The endocannabinoid system in the brain of Carassius auratus and its possible role in the control of food intake.

Cannabinoid receptors and the endocannabinoids anandamide and 2-arachidonoylglycerol have been suggested to regulate food intake in several animal phyla. Orthologs of the mammalian cannabinoid CB(1) and CB(2) receptors have been identified in fish. We investigated the presence of this endocannabinoid system in the brain of the goldfish Carassius auratus and its role in food consumption. CB(1)-like immunoreactivity was distributed throughout the goldfish brain. The prosencephalon showed strong CB(1)-like immunoreactivity in the telencephalon and the inferior lobes of the posterior hypothalamus. Endocannabinoids were detected in all brain regions of C. auratus and an anandamide-hydrolysing enzymatic activity with features similar to those of mammalian fatty acid amide hydrolase was found. Food deprivation for 24 h was accompanied by a significant increase of anandamide, but not 2-arachidonoylglycerol, levels only in the telencephalon. Anandamide caused a dose-dependent effect on food intake within 2 h of intraperitoneal administration to satiated fish and significantly enhanced or reduced food intake at low (1 pg/g body weight) or intermediate (10 pg/g) doses, respectively, the highest dose tested (100 pg/g) being inactive. We suggest that endocannabinoids might variously contribute to adaptive responses to food shortage in fish.

Environmental estrogens and reproductive biology in amphibians.

In this paper, the effects of an estrogenic compound, 4-nonyl-phenol (NP), on the amphibians Rana esculenta and Triturus carnifex are described together with those on sexual differentiation in Xenopus laevis. NP increased plasma vitellogenin in male frogs and newts in a dose-related manner; moreover, inhibitory effects on gonadotropin and prolactin (PRL) secretion by pituitary were found together with an elevation of plasma androgens. NP treatment also caused a remarkable increase in number of prolactin-immunolabeled cells, suggesting that xenoestrogen might induce, at least in the newt pituitary, a PRL accumulation possibly due to a reduction of the hormone release. In addition, both NP and bisphenol A caused feminization by increasing the percentage of female phenotypes in X. laevis, and the in vivo effects were more pronounced than those of estradiol-17beta.

Relationships between neuronal cell adhesion molecule and LHRH neurons in the urodele brain: a developmental immunohistochemical study.

Polysialic acid (PSA), a homopolymer attached to neural cell adhesion molecule (NCAM) is considered a major hallmark of vertebrate cell migration. We studied the distribution of PSA-NCAM by immunohistochemistry, during brain development, in two urodele amphibians, Pleurodeles waltl and the neotenic newt Ambystoma mexicanum. In both species a gradual increase of immunolabelling was observed throughout the brain from developmental stage 30 to stage 52. At the onset of metamorphosis, some differences became evident: in Pleurodeles immunostaining was gradually restricted to the olfactory system while in Ambystoma, PSA-NCAM maintained a more extended distribution (for example throughout the telencephalic walls) suggesting, for the brain of this latter species, a rather preserved neuronal plasticity. The aim of the present work was to correlate the above described PSA-NCAM-immunoreactivity (IR) with the distribution of luteinizing hormone-releasing hormone (LH-RH) containing neurons, which represent a well known example of neural elements migrating from the olfactory placode. LHRH-IR, undetectable till stage 30, was later found together with PSA-NCAM-IR in both the olfactory system and septo-hypothalamic areas. Such observations further support a role of PSA in providing a migration route toward the establishment of a part, at least, of the urodele LHRH system. The possible functional meaning of the LHRH-containing neurons localized between dorsal and ventral thalamus of Ambystoma, never reported before in this area, almost devoid of PSA-NCAM-IR, is discussed.

Connections of the posterior pallium in the crested newt, Triturus carnifex.

The connections of the posterior pallial regions were studied in the crested newt, Triturus carnifex, by means of the horseradish peroxidase technique. The tracer was injected into the lateral and medial pallia, caudal to the interventricular foramen. In addition, the connections between the posterior pallium and the infundibular hypothalamus were investigated with both horseradish peroxidase and the fluorescent dye DiI. The results show important differences between the connection patterns of the medial and lateral pallia. The lateral pallium receives inputs from the main olfactory bulb and send fibers to the contralateral hemisphere through the anterior commissure. It also shows modes extra-telencephalic connections. Conversely, the medial pallium receives direct afferent inputs from the amygdala (pars medialis) and the anterior dorsal thalamus. It is reciprocally connected to the contralateral homologue region through the hippocampal commissure, and its main efferent system is the medial forebrain bundle, which reaches the infundibular hypothalamus. The infundibulum also receives a prominent projection from the amygdala (pars lateralis). The connectivity of the posterior pallium is comparable to that reported previously for the anterior pallium, although a few differences are noted. These differences in the connectivity of the lateral pallium and the medial pallium may reflect different functional properties of these telencephalic regions.

The neuroanatomic binding pattern of [125I]atrial natriuretic factor in the Japanese quail brain.

Application of quantitative autoradiography technique provided a discrete anatomical distribution pattern of the atrial natriuretic factor (ANF) in the Japanese quail, Coturnix coturnix japonica, brain. The highest binding levels of [125I]ANF were shown to occur in telencephalon areas, such as fasciculus diagonalis Brocae (232 fmol/mg protein), septum (194 fmol/mg protein) and olfactory bulb (153 fmol/mg protein), and in posterior sites, such as nucleus interpeduncularis (177 fmol/mg protein), while lower levels (> 51 < 87 fmol/mg protein) were found in the hypothalamic sites of the diencephalon. The similar ANF receptor density levels in some brain areas of the quail as well as both mammalian and non-mammalian species suggest that this peptide might be involved in osmoregulatory activities (at the brain level) and furthermore indicate a probable functional conservation of ANF in vertebrates.

Brain natriuretic peptide (BNP)-like immunoreactivity in the central nervous system of the crested newt.

The distribution of brain natriuretic peptide (BNP)-like immunoreactivity (ir) was studied in the brain of a urodele amphibian, the crested newt Triturus carnifex Laur. BNP-like immunoreactive neurons were found mainly in the caudal hypothalamus (retro- and supra-chiasmatic areas) and in the preoptic area. A widespread innervation throughout the brainstem as far as the spinal cord was also observed. By double immunostaining (after section incubation with a-BNP and a-tyrosine hydroxylase-TH-antibodies), close topographical relationships between BNP-like and TH-like immunoreactive neurons within the hypothalamus were found.

Tyrosine hydroxylase-immunoreactive neurons in the hypothalamus of the crested newt. An electron microscopic study.

The fine structure and specialized neuronal, vascular and ventricular relations of tyrosine hydroxylase (TH)-immunopositive neurons and processes were examined in the hypothalamus of the crested newt. TH-immunoreactive neurons form a well developed system. Its possible role in the hypothalamic neuroendocrine mechanisms is discussed.

A Golgi study on the neuronal morphology in the hypothalamus of the Japanese quail (Coturnix coturnix japonica). I. Tuberal and mammillary regions.

Neuronal morphology and dendritic architecture of the tuberal and mammillary regions in the hypothalamus of the quail (Coturnix coturnix japonica) were investigated by means of classical neuroanatomical methods (Bodian silver impregnation, Luxol-fast blue, cresyl violet, toluidine blue, rapid Golgi method). The tuberal region is characterized by isodendritic neurons, in particular: a) pyriform and bipolar neurons, occasionally arranged diagonally to the ventricular surface; b) CSF-contacting neurons, located subependymally or more deeply in the periventricular gray, which are especially abundant in the paraventricular organ and in the proximity of the median eminence; c) numerous multipolar neurons, endowed with stout, almost unbranched dendritic processes, occupying generally the medio-lateral areas of the hypothalamus. Some multipolar neurons display somata, pyramidal or ovoidal in shape, almost imperceptibly tapering into three or more dendritic trunks. These relatively straight and long dendrites are rich in dendritic spines. In the mammillary region, Golgi impregnation shows multipolar neurons of medium size, most likely belonging to the lateral mammillary nucleus.

The hypothalamus of Lacerta sicula R. II. A Golgi study of the preoptic area.

An analysis of the preoptic area of the lizard, Lacerta sicula R., with the use of the Golgi method revealed that: 1) in principle, the dendritic pattern of its neurons is relatively simple; 2) the supraoptic nucleus contains large- to medium-sized bipolar or multipolar neurons together with small, usually multipolar nerve cells; 3) the preoptic periventricular gray and the paraventricular nucleus exhibit a varied neuronal typology, including large multipolar or bipolar elements, abundant CSF-contacting neurons and some tufted elements; and 4) the lateral regions display some conspicuous multipolar neurons.

Ultrastructural analysis of the posterior hypothalamus of salamander.

The anatomical organization of the tuberal area of th posterior hypothalamus in Salamandra was investigated by the Golgi methods, SEM and TEM techniques. The ependymal cells of this area are poor in cilia and often show morphological features of actively secreting or absorbing elements. Intermingled with ependymal cells, two kinds of CSF-contacting processes are seen, arising from neurons of the periventricular grey. Their contents and morphological characteristics allow them to be divided into two groups, A and B. In the neuropil different synaptic contacts are seen. The observation of unconventional synaptic contacts possibly of axo-axonic type suggests the occurrence of local circuits on the final neurosecretory pathway.

The hypothalamus of Lacerta sicula R. I. A Golgi study on the caudal hypothalamus.

The posterior (caudal) hypothalamus of the lizard, Lacerta sicula R. was investigated by means of Golgi methods. The periventricular grey is formed mainly by isodendritic bipolar and multipolar neurons, while in the lateral hypothalamus a more stellate form of neuronal elements is encountered. CSF-contacting neurons are restricted to the tuberal area and to the paraventricular organ. In the latter area they are highly differentiated and endowed with laterally branched processes. The overall pattern of the lizard hypothalamus (organization of neuropil, lateral nuclei, appearance of cell clusters, morphology of the neuronal elements) represents an intermediate stage in the phylogenetic development of the hypothalamus, being more advanced than the amphibian stage.

A Golgi study of the hypothalamus of Actinopterygii. II. The posterior hypothalamus.

The posterior hypothalami of the polypteriform, Calamoichthys, and of the teleost, Anguilla, were studied by means of the Golgi technique. In Calamoichthys, the lateral lobes are not developed and the median lobe is simple. In Anguilla, the median (tuberal) lobe shows lophodendritic, CSF-contacting cells and horizontal cells in the periventricular grey and some reticular elements directed toward the cell-poor lateral areas. In the lateral lobes the periventricular grey is formed by multipolar neurons and a diffuse population of multipolar cells of uncertain identity. The nucleus diffusus lobi lateralis is formed by scarce multipolar neurons, often placed next to the external surface of the brain. The organization of the lateral lobes in Actinopterygii is reminiscent of highly developed integrative regions.

A Golgi study of the hypothalamus of actinopterygii.

The preoptic area of a primitive actinopterygian, the polypteriform, Calamoichthys calabaricus Smithi, and of the teleost, Anguilla anguilla L., have been studied by Golgi and other neurohistological and histochemical methods. In the preoptic area two regions can be recognized: a cell rich median region and a lateral one, composed mostly of fiber systems. After Golgi staining a varied population of neurons is seen, including: (1) magnocellular neurons, endowed with a number of dendrites and an axon emerging from the main dendritic shaft; (2) lophodendritic tufted or pyriform neurons of variable morphology (often of the midget type); (3) cerebrospinal fluid contacting neurons; (4) bipolar and horizontal neurons. Of relevant interest is also the observation of commissural neurons, of a distinct precommissural necleus, and of bipolar neurons, the axons of which course toward the ventral hypopallium.

A Golgi study on the hypothalamus of amphibia. The neuronal typology.

The neuronal typology in the hypothalamus of the frog and the crested newt was studied by the Golgi technique. In the newt, piriform, multipolar or cerebrospinal fluid (CSF)-contacting neurons of relatively primitive type, according to the classification of Ramón-Moliner, are encountered in the preoptic area. Moreover, magnocellular neurons are impregnated. In the frog the preoptic area shows a more varied typology. The posterior hypothalami of the frog and the newt exhibit mainly bipolar CSF-contacting and piriform neurons. These latter are generally "tufted", but some bipolar of multipolar cells are encountered, especially in the frog. The simple anatomical organization of the amphibian hypothalamus corresponds well with the pattern of "generalized" integrative area where multimodal sensory inputs converge--including visceral information from cerebrospinal fluid by means of hypothalamic CSF-contacting sensors--to regulate the neuroendocrine outflow.