Title

 

Authors

C. Mannucci¹, M. Navarra^2,3, E. Calzavara¹, A. Pieratti¹, A.P. Caputi^1,3, G. Calapai^1
 
1Department of Clinical and Experimental Medicine and Pharmacology, Section of Pharmacology, School of Medicine, University of Messina, Italy
²Pharmaco-Biological Department, University of Messina, Italy
³IRCCS Centro Neurolesi “Bonino-Pulejo”, University of Messina

 

Abstract

Rhodiola rosea L., is the most investigated species of the genus Rhodiola. It grows at elevated altitudes in the Arctic and in mountainous regions throughout Europe and Asia, where it is also known as “golden root” or “arctic root”. The roots have been used for centuries in the folk medicine to stimulate the nervous system, enhance physical and mental performance, improve resistance to high altitude sickness and to treat fatigue, psychological stress and depression (Panossian, 2003; Panossian and Wagner, 2005). Many studies have provided scientific evidence that administration of Rhodiola rosea extract elicits antidepressant activity (Darbinyan et al., 2007; Panossian et al., 2008), but the mechanism of action of Rhodiola rosea still remains unclear. Scientific proof of association between depression and tobacco smoking exists (Carton et al., 2002; Dierker et al., 2002). It has been observed that administration of nicotine from transdermal patches can exert an antidepressant-like activity in nonsmokers (Salin-Pascual et al., 1996) and evidence that nicotine reduces symptoms of depression emerges also from animal models. A further link between smoking and mood disorders is represented by the evidence that nicotine cessation induces depressive-like symptoms in smokers and may elicit a state in which smokers are more sensitive to the adverse effects of stress (Balfour and Ridley, 2000). On this basis, we investigated the possible beneficial effects of Rhodiola rosea on nicotine withdrawal signs. Nicotine dependence was induced in Sprague-Dawley rats weighing 225 g by subcutaneous nicotine injection (2mg/kg in 1 ml of saline, four times daily) for 14 consecutive days. A group of animals treated with 1 ml of saline (four times daily) for 14 consecutive days served as controls. All animals were evaluated for behavioural (locomotor activity, abstinence signs, marble burying test) and biochemical parameters (diencephalic serotonin metabolism and 5-HT_1A expression), 24 after nicotine withdrawal. A group of nicotine-dependent rats were treated with R. rosea extract and/or with selective serotonin receptor 5-1A (5-HT_1A) antagonist WAY 100635 (WAY) (1 mg/kg) after the last nicotine injection. R. rosea reduced in a significant way nicotine abstinence behaviour in dependent rats. This effect were antagonized by WAY administration. Moreover we observed a  significant increase of diencephalic serotonin content in nicotine dependent rats, treated with R. rosea, with a concomitant significant increase of serotonin receptor 5-HT_1A. Results suggest the involvement of serotonin in beneficial effects of R. rosea on suffering produced by nicotine withdrawal in dependent rats.
 
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