Calretinin immunoreactivity in the brain of the zebrafish,Danio rerio: Distribution and comparison with some neuropeptides and neurotransmitter-synthesizing enzymes. I. Olfactory organ and forebrain

Abstract

The distribution of calretinin (CR) in the forebrain and the olfactory system of the adult zebrafish was studied by using immunocytochemical techniques. Previous studies in trout forebrain have indicated that CR-immunoreactive neurons acquire this phenotype rather early in development (Castro et al., J. Comp. Neurol. 467:254-269, 2003). Thus, precise knowledge of CR-expressing neuronal populations in adult zebrafish may help to decipher late stages of forebrain morphogenesis. For analysis of some forebrain nuclei and regions, CR distribution was compared with that of various ancillary markers: choline acetyltransferase, glutamic acid decarboxylase, tyrosine hydroxylase, neuropeptide Y, thyrotropin-releasing hormone, and galanin. The results reveal that calretinin is a specific marker of olfactory receptor neurons and of various neuronal populations distributed throughout the telencephalon and diencephalon. In addition, CR immunocytochemistry revealed characteristic patterns of fibers and neuropil in several telencephalic and diencephalic regions, indicating that it is a useful marker for characterizing a number of neural centers, pathways, and neuronal subpopulations in the zebrafish forebrain. Some ancillary markers also showed a distinctive distribution in pallial and subpallial regions, revealing additional aspects of forebrain organization. Comparison of the distribution of CR observed in the forebrain of zebrafish with that reported in other teleosts revealed a number of similarities and also some interesting differences. This indicates that various neuronal populations have maintained the CR phenotype in widely divergent teleost lines and suggests that CR studies may prove very useful for comparative analysis.

How Neuronal Migration Contributes to the Morphogenesis of the CNS: Insights from the Zebrafish

“…At 1 month the morphology of the GFP+ cells is well developed ( fig. 3 A, inset) and resembles that of dorsal telencephalic interneurons detected by other authors with GAD immunohistochemistry [Castro et al, 2006a].…”

Early development of the nervous system of the eutherian <i>Tupaia belangeri</i>

“…Most probably, these cells represent invading basophils . Interestingly, a complex innervation pattern of FMRFamide-immunoreactive fibers was also found in the brain of Salmo trutta fario and, here, included moderate amounts of FMRFamide-labelled fibers in the pituitary gland (Castro et al, 2001).…”

Stalking the Everted Telencephalon: Comparisons of Forebrain Organization in Basal Ray-Finned Fishes and Teleosts

“…In Anguilla , the messenger RNA for the dopamine D 1A2 receptor subtype -characteristic of the mammalian lateral (olfactory) pallium -is found in Dp but not in Dl [Kapsimali et al, 2000]. Additionally, in Danio , Dp displays high levels of tyrosine hydroxylase fibers, whereas Dl does not; the reverse is true for neuropeptide Y [Castro et al, 2006]. Thus Dp might well constitute a separate pallial zone.…”