The scientists determined the improper signaling can be caused by a genetic mutation or exposure to toxins such as nicotine and lindane, a pesticide. They also found that when nerve cells become overexcited and fire incorrect signals too rapidly, proteins in target muscle cells fold incorrectly and become non-functional.

Researchers from Northwestern University, Harvard University and Portugal's University of Lisbon said their study provides strong evidence that nerve cell activity can directly affect the protein folding process in muscle cells. The note that neurodegenerative diseases, certain cancers, muscular dystrophy and aging cause loss of muscle cell function and their findings might illuminate how that occurs.

"We may have discovered an unexpected basis for a number of human diseases," said Professor Richard Morimoto of Northwestern University, one the study's lead authors. "We've shown that pesticides … have profound effects on nerve communication -- even more than we expected," he added.

The study appears in the journal Genes & Development.