Study raises caution on new painkillers

March 16th, 2008 - 3:22 pm ICT by admin  

New York, March 16 (IANS) A new class of painkillers may interfere with brain functions such as learning and memory, a new study that advices caution suggests. These painkillers block a receptor called TRPV1, which regulates a neural mechanism called long-term depression, which is believed to be central to establishing memory pathways in the brain, Sciencedaily reported.

Brown University researchers said their findings also suggest that the function of TRPV1 in neural tissue may explain reported side effects of the anti-obesity drug Acomplia, widely used outside the US.

While Acomplia has been approved in Europe, the FDA denied US approval because of concerns that the drug increases risk of depression and suicide.

Findings of the study have been published in the latest issue of the journal Neuron.

TRPV1, or “transient receptor potential vanilloid 1″, is a pain receptor whose activation causes the pain in inflammation. Chemicals such as chili pepper compound capsaicin also trigger it.

Drug companies have been testing TRPV1 receptor blockers to treat the pain of inflammation and nerve damage in the peripheral nervous system (PNS).

However, besides being expressed in the PNS, TRPV1 is expressed in areas of the central nervous system (CNS), including the hippocampus, the brain’s learning centre.

In their experiments with rat brain slices, Kauer and colleagues explored whether TRPV1 plays a role in long-term depression (LTD), which is a weakening of the signaling between neurons that takes place at the connections called synapses.

The researchers said their findings suggest that drugs targeting TRPV1 could act not only on pain receptors in the PNS but in the brain as well. They also wrote that their findings and those of other researchers “indicate that drugs that bind to CNS TRPV1 receptors are likely to influence more than just pain-related functions”.

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