Neuroprotective Agents for the Treatment of An Ischemic Stroke

Michael Young

An ischemic stroke is a widely spread disease nowadays. It is faced by millions of older people all over the world. However, it has become a widely spread phenomenon among younger patients as well. An ischemic stroke occurs when a cerebral vessel is shut by a thrombus. As a result, the obstruction of the blood flow occurs to a part of the human brain. Currently, the only effective and proven medical treatment for acute ischemic stroke presupposes the usage of tissue plasminogen activator (tPA). It is a thrombolytic agent which is specially made to remove the thrombus from the blood vessel. After its usage the blood flow is normalized.

When an ischemic stroke occurs a filling defect appears inside the vessel. It may be a high-grade stenosis at the branching point. Large vessel stenosis and occlusions account for about one-third of ischemic strokes. Even though the thrombolytic therapy is quite available today, stroke remains the fifth main cause of death in America and a main cause of adult disability. There is an urgent need in the methods of achieving better results in functional recovery of patients who have survived the stroke. Physicians all over the world continue looking for the ways to reduce such a terrible impact of stroke on society.

Neuroprotective agents have recently become another approach to the treatment of strokes. These substances have generated long-term interest among the scientists in different countries. Nowadays, neuroprotective agents are used in order to save ischemic neurons in the human brain from undoubtful injury after a stroke. A number of studies in animals showed that the onset of complete ischemia occurs after at least four hours. In this period many potentially viable neurons "live" in the ischemic penumbra. The ischemia may be less complete in people, and this period of time may be longer. The only disadvantage is that human patients who face an ischemic stroke are usually older.

Due to the fact that some neuroprotective drugs are able to reduce ischemic damage in animals suffering from a stroke, there is hope that these substances may be efficient for people as well. Unfortunately, there is lack of pharmaceutical research. Many scientists and investigators are looking for a safe agent that would be able to limit ischemic damage in people facing the stroke.

The main action of neuroprotective agents consists in the decrease of the injury of neurons in the ischemic penumbra. It means that the neurons in the penumbra will suffer from the possible injury at early time points less than the neurons in the infarct core. Some of these agents can assists neuronal receptors to decrease the release of excitatory neurotransmitters. The latter can be the cause of the early neuronal injury.

A number of neuroprotective agents prevent potentially harmful events which may occur in association with the renewal of blood circulation. It is clear that the return of blood circulation in the human brain is usually highly beneficial, however, reperfusion may lead to brain injury as well. The blood may contain leukocytes that may block small vessels and be toxic for the human brain.