[Effects of pioglitazone injection into hippocampal CA1 area on spatial learning and memory deficits in rats]

Pioglitazone from thiazolidinediones generation, represent a new antidiabetic drugs that have been introduced in the world recently. Thiazolidinediones can improve insulin resistance by activating the nuclear peroxoxisome proliferator activated receptor-gamma [PPAR-gamma] and increasing insulin sensitivity in their receptors. Insulin and its receptors are found in specific areas of CNS with a variety of region-specific functions. The effects of insulin in CNS are different from its direct glucose regulation in the periphery. Hippocampus and cerebral cortex distributed insulin/insulin receptor have been shown to be involved in brain cognitive functions. In the present study, the effect of pioglitazone microinjection into CA1 region of rat hippocampus using Morris water maze performance has been investigated. In this experimental study, male N-MRI rats were randomly divided into control, DMF [dimethyl formamide] and pioglitazone groups [0.001, 0.01, 0.1, 1, 10 microg/rat]. Drugs were injected [1 microl/rat] into CA1 region bilaterly during 1 min. Thirty minutes after the intrahippocampal injection of drugs, water maze training was started. Pioglitazone had a dose dependent effect. The spatial learning and memory didn't change with lower dose of pioglitazone, but improved with intermediate doses, while they impaired with higher dose. These results suggest that intrahippocampal injection of pioglitazone may have a dose-dependent effect on spatial learning and memory in rats in range of 0.001 to 1 microg/rat

[Effect of daily injection of morphine on leishmaniose infection in mice]

The aim of this study was to evaluate the effect of chronic injection of morphine on infection with Leishmania major [L. major] in sensitive BALB/c and resistant C57BL/6 mice. Morphine injections [2 times /day with 12 hrs intervals, S.c] were begun one week before parasite inoculation. The first group of mice strains was infused with 1.5mg/kg morphine, the second group with 15 mg/kg, and the control received normal saline. After appearance of local reaction on the site of parasite inoculation, the thickness of inoculated paw and countercurrent paw were measured. At the end, all mice were killed and their spleens and popliteal lymph nodes cells were cultured in the presence of Concanavalin-A, and the level of IL-4 was measured. In C57BL/6, mice local reaction size increased until 5th week and then began to decrease to reach a normal situation. In contrast, in BALB/c mice local reaction continued to increase up to the end of the test, and in some cases led to necrosis. There were no significant differences in local reaction size between tests and controls animals in both strains. In addition, there was not a significant difference at the level of IL-4 in the supernatant between tests and control groups in both two strains. Chronic injection of morphine didn't have a significant effect on resistance of C57BL/6 and sensitivity of BALB/c mice to infection with L. major, that may result from immune system tolerance to affect of morphine