A Hormone Ensures its Future

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http://wis-wander.weizmann.ac.il news@weizmann.ac.il November 2011

Much of the body’s chemistry is

controlled by the brain – from

blood pressure to appetite to food

metabolism. In a study published

recently in Developmental Cell, a team

of scientists led by Dr. Gil Levkowitz

of the Weizmann Institute has revealed

the exact structure of one crucial brain

area in which biochemical commands

are passed from the brain cells to the

bloodstream and from there to the

body. In the process, they discovered a

surprising new role for the “hormone

of love,” showing that it helps to direct

the development of this brain structure.

The area in question, the neurohypophysis,

is an interface between

nerve fibers and blood vessels located

at the base of the brain. Here, some

of the major brain-body interactions

take place: Hormones released from

nerves into the blood vessels regulate

a series of vital body processes,

including the balance of fluids and

uterine contractions in childbirth.

Although the neurohypophysis

has been studied for more than a

century, the scientists in the Weizmann

Institute-led study developed new

genetic tools that enabled them to

examine the exact three-dimensional

arrangement of this brain structure

and clarify the cellular and molecular

processes leading to its formation.

Since the human neurohypophysis is

exceedingly complex, the scientists

performed the research on live

embryos of zebrafish. These fully

transparent embryos offer a unique

model for studying the vertebrate

brain, lending themselves to genetic

manipulation with relative ease and

enabling researchers to observe the

actual formation of a neurohypophysis

under a microscope.

The study revealed a surprising

new function for the hormonal

messenger oxytocin, dubbed the

“hormone of love” because, in addition

to controlling appetite and such female

reproductive behaviors as breastfeeding,

it is also involved in mother-child

and mate bonding. The scientists

showed that oxytocin, one of the two

major hormones secreted in the adult

neurohypophysis, is involved in the

development of this brain area already

in the embryo. At this stage, the

oxytocin governs the formation of new

blood vessels. “The messenger helps

to build the road for transmitting its

own future messages,” says Levkowitz.

Developmental Cell highlighted the

study’s findings in a preview headlined,

“The Hormone of Love Attracts

a Partner for Life.”

These findings provide an

important advance in basic research

because they shed light on fundamental

brain processes, but in the future they

might also be relevant to the treatment

of disease. Since the neurohypophysis

is one of only a few portions of the

brain able to regenerate after injury, an

understanding of how it is formed may

one day help achieve such regeneration

in other parts of the central nervous

system.

The research was conducted in

Levkowitz’s lab in the Molecular Cell

Biology Department by Ph.D. student

Amos Gutnick together with Dr. Janna

Blechman. The Weizmann scientists

worked in collaboration with Dr. Jan

Kaslin of Monash University, Australia;

Drs. Lukas Herwig, Heinz-Georg

Belting and Markus Affolter of the

University of Basel, Switzerland; and

Dr. Joshua L. Bonkowsky of the

University of Utah, United States. ❙

Dr. Gil Levkowitz’s research is

supported by the Dekker Foundation;

the Kirk Center for Childhood Cancer

and Immunological Disorders; and

the Irwin Green Alzheimer’s Research

Fund. Dr. Levkowitz is the incumbent

of the Tauro Career Development

Chair in Biomedic