A Belgian-British team of researchers has found a way to design drugs able to target specific areas of the brain. Presented in the journal Proceedings of National Academy of Sciences (PNAS), the findings could help researchers develop treatments to fight diseases without triggering adverse events in other parts of the nervous system.
Researchers led by Professor Neil Marrion at the University of Bristol’s School of Physiology and Pharmacology in the United Kingdom worked on a subtype of ion channel called SK (Small conductance calcium-activated potassium) channels. Ion channels are proteins able to control the excitability of nerves. Ion channels, which are constructed like an electrical circuit, enable the flow of 'charged' potassium, sodium and calcium ions to enter or exit cell membranes through a network of pores formed by the channels, a subtype of which is the SK channel family.
Apamin, a natural toxin found in bee venom, was used by the team. This toxin can block various SK channel types. These channels allow potassium ions to flow in and out of nerve cells that control activity. Benefitting from apamin's ability to block a subtype of SK channel better than the others, the researchers successfully identified how three subtype SK channels (SK1 through SK3) can be selectively blocked.
The ability of apamin and other ligands to block SK channels reveals how the channels are folded to enable the binding of a drug. So drugs can be created to block those SK channels that are composed of at least two SK channel subunits to ensure a more effective fight against dementia and depression.
'The problem with developing drugs to target cellular processes has been that many cell types distributed throughout the body might all have the same ion channels,' explains Professor Neil Marrion of the University of Bristol, one of the authors of the study. 'SK channels are also distributed throughout the brain, but it is becoming obvious that these channels might be made of more than one type of SK channel subunit. It is likely that different nerves have SK channels made from different subunits. This would mean that developing a drug to block a channel made of only one SK channel protein will not be therapeutically useful, but knowing that the channels are composed of multiple SK subunits will be the key.'
Commenting on the results of the study, co-author Vincent Seutin from the Centre Interfacultaire de Recherche du Médicament at the Université de Liège in Belgium says: 'Our study also shows a difference in the way apamin and non-peptidic (potentially a useful drug) ligands interact with the channel. This may have important implications in terms of drug design.'