NPY-like immunoreactivity in the brain of the teleost Tinca tinca (Cyprinidae).

The distribution of neuropeptide tyrosine (NPY) in the brain of the tench (Tinca tinca) was mapped immunohistochemically by the peroxidase-anti-peroxidase (PAP) technique. NPY-immunoreactive (NPYi) neurons were found in the nucleus entopeduncularis (ne). These perikarya were intensely immunostained and were surrounded by a large number of axons and fibre terminals. Additional immunoreactive neurons appeared in the nucleus dorsolateralis thalami (ndl) at the level of the commissura posterior (cp). Only a few scattered NPY-positive perikarya occurred in the nucleus ventromedialis (nvm) and in the nucleus posterior periventricularis (nppv). At more caudal levels immunoreactive NPY-neurons were found in the nucleus lateralis valvulae of the dorsal tegmentum mesencephali. Besides some scattered neurons in the medulla oblongata the only immunostained neurons were located in a subependymal nucleus at the lateral border of the fourth ventricle. However, these perikarya were only weakly immunostained by the NPY-antiserum. From its location this cell group is considered as nucleus motorius nervi vagi (nmX). NPYi fibres and axon terminals were found in the bulbus olfactorius, in the dorsal and lateral areas of the telencephalon, in the near surrounding of the ne, below most of the hypothalamic nuclei, as a connection between the nucleus posterior periventribularis and the nucleus recessus lateralis, in the ventral hypothalamus, in the lateral parts of the pituitary and in the caudal diencephalic inferior lobe. NPY-fibres occurred in the medial and deep layers of the tectum opticum, in the marginal areas of the tegmentum and the torus semicircularis, and as a lateral fibre tract through the medulla oblongata, connecting to the rostral parts of the spinal cord.(ABSTRACT TRUNCATED AT 250 WORDS)