The new messengers in the brain
Two new peptides, which are only formed in certain regions of the brain, show a number of characteristics that identify them as messenger substances for signal transmission between nerve cells. Some scientists speculate that these substances are involved in body weight control. “The discovery of a new neurotransmitter is always important. But the presence of the neurotransmitters in the brain makes this work particularly exciting,” says Thomas Kilduff of Stanford University Medical Center. Along with colleagues, he describes the results of the experiments in the Proceedings of the National Academy of Sciences, January 6, 1998.
The two neurotransmitters, called hypocretins by the researchers, are synthesized exclusively by a few groups of cells in the hypothalamus. This pea-sized center in the brain controls such basic functions as body temperature, fluid needs, hunger, and eating habits. "If you show any specialist pictures of the places where the hypocretins are found, they'll think about energy balancing and feeding," says Kilduff. Nevertheless, the messenger substances can have other tasks than contributing to weight control. Only further experiments will be able to clarify this question.
The two neurotransmitters are first produced as a single protein and then cut into two shorter peptides by the nerve cell. These two pieces, Hypocretin 1 and Hypocretin 2, are very similar to each other and are somewhat reminiscent of the hormone secretin, which controls the secretion of bile into the stomach.
Kilduff and his colleagues give three reasons why hypocretin 2 should be considered a neurotransmitter:
- It is synthesized in nerve cells,
- it is packed into vesicles in which neurons store their neurotransmitters,
- and it stimulates neurons in cell cultures to send out electrical signals.
Some pharmaceutical companies have already expressed interest in the discovery. At a conference, Kilduff presented a poster that was well received: “I've never seen so many people come to a poster. Someone from a major pharmaceutical company was there for over an hour and memorized everything.”
The Heidelberger Verlag Spektrum der Wissenschaft is the operator of this portal. Its online and print magazines, including "Spektrum der Wissenschaft", "Gehirn&Geist" and "Spektrum – Die Woche", report on current research findings.
