Chronic treatment with the nitric oxide synthase inhibitor, L-NAME, attenuates estradiol-mediated improvement of learning and memory in ovariectomized rats
نویسندگان
چکیده
INTRODUCTION The role of ovarian hormones and nitric oxide in learning and memory has been widely investigated. OBJECTIVE The present study was carried out to evaluate the effect of the nitric oxide synthase (NOS) inhibitor, N (G)-nitro-L-arginine methyl ester (L-NAME), on the ability of estradiol to improve learning in OVX rats using the Morris water maze. METHODS Forty rats were divided into five groups: (1) ovariectomized (OVX), (2) ovariectomized-estradiol (OVX-Est), (3) ovariectomized-L-NAME 10 (OVX-LN 10), (4) ovariectomized-L-NAME 50 (OVX-LN 50) and (5) ovariectomized-estradiol-L-NAME 50 (OVX-Est-LN 50). The animals in the OVX-Est group were treated with a weekly injection of estradiol valerate (2 mg/kg; i.m.). The OVX-LN 10 and OVX-LN 50 groups were treated with daily injections of 10 and 50 mg/kg L-NAME (i.p.), respectively. The animals in the OVX-Est-LN 50 group received a weekly injection of estradiol valerate and a daily injection of 50 mg/kg L-NAME. After 8 weeks, all animals were tested in the Morris water maze. RESULTS The animals in the OVX-Est group had a significantly lower latency in the maze than the OVX group (p<0.001). There was no significant difference in latency between the OVX-LN 10 and OVX-LN 50 groups in comparison with the OVX group. The latency in the OVX-Est-LN 50 group was significantly higher than that in the OVX-Est group (p<0.001). CONCLUSION These results show that L-NAME treatment attenuated estradiol-mediated enhancement of spatial learning and memory in OVX rats, but it had no significant effect in OVX rats without estrogen, suggesting an interaction of nitric oxide and estradiol in these specific brain functions.
منابع مشابه
Role of L-NAME, a nitric oxide synthase inhibitor, in the improvement of morphine-induced amnesia induced by nicotine
Introduction: Drugs of abuse such as nicotine and morphine used systemically by addicts produce their effects via the mesolimbic dopaminergic pathway. Furthermore, evidence indicates that some behavioral effects of nicotine and morphine are mediated by nitric oxide (NO). Based on these observations, the aim of the present study was to investigate the effects of intra-nucleus accumbens (NAc) ...
متن کاملChronic Treatment by L-NAME differently Affects Morris Water Maze Tasks in Ovariectomized and Naïve Female Rats
Introduction: The role of ovarian hormones and nitric oxide (NO) in learning and memory and their interaction has been widely investigated. The present study carried out to evaluate different effect of L-NAME on spatial learning and memory of ovariectomized (OVX) and sham operated rats. Methods: 32 rats were divided into 4 groups: 1) Sham 2) OVX 3) Sham-LN and 4) OVX-LN. The animals of groups 3...
متن کاملاثر تجویز توأم مورفین و ال- آرﮊینین در ناحیه CA3 هیپوکامپ بر یادگیری و حافظه فضایی موشهای صحرایی نر
Background: Learning and memory are the complicated agents of central nervous system that various regions of brain can be involved in these phenomena, especially regions like hippocamp. Various agents like nitric oxide and morphine can influence learning and memory. About the effects of morphine with other components there was not clear reports so in this study the effect of co-administrati...
متن کاملتأثیر مهارکننده نیتریکاکساید سنتاز در هسته آکومبنس بر روی اثر بهبود بخش نیکوتین در فراموشی القاء شده با اتانول
Background and Objective: Nitric oxide mediated some behavioral effects of nicotine and ethanol in the nucleus accumbens. In the present study, the effects of L-NAME (nitric oxide synthase inhibitor) in the nucleus accumbens on nicotine’s effect in ethanol-induced amnesia were investigated. Materials and Methods: In this experimental study 96 adult male wistar rats were used (12 groups)...
متن کاملThe role of hippocampal nitric oxide in passive avoidance learning
Abstract: Introduction: Nitric oxide (NO) is a retrograde messenger in hippocampal synaptic plasticity which involves in learning and memory processes. Previous studies revealed that hippocampal pyramidal cells contain NO synthase (NOS) enzyme which produce NO and could be a promising target to evaluate the role of NO in brain cognitive functions. So in this study, using NOS inhibitor (L-NAME)...
متن کامل