The tiny spheres inside brain cells that ferry chemical messengers into the synapse make their rounds much more expeditiously than once assumed, National Institute of Mental Health (NIMH) - funded researchers have discovered. They used a dye to track the behavior of such synaptic vesicles in real time, in rat brain cells. Rather than fusing completely with the cell membrane and disgorging their dye contents all at once, brain vesicles more often remained intact, secreting only part of the tracer cargo in each of several repeated, fleeting contacts with the membrane, report Richard Tsien, D.Phil., Stanford University, and colleagues Alex Aravanis and Jason Pyle, in the June 5, 2003 Nature.
Dubbed "kiss-and-run" recycling, this allows for more efficient communication between brain cells, suggest the researchers.
Brain cells communicate in a process that begins with an electrical signal and ends with a neurotransmitter binding to a receptor on the receiving neuron. It lasts less than a thousandth of a second, and is repeated billions of times daily in each of the human brain's 100 billion neurons. Much of the action is happening inside the secreting cell. There, electrical impulses propel vesicles into the cell wall to spray the neurotransmitter into the synapse. Likened to soap bubbles merging, or bubbles bursting at the surface of boiling water, this process of membrane fusion (*RealPlayer format) may hold clues about what goes wrong in disorders of thinking, learning and memory, including schizophrenia and other mental illnesses thought to involve disturbances in neuronal communication.
Neurons must recycle a finite number of vesicles.
In "classical" membrane fusion, the vesicle totally collapses and mixes with the cell membrane, requiring a complex and time-consuming retrieval and recycling process. Yet, Tsien and colleagues point out that this process was discovered in huge neurons, such as those in squid giant synapses, with tens oPage: 1 2 3 Related biology news :1
Contact: Jules Asher
NIH/National Institute of Mental Health
. Brain has center for detecting sound motion2
. Brains reward circuitry revealed in procrastinating primates3
. Brain serotonin enzyme finding might explain psychiatric disorders4
. Brain development and puberty may be key factors in learning disorders5
. Organization for Human Brain Mapping 2004 Annual Meeting6
. Brain disease research, particle physics meet in the middle (ware)7
. Brain control8
. Brain cells become more discriminating when they work together9
. Brain signal predicts working memory prowess10
. Brain areas identified that decode emotions of others11
. Brain Centre gives Wales a world lead