"We want to understand how the sense of smell changes and how the nervous system detects sensory stimuli," said Anne Hart from the Massachusetts General Hospital Center for Cancer Research, who co-authored the study.
For the study well-fed nematodes (roundworms) fled from the noxious smell of the irritant octanol faster than their starved counterparts. The loss of serotonin, which is known to be critical in a nematode response to food, had a similar effect.
In a second step for the study the authors selectively removed pairs of neurons thought to be involved in octanol sensing, they found that the presence of food made little difference to the response.
Worms in which the ASH neurons, which express GPA-11, were ablated did not respond to dilute amounts of octanol regardless of the availability of food, write the scientists.
Through their research, the authors demonstrated how food- and serotonin-regulated changes in a neuronal circuit can affect behaviour. In humans, defects in the regulation of the neurotransmitter serotonin have been linked to a number of behavioral problems, including depression and obsessive-compulsive disorder.
Full findings of the study, 'Feeding status and serotonin rapidly and reversibly modulate a Caenorhabditis elegans chemosensory circuit' are published in the 11-15 October 2004 online edition of Proceedings of the National Academy of Sciences.