title: The effect of vitamin C on morphine self-administration in rats.
abstract: BACKGROUND
  Recent studies have shown that addiction may be caused by abnormality of neurotransmission in the brain. Two neurotransmitters that involve into morphine addiction are dopamine and glutamate. The glutamatergic and dopaminergic systems are also involved in morphine tolerance and morphine withdrawal syndrome signs. Ascorbic acid (AA), as the antioxidant releases from the glutamatergic neurons, modulates the action of the dopamine and glutamate systems. In this study, the effect of AA on morphine self-administration and morphine withdrawal symptoms has been investigated.
  
  
  METHODS
  Male Wistar rats (250 - 300g) were anesthetized with ketamine (11%) and xailazine (15%). The cannula was inserted into the right jugular vein, and it was fixed subcutaneously on the skull. After surgery the animals were placed in individual home cages, and they were allowed to recover from the operation for five days, before the test. The animals were subjected to self-administration morphine for12 consecutive days, two-hour/sessions. The number of infusions and number of active and passive lever pressings were recorded.
  
  
  RESULTS
  An intra peritoneal injection of Ascorbic acid (AA) (400 mg/kg, i.p.), 30 minutes before morphine self-administration, produced a significant decrease in 12 days self-administration of morphine and withdrawal syndrome signs (P < 0.05). The morphine withdrawal signs (MWS) were recorded after naloxone precipitation, which decreased significantly with the injection of AA (400,700mg/kg), (<0.05). The number of self-infusions and the number of active lever pressings had significantly decreased after AA injection (P < 0.05).
  
  
  CONCLUSIONS
  The chronic administration of AA may prevent the development of tolerance and physical dependence on morphine self-administration via the glutamatergic system.
authors.affiliation: Department of Biology, Isfahan University, Isfahan, Iran.
authors.forename: Mahboobeh
authors.initials: M
authors.lastname: Talkhooncheh
authors.affiliation: Department of Physiology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Hojjat Allah
authors.initials: HA
authors.lastname: Alaei
authors.affiliation: Department of Physiology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Effat
authors.initials: E
authors.lastname: Ramshini
authors.affiliation: Department of Physiology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Somaei
authors.initials: S
authors.lastname: Shahidani
keywords: Ascorbic acid; morphine; rat; self-administration