Beneficial Effect of Leptin on Spatial Learning and Memory in Streptozotocin-Induced Diabetic Rats

Abstract

Background: Diabetes mellitus is a chronic disease which may be accompanied by cognitive impairments. The expression of the obesity gene (ob) is decreased in insulin-deficient diabetic animals and increased after the administration of insulin or leptin. Plasma leptin levels are reduced in the streptozotocin (STZ)-induced diabetic rats. Therefore, the deleterious effects of diabetes on memory may be due to the reduction of leptin. Aims: Investigate the effect of subcutaneous injection of leptin on spatial learning and memory in STZ-induced diabetic rats. Study Design: Animal experimentation. Methods: The rats were divided into three groups: 1-control, 2-diabetic, and 3-diabetic-leptin. Diabetes was induced in groups 2 and 3 by STZ injection (55 mg/kg) intraperitoneally (i.p). The animals received leptin (0.1 mg/kg) or saline subcutaneously (s.c) for 10 days before behavioral studies. Then, they were examined in the Morris water maze over 3 blocks after 3 days of the last injection of leptin. Results: The travelled path length and time spent to reach the platform significantly increased in the diabetic group (p<0.001) and decreased with leptin treatment (p<0.01 & p<0.001 respectively); also, a significant increase in path length and time was observed between the diabetic-leptin group and the diabetic group (p<0.01, p<0.001, respectively) in the probe test. Conclusion: Leptin can exert positive effects on memory impairments in diabetic rats. Keywords: Leptin, spatial memory, streptozotocin

Effect of leptin on spatial learning, memory and blood glucose level in streptozotocin induced diabetes mellitus in male wistar albino rats

“…These results are in line with the findings of the study conducted by Ghasemi et al 12 Ghasemi and his colleagues in their study showed that leptin administration in the same dose as the one used in our study brought about a decrease in the levels of blood glucose in the rats. This decline in the blood glucose paralleled the improvement in cognition seen in their study.…”

“…Rats after the successful induction of diabetes were subjected to behavioural assessment in the T maze test after completing the required treatment lengths. 12…”

“…It was dissolved in distilled water to get the concentration of 1 mg/ml and was given to the rats in a dose of 0.1 mg/kg of body weight subcutaneously (S.C.). 12…”

Leptin reduces pathology and increases adult neurogenesis in a transgenic mouse model of Alzheimer’s disease

“…Within the past decade, researchers showed a role for leptin in neuroprotection and hippocampal neurogenesis. In animal models, leptin administration facilitates learning and alter synaptic plasticity (Moult et al, 2010;Luo et al, 2015;Ghasemi et al, 2016). Additionally, this adipokine attenuates Tau hyperphosphorylation in neuronal cells and protects against Aβ-induced neurotoxicity in cellular models (Garza et al 2008, Doherty et al, 2013Liu et al, 2015).…”

Adipobiology of the brain: From brain diabetes to adipose Alzheimer‘s disease

“…However, the brain (mostly hypothalamus) is not the only target for leptin and other adipokines, as well as the food intake is not the only biological e ect of these adipokines. Rather, some adipokines support various metabolic and cognitive functions and exert both metabo-and neurotrophic actions (13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24). Current data of adipose-derived neuroendocrine and neurotrophic factors are summarized in Tables 1, 2.…”