Immunohistochemical localization of atrial natriuretic factor and autoradiographic distribution of atrial natriuretic factor-binding sites in the brain of the cave salamander Hydromantes genei (Amphibia, Plethodontidae)
M. Mathieu et al., Immunohistochemical localization of atrial natriuretic factor and autoradiographic distribution of atrial natriuretic factor-binding sites in the brain of the cave salamander Hydromantes genei (Amphibia, Plethodontidae), J COMP NEUR, 437(2), 2001, pp. 240-258
The distribution of atrial natriuretic factor (ANF)-like immunoreactivity i
n the central nervous system of the cave salamander Hydromantes genei (Amph
ibia, Plethodontidae) was investigated by using antisera raised against rat
and human ANF(1-28). Concurrently, the location of ANF-binding sites was d
etermined by autoradiography, using radioiodinated human ANF(1-28) as a tra
cer. In several regions of the brain, including the olfactory bulb, the pre
optic area, the ventral thalamus, the tectum of the mesencephalon, and the
choroid plexuses inside the ventricles, a good correlation was observed bet
ween the distribution of ANF-immunoreactive elements and the location of AN
F-binding sites. Mismatching was found in the habenular nucleus, the commis
sura habenularis, the fasciculum retroflexus, and the interpeduncular nucle
us, which contained high levels of binding sites but were devoid of ANF-imm
unoreactive structures. In contrast, a few other regions, such as the pinea
l gland and the subcommissural organ, showed a high concentration of ANF-li
ke immunoreactivity but did not contain ANF-binding sites. This study provi
des the first localization of ANF-like immunoreactivity and ANF-binding sit
es in the brain of an urodele amphibian. The results show that the ANF pept
idergic system in the cave salamander has an organization more simple than
the organizations described for the brain of frog or other vertebrates. Thi
s feature is probably related to the expression of highly pedomorphic chara
cters in plethodontids. The anatomical distribution of ANF-immunoreactive e
lements and ANF-binding sites suggests that ANF-related peptides may act as
hypophysiotropic hormones as well as neurotransmitters and/or neuromodulat
ors in the salamander brain. (C) 2001 Wiley-Liss, Inc.