Introduction: benzodiazepine drugs notably have an anxiolytic and amnesic features, while β-carbolines as their receptors inverse agonists show effects of anxiety and increasing learning features. The aim of present study was to investigate the effects of Norharmane on memory retention of Alzheimer model rats induced with streptozotocin (STZ) in passive avoidance learning.
 Materials & methods: 48 male wistar rats were divided into: control, STZ, STZ+ alcohol and STZ+ norharmane groups. STZ was injected bilaterally into lateral ventricles for induction of AD, (3 mg/kg, i.c.v, 10 μl on each side). Two weeks later, all rats were trained in the passive avoidance device (50Hz, 1mA, for 3sec). Alcohol (0.2ml) or Norharmane (1, 2, 4 mg/kg, Intraperitoneal) were injected to rats after training immediately. Retention test was done 48 hours later. The time to take the animal enters the dark chamber device measured as a standard memory.
 Findings: Injection of Norharmane in low dose (1, 2 mg/kg) after training improve memory retention in Alzheimer's rats while Norharmane in high dose (4 mg/kg) lead to further impairment of memory retention in Alzheimer's rats of streptozotoc model. So that presence time in the light area before entering to dark area in the STZ+norharmane (2 mg/kg) group were significantly higher than STZ group (P<0.05).
 Discussion & Conclusion: According to findings, Norharmane, as inverse agonists of benzodiazepine receptors in low doses may be useful through stimulation GABA receptors for Alzheimer's disease treatment.