successive days for a total of 6 days. In rats, 5 g/kg of ethanol (20% w/v) was administered intragastrically, three times a day for 6 days. On the 7 day, i.e. 24 hr after the last dose of ethanol, rats/mice were tested for withdrawal reactions. The other treatment groups included (pretreatment: treatment): (i) saline: saline (ii) saline: ethanol, and (iii) Mentat: (100 mg/kg): ethanol. Control experiments were performed on day 7 to determine whether Mentat prevented the development of withdrawal syndrome or it simply altered the behavioural expression of the withdrawal symptoms. On this day, the treatments were reversed so that the animals that had received Mentat, followed 30 min later, by ethanol on days 1 through 6, were challenged with saline. Similarly, the animals which received saline followed 30 min later by ethanol, received only Mentat. The group chronically treated with saline received the same (saline only). The withdrawal reaction was assessed by studying the anxiogenic reaction on elevated plus-maze or decreased threshold to pentylenetetrazole (PTZ: convulsive response to an otherwise nonconvulsive dose in naïve animals). Elevated plus-maze: measurement of anxiety The elevated plus-maze used for rats and mice was the same as described earlier. Briefly, the apparatus for mice consisted of two open arms (16 x 5 cm) and two enclosed arms (16 x 5 x 12 cm), and for rats it consisted of two open arms (50 x 10 cm) and two enclosed arms (50 x 10 x 40 cm). The maze was elevated to a height of 25 cm for mice and 50 cm for rats. During the 5 min test session the following parameters were noted: (I) number of entries the animal made in open and enclosed arms (ii) the total time spent in each arm, and (iii) choice of open/enclosed arm as first entry. Animals were put individually at the centre of the plus-maze facing an open arm at the beginning of the test. An anxiogenic response was defined as decreased number of entries and time spent in open arm. There was reduction in percent preference for the open arm in anxiogenic animals. PTZ threshold The onset of body jerks, clonic convulsions followed by tonic convulsions and death were recorded following PTZ challenge in naïve and ethanol-withdrawn animals. Each animal was observed individually for 2 hr for acute response. Reduction in the dose of PTZ to produce full blown convulsions in ethanol-withdrawn animals was considered as withdrawal-induced reduction in the convulsive threshold. The protective effect of Mentat following acute and chronic treatment was noted in rats and mice. Drugs The drugs used were Mentat (The Himalaya Drug Co., Bombay), pentylentetrazole (Sigma, USA) and ethanol (Bengal Chemicals & Pharmaceuticals Ltd., Calcutta). Pentylenetetrazole and ethanol were prepared in distilled water. Mentat (100 mg/kg) powder was suspended uniformly in distilled water. Ethanol (2g/kg of 10% w/v in mice and 5 g/kg of 20% w/v in rats) and Mentat were administered orally, while PTZ (40-80 mg/kg) was injected i. p. All the drugs except ethanol were administered in a constant volume of 1 ml/100 g of body weight. Pentylenetetrazole was administered 24 hr after the last dose of ethanol (withdrawal animals) and Mentat was given 30 min prior to ethanol. Statistical analysis The date expressed as mean ± SE were analyzed by Student's 't' test. Probability levels <5% were considered significant. RESULTS Effect of Mentat on ethanol withdrawal-induced anxiety Acute administration of ethanol (2 g/kg; 10% w/v) in mice produced a significant increase in the duration in open arms as compared with the vehicle-treated control mice (Table 1). Similarly, in rats ethanol (5 g/kg; 20% w/v) produced a significant decrease in the number of entries in closed arms and increase in the time spent in open arms (Table 2). Percent preference for closed arm entry was also reduced following acute treatment with ethanol as compared with the vehicle-treated group in both rats and mice. Table 1: Effect of Mentat on ethanol (EtOH) withdrawal-induced anxiety in mice (Values are mean ± SE)