Effects of intrahippocampal injection of Leptin on seizure-induced cognitive impairment in male rats

Leptin is a peptide hormone secreted by adipose tissue. Leptin also acts on the hippocampus where it facilitates the induction of long-term potentiation. It also enhances NMDA receptor-mediated transmission. Previous studies have shown that Leptin plays a role in learning and memory. There is evidence that Leptin can have antiepileptic effects. This suggests that Leptin in the brain may be involved in cognitive deficits associated with seizure. In the current study, the possible effects of Leptin on cognitive impairment following PTZ-induced seizures were examined in male rats. Male rats were divided into 5 groups including control and pentylenetetrazol (PTZ) plus saline or Leptin (0.25, 1 or 2 μg/kg). After one week of intrahippocampal surgery period, PTZ (50 mg/kg) was injected intraperitoneally and after 30 min, saline or different doses of Leptin were injected into bilateral CA1 region. Behavioral tests (Open field, Morris water maze, Novel object recognition test and shuttle box) were done thirty minutes after the intrahippocampal injection of saline or Leptin. Our results demonstrated the significant impairment of learning and memory in PTZ group (P < 0.01). Intrahippocampal injection of Leptin at the dose of 1 μg/kg significantly improved learning and memory in PTZ + Leptin group compared to PTZ group. Obtained results showed that Leptin in PTZ-treated animals has an improving effect on learning and memory.