Angiotensinergic Neurotransmissions in the Medial Amygdala Nucleus Modulate Behavioral Changes in the Forced Swimming Test Evoked by Acute Restraint Stress in Rats

Figures

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  Figure 1. Microinjection sites into the MeA. (Left) Photomicrograph of a coronal brain section illustrating bilateral injection sites in the medial amygdaloid nucleus (MeA) of a representative animal. (Right) Diagrammatic representation based on Paxinos & Watson [40] showing the microinjection sites in the medial amygdaloid nucleus (MeA) of the selective AT1 receptor antagonist losartan (red circles), the selective MAS receptor antagonist A-779 (blue circles), the selective AT2 receptor antagonist PD123319 (green circles) and vehicle (white circles). The number shown in the figure can be smaller than the total number of animals used in this experiment due to the overlap of some injection sites. Opt—optical tract.

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  Figure 2. Immobility time and latency to the first bout of immobility in the forced swimming test (FST) of animals submitted to an acute session of restraint stress and that received bilateral microinjection into the medial amygdaloid nucleus (MeA) of the selective AT1 receptor antagonist losartan (1 nmol/100 nL, n = 9), the selective MAS receptor antagonist A-779 (0.1 nmol/100 nL, n = 10), the selective AT2 receptor antagonist PD123319 (5 nmol/100 nL, n = 8) or the vehicle (saline, 100 nL, n = 21); as well as animals who were not submitted to restraint stress (non-stressed, n = 15). (Top) Immobility time each 5 min during the pre-test session (first session, left), which was performed immediately after the end of the acute restraint session, and during the entire test session (second session, right) that occurred 24 h after the pre-test session of the FST. The bars and circles represent the mean ± SEM. Results of the first session were analyzed using two-way ANOVA followed by Bonferroni post-hoc test, whereas one-way ANOVA was used in the results of the second session. * p < 0.05 vs. non-stressed group (during the entire period for the results of the first session); # p < 0.05 vs. vehicle…

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  Figure 3. Swimming and climbing time in the forced swimming test (FST) of animals submitted to an acute session of restraint stress and that received bilateral microinjection in the medial amygdaloid nucleus (MeA) of the selective AT1 receptor antagonist losartan (1 nmol/100 nL, n = 9), the selective MAS receptor antagonist A-779 (0.1 nmol/100 nL, n = 10), the selective AT2 receptor antagonist PD123319 (5 nmol/100 nL, n = 8) or the vehicle (saline, 100 nL, n = 21); as well as animals who were not submitted to restraint stress (non-stressed, n = 15). (Top) Swimming time each 5 min during the pre-test session (first session, left), which was performed immediately after the end of the acute restraint session, and during the entire test session (second session, right) that occurred 24 h after the pre-test session of the FST. (Bottom) Climbing time each 5 min during the pre-test session (first session, left), and during the entire test session (second session, right). The bars represent the mean ± SEM. Results of the first session were analyzed using two-way ANOVA, whereas one-way ANOVA followed by Bonferroni post-hoc test was used in the results of the second session. # p < 0.05 vs. vehicle…