Novel neurotransmitter overturns laws of biology, offers potential for stroke...( t Hopkins in the last five years has po...),Health

t Hopkins in the last five years has pointed to D-serine's role, but the new study, in which researchers have isolated and cloned the enzyme that makes D-serine, shores it up. The enzyme, serine racemase, is as unusual as its product in that it forms D-serine from L forms already in cells. "No other mammalian enzyme behaves like it," Snyder says. The oddity of having an enzyme that converts amino acids from a left to a right-handed form makes it an ideal drug target, he adds.

It invites hope that drugs inhibiting serine racemase in a timely way could damp down production of D-serine and thus squelch activity at NMDA receptors. This would be useful, during a stoke, Snyder says, when lack of oxygen in tissues triggers reactions that greatly overstimulate the NMDA receptor. Overstimulation triggers reactions that destroy nerve cells. "Being able to turn off or turn down the receptors might prevent damage," he adds.

In this study, when the scientists added L-serine to cells artificially constructed to contain the racemase enzyme, most of the L-serine was transformed to its D-serine twin. The researchers also found D-serine and serine racemase concentrated in astrocytes adjacent to NMDA receptors, but less common or nonexistent in other neural tissues.

For years, neuroscientists assumed that NMDA receptors could only be stimulated by a single neurotransmitter, an amino acid called glutamate. They now know that two neurotransmitters are needed to stimulate the receptors. D-serine was recently proposed by the Hopkins scientists as the second, largely because microscope images of tagged D-serine show it's physically near NMDA receptors in the synapse. Also, knocking D-serine out with enzymes quickly stops NMDA receptors from being active.

Hopkins researchers aren't clear why nature would have such a bizarre and highly specific neurotransmitter as D-serine, but Snyder suggests it may be because having two neurotransmitters required to trigger th
'"/>

Contact: Marjorie Centofanti
mcentofanti@jhmi.edu
410-955-8725
Johns Hopkins Medical Institutions
8-Nov-1999

Page: 1 2 3
Related medicine news :

1. Novel therapy tested in mice could chase away cat allergies
2. Novel antibiotic shows promise in shortening treatment duration of tuberculosis
3. Novel p53 gene-based therapy boosts immune system and reduces tumor size
4. Novel drugs help solve Gleevec resistance
5. Novel imaging technique shows abnormal brain anatomy in children with ADHD
6. Novel drug-antidote strategy provides greater control of drug action
7. Novel imaging technique shows lymph nodes, metastases in breast cancer without surgery
8. Novel delivery method for nutrients wins Kaye Innovation Award for Hebrew university students
9. Novel vitamin discovery offers clues for cancer chemotherapy and lipid disorders
10. Novel findings about neovessel formation
11. Novel MRI technique provides clear images of blood flow