HEALTH NEWS  
 BRAIN
 Gland tied to use of body clock
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 WASHINGTON (AP) -- A tiny gland
 lodged deep in the brain has been
 found to have nerve-like circuits to
 other parts of the organ, and
 scientists say these connections may
 help explain the gland's role in
 setting the body's biological clock.

 Researchers at the National
 Institutes of Health, working with
 West German scientists, said their
 discovery using hamster brains also
 may help show how the pineal gland
 influences mood and behavior,
 including a form of depression that
 changes with seasonal exposure to
 light.

 The discovery shows that the pineal
 gland is not just a free-floating,
 hormone-releasing structure that
 influences the rest of the brain in a
 general way, as has long been
 believed, said a report published
 Friday in the journal Science.

 Rather, because the gland is
 "hardwired" into the brain with
 nerve-like connectors, it also may
 specifically act upon certain areas
 to affect behavior, mood and day-
 night cycles of the body, it said.

 The finding "dramatically changes
 our concept of the mammalian pineal
 gland," said Dr. David Klein, a
 neuroscientist at the NIH's National
 Institute of Child Health and Human
 Development.

 "Everyone thought the pineal gland
 only worked like a radio, sending
 hormonal messages diffusely through
 the blood like a radio sends its
 signals through the air," he said.
 "But it may also work like a
 telephone, sending messages directly
 to specific targets through nerves
 that act like phone wires," Klein
 added.

 Despite the general similarities among
 mammal brains, the researchers said
 further research is needed to tell if
 the connections seen in hamsters also
 exist in humans. They have begun
 studies of monkey brains as the next
 step.

 The pineal gland is a light-sensitive
 organ closely related to retina cells
 in the eye, Klein said in an
 interview. Both types of tissue are
 believed to have evolved from a
 primitive light-receptive organ found
 in early animals, and they share
 certain proteins and chemicals found
 nowhere else in the body, he said.

 Because the pineal is in the center
 of the brain, it gets its light cues
 from a neural pathway which connects
 it with the retinas of the eyes. The
 gland secretes varying levels of
 hormones depending upon lighting
 conditions.
 Klein collaborated with German
 scientists at Justus-Liebig University
 of Giessen to study pineal gland cells
 in hamster brains. They obtained an
 antibody to a common pineal-retina
 protein from researchers who
 developed it at the National Eye
 Institute.

 Using a special microscope and light
 that makes the antibody glow when it
 attaches to the right tissue, the
 researchers saw brightly colored
 pineal cells in cross-sections of
 hamster brains.

 To their surprise, the scientists said
 they also found colored threads
 running from pineal cells to regions
 of the brain that connect to areas
 that influence mood, sleep and
 behavior.

 Klein said this finding could have
 implications for a number of
 disorders that have baffled
 scientists, including seasonal
 affective disorder, or SAD, a form of
 depression.

 SAD, which occurs as days grow
 shorter in winter and disappears when
 days lengthen in spring, represents
 between 3 percent and 5 percent of
 depression cases, he said.

 Melatonin, a hormone secreted by the
 pineal gland, increases at night in
 the dark and decreases in light. But
 researchers looking into SAD have
 not succeeded in linking the hormone
 to the disease. However, Klein said,
 since SAD patients improve when
 exposed to bright light, the pineal
 still may play a role in the disorder
 through a more direct connection to
 the brain.