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Paper   IPM / Cognitive Sciences / 11536
School of Cognitive Sciences
  Title:   Influence of morphine- or apomorphine-induced sensitization on histamine state-dependent learning in the step-down passive avoidance test
  Author(s): 
1.  Mohammad Reza Zarrindast
2.  Azita Khalilzadeh
3.  Nazanin Malekmohammadi
4.  Soheila Fazli-Tabari
  Status:   Published
  Journal: BEHAV BRAIN RES
  Vol.:  171
  Year:  2006
  Pages:   50-55
  Supported by:  IPM
  Abstract:
Effects of morphine- or apomorphine-induced sensitization on histamine state-dependent memory of passive avoidance task were examined in mice. Pre-training intracerebroventricular (i.c.v.) administration of histamine (20 g/mouse) decreased the learning of a one-trial passive avoidance task. Pre-test administration of histamine (10 and 20 g/mouse) reversed amnesia induced by pre-training of histamine, with maximum response at 20 g/mouse. Pre-training histamine-induced amnesia was also reversed in morphine- or apomorphine-sensitized mice that had previously received once daily injections of morphine (20 and 30 mg/kg) or apomorphine (0.5 and 1 mg/kg) for 3 days. The reversion of histamine-induced amnesia in morphine-sensitized mice was decreased by once daily administration of naloxone (0.5 and 1 mg/kg), SCH 23390 (0.05 and 0.1 mg/kg) or sulpiride (25, 50 and 100 mg/kg) prior to injection of morphine (30 mg/kg/day, 3 days). Furthermore, once daily administration of sulpiride (50and 100 mg/kg) but not SCH 23390 (0.01, 0.05 and 0.1 mg/kg) prior to apomorphine (1 mg/kg, for 3 days) decreased the reversion of pre-training histamine-induced amnesia by apomorphine. The results suggest that apomorphine or morphine sensitization affects the impairment of memory induced by histamine and thus it is postulated that opioid and dopamine receptors may play an important role in this effect.

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