SRIF-like immunoreactivity in the brain and pituitary of Tinca tinca (Cyprinidae, Teleostei).

SRIF-immunoreactive perikarya occurred in the nucleus entopeduncularis, the nucleus praeopticus and praeopticus periventricularis, in the nucleus lateralis tuberis pars anterior, the nucleus ventromedialis, and in the nucleus posterior periventricularis. Additionally, SRIF-containing neurons were located in the nucleus dorsomedialis and dorsolateralis thalami. Weaklyimmunoreactive perikarya were found medially to the nucleus diffusus tori lateralis and in the rostral rhombencephalon, laterally to the fasciculus longitudinalis medialis, and dorsally to the fasciculus longitudinalis lateralis. SRIF-positive fibres could be found in the lateral and dorsal telencephalon, below most of the diencephalic nuclei, in the pituitary, the tectum opticum, the torus semicircularis, and in the lateral medulla oblongata.

Serotonin-immunoreactive neurons in the brain of Eigenmannia lineata (Gymnotiformes, Teleostei).

The distribution of serotonin-immunoreactive (5-HTi) neurons was determined by the peroxidase-antiperoxidase technique. 5-HT-immunoreactive nerve cells (or perikarya) occurred in the diencephalic nucleus ventromedialis (nvm), in the so-called pre-pacemaker nucleus (ppm), in a laterally located (unnamed) nucleus (G1), in the nucleus posterior periventricularis (nppv), the nucleus recessus lateralis (nrl) and the nucleus recessus posterior (nrp). 5-HT-immunoreactivity could be localized in the pars intermedia and the proximal pars distalis of the pituitary gland. Large 5-HTi perikarya were found in the lamina VI of the mesencephalic torus semicircularis (ts). Intensely immunostained 5-HTi perikarya occurred in the raphe region. 5-HT-immunoreactivity was also located in the medullary pacemaker nucleus of the specialized electric organ (pm). Only a few 5-HTi fibres were observed in the telencephalon. Ventral to the 3rd ventricle of the diencephalon between the caudal hypothalamic nuclei most of these were fibre bundles dorsal to the nuc. recessus lateralis. Some 5-HTi fibres traversed the pituitary stalk to the proximal pars distalis of the pituitary gland. Scattered 5-HTi fibres were seen in the torus semicircularis, lobus inferior (li) and cerebellum, while more fibres appeared in the medulla oblongata (mo) and below the pacemaker nucleus. The results are compared to those in other fish.

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)

FMRFamide-like immunoreactivity in the brain and pituitary of the teleost. Eigenmannia lineata (Gymnotiformes).

The distribution of cells immunoreactive for the molluscan tetrapeptide FMRFamide in the brain and the pituitary of Eigenmannia was investigated immunohistochemically by the use of the peroxidase-antiperoxidase (PAP) technique and unlabelled antibodies. FMRFi neurons were located in the ganglion of the nervus terminalis at the rostroventral side of the bulbus olfactorius. FMRFi perikarya were also found in a dorsomedial diencephalic nucleus, in the nucleus ventromedialis, in some liquor-contacting neurons of the nucleus lateralis tuberis and of the nucleus recessus lateralis and posterior. The perikarya of the midbrain pre-pacemaker nucleus were only weakly immunoreactive for FMRFamide while large FMRFi neurons (T-cells) occurred in lamina VI of the torus semicircularis, in the brain stem, in dorsal and medial layers of the lobus lineae lateralis posterior (LLLp) and in the medullary electric organ pacemaker nucleus (pm). FMRFi fibers and nerve endings were found in the bulbus olfactorius, in medial areas of the telencephalon, and rather densely in the rostral diencephalon. Ventrocaudally to most of the hypothalamic nuclei the occurrence of immunoreactive fibres increased; many coursed to the pituitary through the pituitary stalk. FMRFi fibres also appeared in the deep layers of the tectum opticum, in the torus semicircularis, in the medial and lateral medulla and below the pacemaker nucleus. Wherever FMRFamide-immunoreactivity occurred fibres and nerve endings could be found in close contact with blood vessels.

Distribution of somatostatin (SRIF) in the brain and pituitary of Eigenmannia lineata (Gymnotiformes, Teleostei). An immunohistochemical study.

Somatostatin-immunoreactive (SRIFi) cells in the brain and pituitary of the weakly-electric teleost Eigenmannia lineata were identified immunohistochemically by the use of unlabelled antibodies and the peroxidase-antiperoxidase technique. Several groups of neurons and fibres were immunostained in Eigenmannia's brain. Intensely SRIFi neurons occurred in the nucleus entopeduncularis, in the nucleus preaeopticus, and in the nucleus dorsolateralis between the commissura posterior and the nucleus glomerulosus, the latter two structures being completely devoid of immunoreactive elements. Few weakly-immunoreactive perikarya were found scattered in the nucleus ventromedialis and in the nucleus lateralis tuberis anterior and posterior. In the medullary electric organ pacemaker nucleus (pm) the large relay-neurons sometimes were immunoreactive while the smaller pacemaker-neurons were SRIF-negative and did not contain any immunoreactive vesicles. SRIFi fibres appeared in the dorsomedial and in the ventrolateral parts of the bulbus olfactorius. Telencephalic SRIFi fibres were found in the area dorsalis telencephali pars medialis below the ventricular wall and in the caudal pars lateralis. Diencephalic immunoreactive fibres were located below the preoptic nuclei, in the dorsomedial diencephalon, lateral to the nucleus dorsomedialis and ventromedialis, and as a bundle adjacent to the dorsomedial part of the nucleus recessus lateralis. SRIFi fibres coursing in the pituitary stalk led to the adenohypophysis. SRIFi mesencephalic fibres were only found in the rostral tectum opticum. In the anterior medulla oblongata SRIF-fibre-bundles occurred mediolaterally to the midline, and dorsolaterally below the lumen of the 4th ventricle. Only a few fibres were found in the corpus cerebelli, while an intensely immunostained medullary bundle occurred laterally to the pacemaker nucleus, connecting to the spinal medulla. The results of our study suggest that SRIF is a neurotransmitter or neuromodulator in the brain of Eigenmannia, also occurring in some parts of the electrosensory and electromotor system. The present results are compared to those in other teleost brains.

FMRFamide immunoreactivity in the brain and pituitary of Carassius auratus (Cyprinidae, Teleostei).

Neurons immunoreactive for the molluscan cardioactive peptide FMRFamide (FMRFi) in the brain of Carassius were demonstrated immunohistochemically with the peroxidase-antiperoxidase technique (PAP) and three antisera against this tetrapeptide. FMRFi perikarya were consistently found in the ganglion of the nervus terminalis, in some scattered neurons of the nucleus entopeduncularis, in the nucleus praeopticus pars magno- and parvocellularis, the nucleus ventromedialis, the nucleus posterior periventricularis, nucleus recessus lateralis and posterior. Some weak FMRFi neurons occurred in the rostral mesencephalic tegmentum and in the region of the nucleus gustatorius secundus. Both the medullary Mauthner neurons and the cerebellar Purkinje cells were only weakly immunoreactive for FMRFamide, while a group of intensely FMRFi rhombencephalic perikarya, presumably the nucleus motorius nervi vagi, occurred subependymally next to the fourth ventricle. FMRFi fibres and nerve endings occurred in the bulbus olfactorius, in the tractus opticus, and in the central parts of the dorsal, medial and ventral telencephalon. Some FMRFi fibres traversed through the commissura anterior while others occurred close to the hypothalamic nuclei, in the medial layers of the tectum opticum, in the brain stem, in the vagal lobe and in the ventral medulla oblongata. The present results are compared to the FMRFi structures in other fish brains.

FMRFamide-like immunoreactivity in brain and pituitary of Xenotaca eisenii: (Ciprinidontoformes, Teleostei).

FMRFamide-immunoreactive neurons were determined immunocytochemically by means of the PAP-technique for unlabeled antibodies. FMRFamide-containing perikarya were found in the frontoventral telencephalon, in the valvula and corpus cerebelli, and in the rostral and caudal medulla oblongata. FMRFamide immunoreactive cells were localized in the anterio lobe of the pituitary. FMRFamide fibres occurred in the bulbus olfactorius, in the anterior, medial and lateral parts of the telencephalon, in the commissura anterior, beneath the nucleus praeopticus, beneath the nucleus dorsomedialis, ventrolis and anterior tuberis as well as in the caudal hypothalamus, surrounding the nucleus recessus lateralis and posterior. In the mesencephalon, FMRF-amide-containing fibres appeared in the dorsal tegmentum, in the torus semicircularis and in the deep layers of the tectum opticum. In the rhombencephalon, only few fibres were found in the cerebellum but a strong innervation occurred in the ventrolateral and dorsolateral medulla oblongata. The present results are discussed with those of other teleost species.

Distribution of monoamine-containing neurons in the brain of a teleost, Carassius auratus (Cyprinidae).

The occurrence and distribution of monoamine-(MA) containing neurons and fibres in the brain of Carassius was investigated by formaldehyde-induced fluorescence (FIF) histochemistry (Falck-Hillarp technique). Many brightly green-fluorescent nerve cell perikarya were found in the nucleus dorsolateralis and ventromedialis, in the nucleus posterioris periventricularis, in the nucleus recessus lateralis and posterioris. They also occurred in the mesencephalic nucleus lateralis valvulae, in the metencephalic nucleus gustatorius secundus and near the ventricular borders of the facial and vagal lobes in the myelencephalon. Many fluorescent fibres and nerve terminals were localized in the frontal and medio-lateral parts of the telencephalon, showing fluorescent connections to the caudal parts. In the diencephalon, MA-fibres branched in a horizontal and ventral tract, leading to the medulla oblongata and the hypothalamic nuclei, respectively. There were laterally situated fibres connecting the hypothalamic nuclei with the medulla and the nucleus gustatorius secundus. Many fluorescent fibres were found in the middle layers of the tectum opticum, in the torus semicircularis, in the lobus inferior and in the medulla oblongata. Considerably fewer fibres occurred in the corpus cerebelli and in the dorsal parts of the hindbrain lobes. These results are compared with the MA-system in the brains of other fish.

Histochemical evidence for catecholamines as neurotransmitters in the statocyst of Octopus vulgaris.

Formaldehyde-induced fluorescence (Falck-Hillarp technique) provided histochemical evidence for the presence of catecholamines in the sensory epithelia (macula and crista) of the Octopus statocyst. A specific bright green fluorescence occurred in the neuronal plexus beneath the receptor cell layers of the epithelia and in the appropriate nerves. The histochemical findings are discussed with reference to the well-known neuronal and synaptic organization of the epithelia and to relevant results in cephalopods as well as in other molluscs. All data support the hypothesis that in the receptor systems of the Octopus statocyst catecholamines (probably dopamine and/or noradrenaline) act as neurotransmitters in the efferent fibre system.