BDNF has been shown to play a key role in the kind of neural and behavioral plasticity that is induced by the use of cocaine and other stimulants. Furthermore, it has been demonstrated that the mode of action of BDNF in this regard is intimately connected with the mesolimbic dopamine (DA) system that represents a key reward circuit in the brain. Dopamine is one of major neurotransmitters in the brain that is involved in many diverse brain functions. It is the irreversible loss of dopamine-producing cells that results in the symptoms associated with Parkinson’s disease. The net result of the interaction of BDNF with DA system is the promotion of further actions of stimulant drugs.
Dr. Ja Wook Koo and his colleagues at the Fishberg Department of Neuroscience and Friedman Brain Institute at the Mount Sinai School of Medicine in New York have implicated BDNF in the mode of action of the opiate drug, morphine and have helped elucidate the mechanism through which it works. In contrast to stimulants, opiates exert their effect on the brain through the promotion of DA signaling by the inhibition of ϒ-aminobutyric acid (GABA) – an important neurotransmitter in the brain that plays a role in regulating neuronal excitability through an inhibitory pathway. The investigators have clearly shown that BDNF is, in fact, a negative modulator of morphine action.
This is an important finding in that is helps elucidate the mechanisms involved with brain-associated adaptations within the reward circuitry that occur with the use of morphine – a drug that is widely used to treat severe chronic pain especially at the end of life.