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Fig. 3.3 Overall distribution of kisspeptin/Kiss1 cells and kisspeptin fi bers/Kiss1r mRNA, in the
mammalian brain. The locations of kisspeptin/ Kiss1 cells ( left side ) and kisspeptin fi bers/ Kiss1r
mRNA ( right ), based on studies performed to date, are mapped out on a schematic horizontal
drawing of the mammalian forebrain, midbrain, and hindbrain. Background is modifi ed from sche-
matic in Swanson, Brain Maps III, Elsevier ©2004, courtesy of Dr. Larry Swanson with permis-
sion from Elsevier
while a variable percentage of those in the RP3V of rodents contain dopamine (as
indicated by TH) and/or galanin (Tables 3.3 and 3.4 ); whether these neurotransmit-
ters are found in POA kisspeptin neurons in most other species remains to be deter-
mined. Moreover, the POA population is sexually dimorphic in a number of species,
with more kisspeptin neurons in females than in males; a similar sexual dimorphism
for the ARC population has been reported in sheep and human, but data on this in
rodents is confl icting. Additional kisspeptin neurons are found in other hypothalamic
and extra-hypothalamic areas in some species, but it is unclear whether or not this is
a common distribution and the functional role of these neurons is unknown.
Based on the distribution of kisspeptin fi bers, Kiss1r , and studies of afferent
projections, both populations have functional projections to GnRH cell bodies,
which represent an important site at which kisspeptin acts to stimulate GnRH secre-
tion. Kisspeptin-ir fi bers are also found in the external zone of the median eminence
and there are direct membrane contacts between kisspeptin and GnRH axons in this
region. These kisspeptin fi bers appear to arise primarily from ARC KNDy neurons,
although contacts from more rostral kisspeptin cells cannot be ruled out at this time.
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