Organization of vasoactive intestinal peptide-like immunoreactive system in the brain, olfactory organ and retina of the zebrafish, Danio rerio, during development
M. Mathieu et al., Organization of vasoactive intestinal peptide-like immunoreactive system in the brain, olfactory organ and retina of the zebrafish, Danio rerio, during development, BRAIN RES, 888(2), 2001, pp. 235-247
The localization of vasoactive intestinal peptide (VIP)-like immunoreactivi
ty was investigated in the brain, olfactory system and retina of the zebraf
ish, Danio rerio, during development and in juvenile specimens, by using th
e indirect immunofluorescence and the peroxidase-antiperoxidase methods. In
24 h post fertilization (hpf) embryos,VIP-like immunoreactive cells were p
resent in the olfactory pit, the retina, and several regions of the brain,
including the dorsal telencephalon, the diencephalon, the tegmentum of the
mesencephalon, the caudal rhombencephalon and the anterior pituitary. In 48
hpf embryos, additional VIP-like immunoreactive cell bodies were found in
the ventral telencephalon, whereas in the diencephalon VIP-like immunoposit
ive cells were more concentrated within the ventro-caudal hypothalamus. Dur
ing the 7 day larval period, a dense plexus of VIP-like immunoreactive fibe
rs first appeared in the olfactory bulbs. In 15-day-old larvae, two new gro
ups of positive cells were observed in the periventricular preoptic nucleus
and in the dorsal rhombencephalon. In 1 month/2 months old animals,VIP-lik
e immunoreactive elements were confined to the olfactory organ, the olfacto
ry bulbs, the periventricular preoptic nucleus and the pituitary, pars dist
alis. At 3 months stage, a large number of cells was observed in the perive
ntricular preoptic nucleus. Western immunoblot analysis confirmed that VIP-
like peptides, with molecular weight similar to that of synthetic VIP. are
present early during the development of zebrafish. These results show that
VIP-like immunoreactive structures appear early during ontogeny both in the
olfactory pit, retina and brain. Transient expression of positive cells wa
s found in the retina, telencephalon, diencephalon and brainstem. The locat
ion of VIP-like immunoreactivity indicates that, during development, VIP co
uld be involved in several neuromodulatory functions, including the process
ing of visual and olfactory informations, as well as growth or survival pro
motion activities. The presence of VIP-like immunopositive cells in the pit
uitary, pars distalis, suggest that, during development, VIP may influence
the secretion of pituitary hormones. (C) 2001 Elsevier Science B.V. All rig
hts reserved.