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Comparative analysis of expression and secretion of placental leptin in mammals
Department of Biology, Boston University, Boston, Massachusetts 02215 Submitted 23 December 2002 ; accepted in final form 24 March 2003 Increased plasma level of leptin appears to be a ubiquitous feature of pregnant mammals. The mechanisms by which leptin levels are increased may be species specific...
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Published in: | American journal of physiology. Regulatory, integrative and comparative physiology integrative and comparative physiology, 2003-08, Vol.285 (2), p.438-R446 |
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Main Authors: | , , , , , , |
Format: | Article |
Language: | English |
Subjects: | |
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Summary: | Department of Biology, Boston University, Boston, Massachusetts
02215
Submitted 23 December 2002
; accepted in final form 24 March 2003
Increased plasma level of leptin appears to be a ubiquitous feature of
pregnant mammals. The mechanisms by which leptin levels are increased may be
species specific, however, with some species upregulating adipose leptin
production and others expressing leptin in the placenta. Placental leptin
expression was examined in representative species of the two most abundant
mammalian orders, Rodentia and Chiroptera, and in cultured human
choriocarcinoma (BeWo) cells. Leptin mRNA was expressed in BeWo cells and in
placentas of Myotis lucifugus (little brown bat), Eptesicus
fuscus (big brown bat), and Rattus norvegicus (laboratory rat),
but not the common laboratory mouse Mus musculus . cAMP stimulated
secretion of leptin from BeWo cells and also stimulated leptin mRNA expression
in the cells. In addition to adipose and placental tissue, leptin transcript
in M. lucifugus was detectable in heart, spleen, and liver, but not
in lung, brain, and kidney. Hepatic expression was also observed in E.
fuscus , but not in mice or rats, and did not appear to result from
hepatic fat deposition. Leptin cDNA was cloned and sequenced from M.
lucifugus placenta and shared up to 95% homology with other mammalian
leptin cDNAs. It is concluded that 1 ) placental leptin expression and
secretion are species-specific traits, 2 ) placental leptin production
represents one of three major mechanisms for achieving high circulating
maternal leptin levels during pregnancy, the others being upregulation of
adipose leptin production and production of circulating leptin-binding
proteins, and 3 ) hepatic leptin expression in pregnant insectivorous
bats may be an adaptation resulting from the presence of extremely low amounts
of subcutaneous fat during pregnancy and lactation in these species.
bats; adipose tissue; energy homeostasis; reproduction; placenta
Address for reprint requests and other correspondence: E. P. Widmaier, Dept.
of Biology, Boston University, Boston, MA 02215 (E-mail:
widmaier{at}bu.edu ). |
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ISSN: | 0363-6119 1522-1490 |
DOI: | 10.1152/ajpregu.00776.2002 |