Abstract

The present investigation was carried out to find the role of glutamate in development of depression in asthma using mice. Female albino mice were divided into five groups, group I- normal control, group II- depression, group III- asthma, group IV- asthma+depression and group V- memantine-treated asthma+depression. Various respiratory parameters, histopathology of lungs, forced swim test, sucrose preference test and brain neurotransmitter levels were measured. A significant decrease in tidal volume and air flow rate as well as increase in respiratory rate was found in depression asthmatic group as compared to only asthmatic group, only depression group and normal control group. These same animals when subjected to despair swim test and sucrose preference test, the immobility time was significantly increased whereas preference to the sucrose solution was significantly decreased. Glutamate, 5-HT and norepinephrine levels were significantly increased and dopamine level significantly decreased in depression group and depression along with asthma group as compared to normal control group or asthma group. Treatment with memantine showed improvement in the respiratory parameters and depression parameters as compared to untreated asthmatic mice with depression. Moreover, a positive correlation was observed between airflow rate and immobility. Also, a direct correlation was observed between brain glutamate level and airflow rate as well as brain glutamate level and immobility. These results suggested that glutamate might be the key mediator involved in development of depression in asthma.