Background:Alzheimer's disease (AD) is a prevalent disorder with severe learning and memory defects. Because it has been demonstrated that erythropoietin (EPO) has positive effects on the central nervous system, the aim of this study was to evaluate the effect of EPO on neuronal proliferation in dentate gyrus of hippocampal formation in a well-defined model for AD.Materials and Methods:A rat model of sporadic dementia of Alzheimer's type was established by a bilateral intracerebroventricular injection of streptozotocin (ICV-STZ). Impairment of learning and memory was confirmed 2 weeks after ICV-STZ injection by passive avoidance learning test and then rats were divided into fourgroups:Control, control-EPO, Alzheimer and Alzheimer-EPO. EPO was injected intraperitoneally every other day with a dose of 5000 IU/kg and, finally, the rats were anesthetized and decapitated for immunohistochemical study and neurogenesis investigation (by Ki67 method) in dentate gyrus of hippocampal formation.Results:The results driven from the histological study showed that EPO significantly increases neuronal proliferation in dentate gyrus of hippocampus in the Alzheimer-EPO group compared with the control, control-EPO and Alzheimer groups; however, there were no differences between the other groups.Conclusion:Our results show that even though EPO in intact animals doesnot change neurogenesis in dentate gyrus, it can nonetheless significantly increase neurogenesis if there is an underlying disorder like neurodegenerative diseases.

Background:Studies have shown that Doxepin has anti-inflammatory effects and reduces oxidative stress. Due to the fact that other tricyclic antidepressants have been shown to have neuroprotective effects, this study aimed to investigate the effects of different doses of doxepin on passive avoidance learning in rats.Materials and Methods:Old male Wistar rats were used in this study. Doxepin was administered intraperitoneally (1, 5 and 10 mg/kg) for 21 days. Passive avoidance learning test was used for evaluation of learning and memory. Rats received foot electrical shock on fifteen day, and step through latencies were evaluated one week after the electrical shock in retention phase.Results:Administration of Doxepin considerably increased the step through latencies in the rats that received the doses of 1 and 5 mg/kg (P < 0.05). However, in the dose of 10 mg/kg, there wasn’t any significant change comparing to control group.Conclusion:These results indicate that Doxepin has desirable effects on cognitive functions in low doses. Therefore, Doxepin can be considered as memory enhancers that understanding the underling mechanisms need further investigation.

Background:Studies have shown that pentoxifylline (PTX) in addition to protective effects on blood vessels probably has positive influence against the brain inflammation. Therefore, the aim of this study was to evaluate the effects of PTX on serum levels of interleukin 10 (IL-10) and interferon gamma (IFN-γ) and passive avoidance learning in lipopolysaccharide (LPS)-induced inflammation in rats.Materials and Methods:Inflammation was induced by intraperitoneal (i.p.) injection of LPS (0.5 and 5 mg/kg) in male Wistar rats. After a week, PTX (25 mg/kg; i.p.) was injected for 14 days. Passive avoidance learning test was used for evaluation of learning and memory. Serum levels of cytokines were measured by enzyme-linked immunosorbent assay.Results:The behavioral results did not show any significant effect of LPS and PTX on learning and memory. Both doses of LPS (0.5 and 5 mg/kg) decreased IL-10 significantly (P < 0.05). PTX prevented this reduction just in the LPS 0.5 mg/kg + PTX 25 mg/kg group. Serum level of IFN-γ was increased only in the LPS 0.5 mg/kg + PTX 25 mg/kg group comparing to the LPS 0.5 mg/kg group (P < 0.05).Conclusions:The results showed that LPS-induced inflammation decreased the serum levels of IL-10. PTX could prevent these decreases only in mild inflammation. Both PTX and LPS-induced inflammation had no significant effects on learning and memory; therefore, their effects on CNS require further study.