Nicotine's Brain Actions Linked to Reward Pathways

Nicotine's action in the brain explains why smokers report the first cigarette of the day is the most pleasurable.

Neuroscientists at Baylor College of Medicine studied how the brain reacts to nicotine and reported results in the November 27 issue of the journal Nature.

Dopamine release is related to aspects of reward, Dr. Dani says, so it shapes behaviors by giving a reward or feeling of pleasure in response to external stimuli. Receptors in the midbrain neurons, called nicotinic acetylcholine receptors, respond to nicotine as it enters the body after smoking a cigarette.

"We found that as the nicotine first arrives, the neurons burst with activity," Dr. Dani says. "That burst of activity in the neurons causes dopamine release that contributes to the sensation of pleasure."

The first cigarette of the day gives smokers their first exposure to nicotine in eight to 10 hours, so the neurons experience an extreme burst of activity.

Dr. Dani's group also found that over time some nicotinic receptors stop responding and turn off, or desensitize, even though nicotine is still present. These receptors will not respond again until nicotine is removed and the receptors have time to recover.
- From Baylor College of Medicine

Lasers Used to Treat Birthmarks

Treatment for unsightly port-wine stains and strawberry marks has been greatly improved with the use of lasers.

"Most patients get a 50 to 75 percent lightening of the birthmark," says Dr. Moise Levy, a dermatologist at Baylor College of Medicine and co-director of the Texas Children's Hospital Birthmark Center.

Port-wine stains, most often found on the head and neck, are flat purple-red birthmarks that do not disappear with age. Strawberry marks, or hemangiomas, are bright red, protrude from the skin and often go away without treatment.

Both types are formed by masses of small blood vessels in abnormal locations.

"Although strawberry marks often disappear as an infant grows, many leave loose skin, mild scarring or fine blood vessels in their place," Dr. Levy says.

Port-wine stains require five to seven laser treatments at two- to three- month intervals. Strawberry marks can be treated more frequently, and fine broken vessels on the face as often as once a month.

The laser, which uses a yellow light absorbed only by red, reacts with a blood cell protein in the birthmark's vessel mass. The blood vessels absorb the laser's energy and convert it into heat that damages the vessels.

"The body's defense system removes the damaged cells, and when the area heals, the treated vessels are gone," Dr. Levy says. "Treatment is repeated until all visible vessels are gone or lightened."
- From Baylor College of Medicine

Inflammatory Bowel Disease may be Disguised as Other Problems

Inflammatory bowel disease, a chronic illness of the gastrointestinal tract, may be disguised as many other problems in children.

"Growth failure is the most common problem associated with inflammatory bowel disease in children," says Dr. Kathleen Motil of the USDA/ARS Children's Nutrition Research Center at Baylor College of Medicine. "Malnutrition is a major factor that contributes to growth retardation in children."

Victims of inflammatory bowel disease suffer from frequent bouts with diarrhea, abdominal pain, and rectal bleeding. The disease may also disguise itself as rheumatoid arthritis, liver disease, gall bladder disease or eye disease.

Many sufferers may refuse to eat because of a loss of appetite, nausea, or diarrhea associated with food ingestion. Others may lose nutrients because of chronic diarrhea; still others may have intestinal malabsorption.

"Nutritional therapy is a good way to improve growth in children with inflammatory bowel disease," says Dr. Motil, a Baylor assistant professor of pediatrics. "Our studies have shown feeding children a formula high in energy, protein, vitamins, and minerals through a button gastrostomy, a device placed directly into the stomach, reduced the inflammatory process and made them feel better."

Steroids also can promote growth in children with inflammatory bowel disease, but may cause a child to gain a disproportionate amount of fat. - From the USDA/ARS Children's Nutrition Research Center
at Baylor College of Medicine

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©2006 Texas Medical Center

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