Chronic overeating and stress are tied to an increased risk of depression and anxiety, researchers said.
Researchers found that the anaesthetic ketamine reverses depression-like symptoms in rats fed a high-fat diet in a similar way it combats depression and synaptic damage of chronic stress in people.
"The effects of a high-fat diet overlap with those of chronic stress and could also be a contributing factor in depression as well as metabolic disorders such as Type 2 diabetes," said study senior author Mr. Ronald Duman, professor at the Yale University in US.
Scientists showed that ketamine, also known as "Special K" and abused as a recreational drug, can quickly and dramatically reduce symptoms of chronic depression in patients who are resistant to typical antidepressant agents.
Subsequent research showed that ketamine activates the mTORC pathway, which regulates the synthesis of proteins involved in creation of synaptic connections in the brain that are damaged by stress and depression.
The pathway is also involved in cellular responses to energy and metabolism, and people with metabolic disorders like Type 2 diabetes are also at higher risk of depression.
Researchers wanted to explore whether diet might influence behaviour of rats fed six times the normal amount of fat.
They found that after four months of the diet, pathways involved with both synaptic plasticity and metabolism were disrupted, and the rats exhibited signs of depression and anxiety.
They also found that a single low dose of ketamine reversed those symptoms quickly, and reversed the disruption of mTORC signalling pathways.
Duman cautioned that the effects of ketamine on metabolism need more research and its proper dosage and use for depression are still a subject of clinical trials.
The study was published in the journal Neuropharmacology.
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