Call it a spice route to tackle depression. A cocktail of two molecules from kitchen spices widely used in Indian curries may help in treating depressive disorders, a new study on laboratory rats by researchers in Chandigarh has suggested.

Shrinivas Kulkarni and his colleagues at Panjab University, Chandigarh, have shown that a combination of curcumin from turmeric and piperine from the pepper plant can reverse behavioural problems in rats induced by chronic stress.

Life hasn’t been always fun for the rats in the Kulkarni’s laboratory at the University Institute of Pharmacological Sciences. Over a 21-day period of studies, each day, some rats had to swim in near ice cold water for five minutes, some found their tails being pinched for five minutes, and some had to swim 20 minutes. Such tasks induced chronic stress and tended to make the animals immobile for relatively long periods of time.

The researchers have found that treatment with curcumin significantly reversed the chronic unpredictable stress-induced immobility in the rats. The treatment also appeared to reverse some biochemical changes and depletion of brain chemicals that appear associated with chronic stress. The findings have just been published in the journal Pharmacology, Biochemistry and Behaviour.

The study corroborates curcumin’s potential role in treating depression, first signalled by a study conducted three years ago by researchers at Peking University, Beijing.

But its real significance lies in demonstrating how curcumin could be made effective by adding a bit of piperine. While curcumin is known to have potential medical applications in treating inflammation, infections and even some cancers, a key problem is that it is not easily bioavailable. Curcumin is quickly excreted from the body by its natural clean-up mechanisms.

Kulkarni and his team has shown that piperine can make more curcumin available to the body. They found that while curcumin by itself reversed immobility in the stressed rats — the higher the dose, the greater the effect. But adding just 2.5 milligram per kilogram (mg per kg) weight of the rats significantly increased the effect of curcumin on the anti-immobility effect on the rats.

Their studies have shown that a combination of 20 mg per kg dose of curcumin and 2.5 mg of piperine was more effective than a dose of 40 mg per kg curcumin given all by itself. Although the study was exclusively based on rats, the Panjab University team wrote in their research report that the findings provide “a scientific rationale” for combining piperine and curcumin to treat depressive disorders.