Effects of intra-amygdala memantine infusion on metabolic symptoms induced by chronic stress in male NMRI mice

Pervious studies indicate an important role for amygdala in stress. In addition, glutamate inputs to the amygdala are activated during stress. In the present study, the effects of amygdala NMDA glutamate receptors inhibition on metabolic symptoms induced by chronic stress in male NMRI mice were investigated. Intra-amygdala uni- or bi-lateral cannulations were performed. Seven days after recovery from surgery animals received different doses of memantine (0.1, 0.5 and 1 µg/mouse) five minutes before inducing stress. Stress was applied for seven consecutive days. Changes in the amount of food and water intake and delay in eating and defecation were considered as indicators for stress. Stress reduced food, while increased water intake and delayed the time of eating and defecation. Intra-amygdala memantine injections exacerbated the effects of stress on food intake except with the medium and high doses in the right side of the nucleus. Memantine also inhibited the effects of stress on water intake except with the medium doses in the right side. Also, reduced delay in the time of eating significantly. On the other hand, memantine inhibited or increased effects of stress on defecation, in a dose- and side- dependent manner. Stress activates glutamatergic systems in the amygdala and impacts the metabolic functions. This effect is probably based on the concentration and the side of neurotransmitter action in the nucleus.