, Farhad Valizadegan, Mohammadreza Zarrindast,
Volume 4, Issue 2 (9-2017)
Abstract
Septohippocampal system plays an important role in regulating fear and anxiety behaviors. In this study, the effects of histamine injected into the dorsal hippocampus and opioidergic agents into medial septum on the anxiety-like behaviors in rats were analyzed, using the Elevated Plus-Maze (EPM) test. Injection of 1 and 5 μg/rat histamine into dorsal hippocampus had no effect on anxiety-like behavior, while injection of 10 μg/rat histamine increased the percentage of open arm time (%OAT) and open arm entry (%OAE), which indicated the anxiolytic effects of histamine. Microinjection of morphine, μ-opioid receptor agonist, into the medial septum (1μg/rat) increased the (%OAT) and (%OAE). Doses of 0.25, 0.5 μg/rat morphine had no effect on anxiety. Co-administration of histamine ineffective dose (1μg/rat) to the dorsal hippocampus and ineffective dose of morphine (0.25µg/rat) to the medial septum increased the (%OAT) and (%OAE). Subsequently, injection of different doses of naloxone (1, 2, 4 µg/rat), as an opioid receptor antagonist, into the medial septum in the presence and absence of an effective dose of histamine (10 µg/rat) in the dorsal hippocampus, was studied. Injection of naloxone (4 µg/rat) into medial septum decreased the (%OAT) and (%OAE), but did not alter the locomotor activity, which indicated the anxiogenic effects of naloxone. Simultaneous injection of histamine (10 µg/rat) into dorsal hippocampus with doses of naloxone (1, 2, 4 µg/rat) into the medial septum, indicate anxiolytic effects and increased %OAT and %OAE in Elevated Plus Maze, although when the dose of naloxone was 4μg/rat, this effect was less observed. The results indicate that hippocampus histaminergic system interact with medial septum opioidergic system and the interaction of these systems modulates anxiety behavior.
Farhad Valizadegan, Maryam Rahimi Tesyie,
Volume 5, Issue 1 (6-2018)
Abstract
The Basolateral Amygdala (BLA) has modulatory effects on working and reference memory. The aim of this study was the evaluation of effects of dopaminergic system in the BLA of rats on working and reference memory behaviors. The number of working and reference errors and time spent in the arms by rats were measured in the radial arm maze according to DSWS protocol. The animals were cannulated in the BLA bilaterally. The microinjection of low dose (0.005µg/rat) and high dose (0.5 µg/rat) of apomorphine have indicated a significant decrease in number of working memory error. But, there was not any change in the numberof reference memory error that showing the improvement of working memory. While the injection of moderate dose apomorphine (0.05 µg/rat) increased these parameters and also enhanced the spent time in working arm that presenting both memories damage. The chlorpromazine injection (2 µg/rat) decreased the number of working and reference memory errors representing the improvement of these memories. Microinjection of chlorpromazine (2 µg/rat) with different doses of apomorphine had no significant change on the both number of errors and the time spent in comparison with control groups. These findings show that BLA dopaminergic system modulates the working and reference memory through that both of (D1/D2) receptors. Also, the effect of this system in BLA is the resultant function of the both receptor families.
