Washington, October 23 : Johns Hopkins researchers have found that tiny hair-like cell structures known as cilia play a significant role in humans’ ability to sense touch and heat.

The researchers say that humans and genetically engineered mice lacking functional cilia respond more slowly to physical sensations like exposure to hot water or a sharp poke with a stick.

Published in the Proceedings of the National Academy of Sciences, the new findings may pave the way for doctors to better understand diseases already linked to defective cilia like Bardet-Biedl syndrome (BBS) and polycystic kidney disease (PKD)

Dr. Nico Katsanis, associate professor at Johns Hopkins’ McKusick-Nathans Institute of Genetic Medicine, recently showed that cilia play an important role three of the five senses, namely, vision, hearing and smell.

“That leaves two unexplored possibilities. Taste and touch; we tried touch,” says Katsanis.

During the course of study, the researchers performed a pair of tests on both normal mice and engineered mice with defective cilia (BBS). They immersed the tails of the mice in warm water and measured how long before the mice flicked their tails.

For testing mechanical force, the researchers applied increasing, but not painful, pressure to the hind feet of mice until they withdrew their paws.

In both tests, mice with defective cilia responded later than normal rodents.

“These mutant mice can still feel the heat and pressure. They just have a higher threshold for registering the sensation,” says Katsanis.

Dr. Norimasa Mitsuma, a postdoctoral student in Katsanis’s lab, also showed that that the defective cilia were not hindering brain function.

The researchers also recruited nine patients with Bardet-Biedl syndrome (BBS)—an inherited disorder characterized by obesity, polydactyly and vision loss—in order to find out whether people with inherited conditions that affect cilia also had different sensation thresholds.

The subjects were assigned to seven simple perception tests, such as detecting the vibration of a tuning fork on their wrist or guessing the weight and shape of an object just by feeling it.

All nine patients were less able than non-BBS patients to form the right response in at least some of the tests.

“This will certainly aid our efforts to both diagnose ciliopathies and relate to the patients. People with ciliopathies are often thought to have mental retardation or autism because they appear ‘slow’. Now it appears that many aspects of their mental capacity may be just fine, they are just slow because they can’t sense things as well as other individuals,” says Katsanis. (ANI)