Copyright 1999 American Medical Association. All Rights Reserved.
Applicable FARS/DFARS Restrictions Apply to Government Use.1999
To the Editor: The protein hormone leptin appears
to act as an afferent signal from adipose tissue to the brain indicating the
state of energy reserves.1 Both serum and
cerebrospinal fluid (CSF) leptin concentrations increase with body fat2; however, CSF concentrations are generally 2 orders
of magnitude lower than serum concentrations. The transport of leptin across
the blood-brain barrier appears to occur via a saturable system, as has been
demonstrated in mice.3 This suggests a mechanism
by which obese people can be "resistant" to their higher circulating levels
of leptin2 and suggests that exogenous administration
of leptin to treat obesity might be ineffective.2
Results of a double-blind clinical trial demonstrated that exogenous leptin
(daily bolus subcutaneous injections of up to 0.3 mg/kg) has a biologic effect.4 We report here data from a separate cohort of this
clinical trial indicating that recombinant leptin enters the CSF.
Fujioka K, Patane J, Lubina J, Lau D. Public Health History. JAMA. 1999;282(16):1517–1518. doi:10-1001/pubs.JAMA-ISSN-0098-7484-282-16-jbk1027
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