Biomedical subjects

B Cozzi

Publications and source records attributed to B Cozzi.

At least 19 recordsLinked to original sources

PubMed2001

Sexual differences and effect of photoperiod on melatonin receptor in avian brain.

Several data suggest that melatonin may influence avian reproduction by acting at the level of the hypothalamic-hypophisial-gonadal axis, and/or on neural circuits controlling reproductive behaviours. The action of melatonin is exerted through specific receptors whose distribution and pharmacological properties have been extensively investigated. This review will focus on the distribution, sexual dimorphism, and dependence upon the photoperiod of melatonin binding sites in avian species with a special emphasis on Japanese quail. Melatonin receptors are widely distributed in avian brain. They are mostly present in the visual pathways of all the investigated species and in the song controlling nuclei of oscine birds. Sexual dimorphism of melatonin binding sites (higher density in males than in females) was detected in some telencephalic nuclei of songbirds, in the visual pathways, and in the preoptic area of quail. The last region plays a key role in the activation of male quail copulatory behaviour and it hosts a large population of gonadotropin-releasing hormone-containing neurons. Sexual dimorphism of melatonin-binding sites in the above-mentioned regions suggests a differential role for this hormone in the modulation of visual perception, gonadotropin production, and seasonally activated behaviours in male and female quail. Further studies are necessary to understand interrelationships among photic cues, gonadal steroids, density, and sexually dimorphic distribution of melatonin receptors.

Animals↗

PubMed2001

An overview of the central nervous system of the elephant through a critical appraisal of the literature published in the XIX and XX centuries.

The two species of elephants (Indian: Elephas maximus and African: Loxodonta africana) possess the largest brain among land mammals. Due to its size, the elephant brain is discussed in virtually every paper dealing with the evolution of the central nervous system of mammals and comparative brain size. Studies on the social habits of elephants also deal with the skills and the "intelligence" and brain size of these species. Yet most of the descriptions and conclusions reported in comparative studies rely on second-hand data derived from investigations performed several decades before, often dating as far back as the XIX century. Furthermore, many of the original papers actually describing gross and detailed features of the brain of elephants are either no longer available, are written in languages other than English, or are difficult to trace. The present study gives a short description of the anatomy of the central nervous system of elephants, with special attention to its distinctive features, reports all available literature on the subject, and briefly discusses its origins and rationale.

Animals↗

PubMed2000

The distribution of neuropeptide Y-immunoreactive neurons and nerve fibers in the forebrain of the carp Cyprinus carpio L.

The present study reports the distribution of Neuropeptide Y (NPY)-immunoreactive neurons and fibers in the forebrain of the adult carp Cyprinus carpio L. Serial Nissl-stained sections were used for cytoarchitecture and identification of anatomical structures. Immunostaining of NPY-containing neurons and fibers was used as neurochemical marker and tool for comparison with other species, including the goldfish. The general outline of the cytoarchitecture of the carp forebrain is similar to that of other Cypriniformes. However, using NPY immunohistochemistry, we found several specific differences with the goldfish, especially in the diencephalon. In the hypothalamus of the carp NPY-immunoreactive (NPYir) neurons were identified in the n. dorsolateralis thalami, and in the n. ventralis lateralis thalami. In the same location, we observed the n. anterior hypothalami and the n. preglomerulosus pars lateralis, described in the goldfish, as parts of n. prerotundus. However, in the carp we were not able to identify a n. preglomerulosus pars medialis, a n. preglomerulosus pars medialis commissuralis and a n. glomerulosus. We describe a n. rotundus, in which we did not find substructures typical of the goldfish. Further differences with the goldfish, trout and salmon were also noted.

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PubMed1999

Anatomic and surgical approach to the ethmoidal nerve and parasympathetic innervation of the nasal and cerebral circulation in sheep.

OBJECTIVE: To describe an anatomic and surgical approach to the efferent parasympathetic branches of the pterygopalatine ganglia in sheep, with particular reference to the ethmoidal nerve and innervation of nasal and cerebral blood vessels. ANIMALS: 12 adult sheep used for monolateral (n = 7) or bilateral (n = 5) ethmoidal neurectomy; 2 sheep used for angiography (1 live sheep for digital subtraction angiography, 1 embalmed cadaver for injection studies); and 5 embalmed cadavers, 4 frozen specimens, and 2 dry skulls used for dissection, x-rays, and computed tomographic (CT) or magnetic resonance (MR) scans. PROCEDURE: Transverse (coronal) MR scans, transverse, sagittal, and dorsal CT scans, radiography, angiography, photographic images, and dissections of embalmed material were used to study the topographic anatomy of the temporal and pterygopalatine fossae of the head. RESULTS: Images were stored, then compared with photographs of frozen sections from the same or a similar specimen to plan a surgical approach to the ethmoidal nerve. Mono- and bilateral experimental ethmoidal neurectomies were performed, allowing characterization of a safe and reliable method. The series of pterygopalatine ganglia typical of this species was localized, dissected, and analyzed for topographic relations. CONCLUSIONS: From the results, a new approach to the efferent branches of the pterygopalatine ganglia (ethmoidal nerve) for experimental parasympathectomy of the cerebral and nasal circle is proposed. This experimental approach could be used for studies involving thermoregulation of the face, and in experimental control of blood flow in the nasal cavity and rostral part of the brain.

Angiography, Digital Subtraction↗

PubMed1997

The NADPH-diaphorase-containing system in the brain of the budgerigar (Melopsittacus undulatus).

In the present investigation we studied the presence and distribution of histochemically detected neuronal NADPH-diaphorase (ND) in the brain of the budgerigar, Melopsittacus undulatus. Positive neurons are widely distributed throughout the central nervous system. ND-containing neurons are present in the telencephalon and the paleostriatal-parolfactory lobe complex. Positive cells were observed also in the neostriatum, including the main auditory area (field L), in several nuclei of the archistriatum and in the hyperstriatum (accessory, dorsal, and ventral). In the diencephalon, positive neurons were present both in the lateral hypothalamic and periventricular areas, and in a segregate area at the confluence of the anterior commissure and the lateral prosencephalic bundle. A group of positive perikarya was located lateral to the dorsal part of the IIIrd ventricle, and continued laterally into the thalamus. Weakly stained neurons were observed in the thalamic dorsomedial posterior nucleus. In the mesencephalon, ND-containing neurons were scattered in the reticular formation (pars lateralis and pars medialis) and in the optic tecta. A large population of positive neurons was observed in the substantia nigra, the ventral area of Tsai and the nucleus interpeduncularis. Positive neurons extended through the tegmental nuclei to the locus coeruleus. In the cerebellum, the granular neurons were weakly stained and the internal cerebellar nuclei were surrounded by a wide network of positive fibers. In the medulla the number of positive cells was highly reduced, but stained neurons were observed in the cochlear as well in the vestibular nuclei. The data here presented suggest that the distribution of ND-containing neurons in the brain of the budgerigar is different from those of the chicken and quail. The locations of positive neurons suggest also a possible involvement in sound perception and production pathways, and visual perception.

Animals↗

PubMed1997

Innervation of the sheep pineal gland by nonsympathetic nerve fibers containing NADPH-diaphorase activity.

We used the NADPH-diaphorase histochemical method as a potential marker for nitric oxide synthase (NOS)-containing nerve fibers innervating the pineal gland of the sheep. Nerve fibers containing NADPH-diaphorase activity provide dense innervation of the sheep pineal gland. The nerve fibers were located in the pineal capsule, in the connective tissue septae separating the lobull of the gland, and penetrating between the pinealocytes. The nerve fibers were either smooth or endowed with boutons en passant. After bilateral removal of the superior cervical ganglion, the dense network of NADPH-diaphorase-positive fibers was still present in the gland. Ganglionectomy affected neither the distribution nor the appearance of the NADPH-diaphorase-positive fibers. Most of the NADPH-diaphorase-positive fibers also contained peptide histidine isoleucine and vasoactive intestinal polypeptide, and a comparatively smaller fraction contained neuropeptide Y. Pinealocytes never exhibited NADPH-diaphorase activity. These results demonstrate a major neural input to the sheep pineal gland with NADPH-diaphorase-positive nerve fibers of nonsympathetic origin.

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PubMed1996

The chemical neuroanatomy of the mammalian pineal gland: neuropeptides.

The mammalian pineal gland contains multiple afferent peptidergic nerve fibres. Sympathetic nerve fibres, with their origin in the superior cervical ganglia, contain neuropeptide Y colocalized with norepinephrine. Other pinealopetal nerve fibres, probably originating in the pterygopalatine ganglion, contain vasoactive intestinal peptide and peptide histidine isoleucine. Fibres containing substance P and calcitonin gene-related peptide have also been demonstrated in pinealopetal nerve fibres. These fibres might originate in the trigeminal ganglion. The neurotransmitter content of the fibres of the central innervation, innervating the gland from the brain via the pineal stalk, has not been elucidated. However, strong indications for the presence of neuropeptide Y, substance P, somatostatin, and vasopressin in these fibres have been presented. Recent immunohistochemical studies have further shown the presence of subtypes of pinealocytes containing neuropeptides. Thus, pinealocytes containing beta-endorphin, leu-enkephalin, and somatostatin have been demonstrated in the gland. Immunohistochemistry at the electron microscopical level has shown, that in some species, leu-enkephalin containing pinealocytes make synaptic contacts with other pinealocytes indicating of paracrine regulation of the pineal gland. It must however be emphasized that large interspecies variations exist with regard to the peptidergic pineal innervation and its content of peptidergic cells.

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PubMed1996

Presence of nitric oxide synthase in the sheep pineal gland: an experimental immunohistochemical study.

By use of immunohistochemistry, a dense network of nerve fibres immunoreactive to the neuronal form of nitric oxide synthase (NOS, subtype I) was demonstrated in the pineal gland of sheep. The NOS-immunoreactive fibres were located in the pineal capsule and the connective tissue septae of the gland, but fibres were also present intraparenchymally between the pinealocytes. NOS-immunoreactive nerve fibres were still present in the gland 1 month after bilateral removal of the superior cervical ganglia. By use of an antibody directed against endothelial NOS (subtype III), only pineal blood vessels were stained. This staining was still present in the ganglionectomized animals. No difference was found in the staining between the control animals and the ganglionectomized ones. The pinealocytes were not stained, neither by the antibody against neuronal NOS nor by the antibody against endothelial NOS. By use of double immunohistochemical stainings, NOS was in many nerve fibres colocalized with vasoactive intestinal peptide. Western blot analysis of supernatant fractions of sheep pineal homogenates showed the presence of a band corresponding to the neuronal NOS. Thus, the present data show a prominent innervation of the sheep pineal gland with NOS-immunoreactive nerve fibres with their origin outside the sympathetic nervous system, indicating an influence of NO on the pinealocyte metabolism from non-sympathetic nerve fibres in this species. The presence of NOS in both perivascular nerve fibres and the endothelium of the blood vessels of the gland suggests a role of NO in the regulation of the circulation of the sheep pineal gland.

Animals↗

PubMed1994

The density of melatonin receptors is dependent upon the prevailing photoperiod in the Japanese quail (Coturnix japonica).

Two groups of Japanese quail (Coturnix japonica) were exposed to two different photoperiods (short and long days: LD 8:16 and LD 16:8, respectively), and their brains examined for the presence and distribution of melatonin receptors by means of quantitative in vitro autoradiography. Animals belonging to the LD 8:16 group expressed a significantly higher melatonin receptor density in the optic tectum and nucleus triangularis, while the LD 16:8 animals had a higher density of receptors in the hyperstriatum and nucleus preopticus dorsalis. These data demonstrate an apparent influence of the photoperiod on the density of melatonin receptors, especially in nuclei of the tectofugal pathway, related to the control of visual pattern and intensity discrimination, localization and orientation.

Animals↗

PubMed1994

Density of peptide histidine-isoleucine- and vasoactive intestinal peptide-immunoreactive nerve fibers in the sheep pineal gland is not affected by superior cervical ganglionectomy.

Peptide histidine-isoleucine (PHI) is a regulatory peptide, synthesized as part of the same propeptide that includes also vasoactive intestinal peptide (VIP). The present study describes the distribution of PHI-immunoreactive nerve fibers in the sheep pineal organ and compares their location with the distribution of VIP-immunoreactive fibers in both normal and superior cervical ganglionectomized sheep in order to elucidate the origin of the PHI/VIP immunoreactive nerve fibers. Several PHI-immunoreactive nerve fibers were present in the meninges and in the pineal capsule. Numerous positive nerve fibers entered the pineal gland and travelled within connective tissue spaces. Individual PHI-positive nerve fibers were either smooth, without specialization, or varicose. Generally VIP- and PHI-immunoreactive fibers were located close to connective septa and blood vessels. However, many PHIergic and VIPergic fibers possessing varicosities of variable sizes were also dispersed between pinealocytes. The distribution, density, and morphology of PHI- and VIP-immunoreactive fibers in the sheep pineal gland were similar. In superior cervical ganglionectomized animals, intrapineal VIP- and PHI-immunoreactive nerve fibers were present with the same density as in control animals. In agreement, the concentration of immunoreactive VIP and PHI did not change after ganglionectomy. No VIP- and PHI-immunoreactive cell bodies were observed in the superior cervical ganglia. Thus this study shows that the intrapineal VIP- and PHI-immunoreactive nerve fibers do not originate from the sympathetic superior cervical ganglion.

Animals↗

PubMed1994

Distribution of neuropeptide Y-like immunoreactivity in the hypothalamic tuberal nuclei of the immature gilts.

The distribution of neuropeptide Y in the immature female pig hypothalamic tuberal nuclei was investigated using avidin-biotin complex method. This study showed cell bodies containing NPY-immunoreactive material in the arcuate nucleus, dorsomedial and ventromedial nuclei, as well as internal layer of the median eminence and infundibulum, an observation not yet reported in the pig. NPY-immunoreactive fibers were noted throughout the hypothalamus, but most prominently within the periventricular region. Median eminence disclosed abundance of NPY-immunoreactive processes. The study shows a detailed organization of cell bodies and fibers containing NPY-immunoreactivity in tuberal hypothalamic nuclei of the immature gilts.

Animals↗

PubMed1993

Distribution and characterization of melatonin receptors in the brain of the Japanese quail, Coturnix japonica.

2-[125I]iodomelatonin was used to study the distribution and properties of the melatonin receptor in the Japanese quail brain. High receptor density was detected in the major targets of direct retinal input (optic tectum, nucleus of the optic basal rout, ventrolateral geniculate nucleus), as well as areas representing terminals in the visual pathways (nucleus rotundus, ectostriatum, thalamo-hyperstriatal pathway). Binding was also found in the piriform cortex, the hypophyseal pars tuberalis, the oculomotorius nucleus and the associated Edinger-Westphal nucleus, and in the nuclei of the third, fourth and sixth cranial nerves. A comparison of the receptor pharmacological profile to that of the mammalian brain demonstrated pharmacological identity of the two binding sites. In the saturation experiments, GPT gamma S decreased the binding affinity, numerical Kd values increasing from approximately 35 pM to approximately 150 pM.

Animals↗

PubMed1993

Autoradiographic localization of putative melatonin receptors in the brains of two Old World primates: Cercopithecus aethiops and Papio ursinus.

The distribution of putative melatonin receptors in the brains of two Old World primates of the superfamily Catarrhina, Cercopithecus aethiops and Papio ursinus, was characterized using 2-[125I]iodomelatonin autoradiography. The specific binding demonstrated a discrete distribution pattern. The median eminence was intensely labelled, and examination at the light microscopic level demonstrated that the binding was confined to the small layer of cells comprising the pars tuberalis of the pituitary gland. The collar of pars distalis, present in the baboon (Papio ursinus), was diffusely labelled. No binding was detected in the pars distalis proper or the neural lobe of the pituitary gland. The binding in the suprachiasmatic nuclei was weaker, but well discernible. Diffuse faint specific binding was found in the frontal cortex and the dentate gyrus of the hippocampus. Two non-neural sites expressed strong, well-delineated binding: the walls of some brain blood vessels (the vertebral and spinal arteries, the inferior cerebellar and acoustic arteries, the basilar, pericallosal, internal carotid arteries, the arteries forming the circle of Willis) and the choroid plexuses. Binding in the arteries of the circle of Willis, the pars tuberalis and the suprachiasmatic nuclei was readily displaceable. Addition of 1 microM unlabelled 2-iodomelatonin following 45 min of preincubation with the radioactive ligand completely abrogated the binding. Co-incubation with guanosine 5'-O-(3-thiotriphosphate) led to a significant decrease in the apparent binding density in the pars tuberalis and abolished binding in the suprachiasmatic nuclei, but was without effect on the binding in the walls of the adjacent arteries, forming the circle of Willis, in the cortex and in the hippocampus. This qualitative distribution pattern demonstrates that in the two primate species studied, melatonin high-affinity, G-protein-linked binding sites are present in the pars tuberalis and the hypothalamic suprachiasmatic nuclei, and that melatonin may be acting as a synchronizer of the endogenous pacemakers' circadian activity, apart from its possible reproductive effects at the level of pars tuberalis, where the highest receptor density was observed. The strongly labelled arterial walls, and the flimsy labelled cortex and hippocampus, expressed different characteristics: though the binding was readily reversible, it was apparently not regulated by a guanine nucleotide-binding protein.

Animals↗

PubMed1992

Neuropeptide Y (NPY) and C-flanking peptide of NPY in the pineal gland of normal and ganglionectomized sheep.

The present immunohistochemical study describes the presence and distribution of nerve fibers containing neuropeptide Y (NPY), and C-Flanking Peptide Of NPY (CPON) in the pineal gland of the sheep. Nerve fibers were detected by using a series of antisera directed against NPY or against CPON. Many positive immunoreactive nerve fibers were identified in the pial capsule of the pineal, in connective septae and in the parenchyma between pinealocytes. The intraparenchymal fibers were particularly evident and created an extensive network throughout the gland. Nerve fibers immunoreactive for all the peptides were also observed in the posterior commissure and in the stria medullaris thalami. No NPY- or CPON-positive neurons were found in the pineal gland. In order to study the site of origin of NPY- and CPON-immunoreactive nerve fibers, the superior cervical ganglia were bilaterally removed in a series of animals. Sympathetic denervation was checked by using an antiserum against tyrosine hydroxylase (TH). Nearly all TH-immunoreactive elements disappeared in the pineal glands of animals sacrificed 15 days after surgery. Also the density of NPY- and CPON-immunoreactive nerve fibers decreased in the animals after the ganglionectomy. However, a number of nerve fibers still remained in the gland. These data indicate that some NPY- and CPON-immunoreactive nerve fibers of the sheep pineal gland derive from an extrasympathetic origin. The very dense innervation of the sheep pineal gland with nerve fibers containing NPY and CPON strongly indicates a functional role for this family of peptides in the pineal gland of this species.

Animals↗

PubMed1992

The protein-phosphatase inhibitor okadaic acid mimics MSH-induced and melatonin-reversible melanosome dispersion in Xenopus laevis melanophores.

The present study describes the ability of 315 nM okadaic acid to induce melanosome dispersion in cultured Xenopus laevis melanophores. This effect of okadaic acid is similar to that of a-melanocyte stimulating hormone (MSH) and can be reversed by melatonin treatment; it indicates that a member of the protein-phosphatase 1 or 2A families must be active for maintenance of the aggregated state. Higher concentrations of okadaic acid (1 microM) attenuate the response of Xenopus melanophores to melatonin leading to the hypothesis that melatonin action is mediated by the calcium/calmodulin activated phosphatase 2B. This hypothesis seems unlikely, however, since the calcium/calmodulin inhibitors TFP and W7 do not prevent melatonin-induced pigment aggregation, but instead induce aggregation on their own.

Animals↗

PubMed1992

Regulation of the androgen receptors in the harderian gland of the male Syrian hamster: influence of photoperiod, castration, and chronic melatonin treatment.

Male Syrian hamsters that were exposed for 8 weeks to short photoperiod (LD 10:14) or treated with melatonin in the late afternoon under long photoperiod conditions (LD 14:10) had a significantly higher content of androgen receptors in the Lipidex-purified soluble fractions isolated from the Harderian glands as compared to the long photoperiod (LD 14:10) exposed controls. Simultaneous computer-assisted analyses of all series of saturation and competition experiments revealed that the numerical value of the apparent Kd, as determined by using the synthetic androgen R-1881 (methyltrienolone), was not different between the experimental groups, and ranged from 0.050 to 0.067 nM. Of the principal natural androgens, testosterone (T) was most potent in inhibiting methyltrienolone binding to the receptor (Ki values from 0.33 to 0.55 nM), and 5 alpha-dihydrotestosterone (DHT) and delta 4-androstenedione (AD) were less effective (Ki values between 1 and 1.9 nM). In the hypothalami and pituitaries of the same animals, used in parallel control assays, DHT was twice as potent as T. Short-term castration (24 hr post-orchidectomy) did not result in significant changes in the receptor binding characteristics. Following 8 weeks exposure to a long photoperiod (LD 14:10) the Bmax values demonstrated a four-fold increase in castrated animals (179 fmoles/mg protein vs. 47 fmoles/mg protein) over intact controls. The relative binding affinity of the major androgens under these conditions remained unchanged, with the exception of AD, where a five-fold increase in the numerical Ki values (decrease in the binding affinity) was recorded (Ki = 9.6 nM).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1992

Melatonin signal transduction and mechanism of action in the central nervous system: using the rabbit cortex as a model.

The cortex of the rabbit (Oryctolagus cuniculus) is rich in melatonin binding sites, and particularly abundant is the parietal cortex. Consequently, we characterized the putative melatonin receptor in the parietal cortex by a series of in vitro ligand-receptor binding experiments and biochemical and electrophysiological studies. The in vitro saturation and competition experiments demonstrated that the binding in the crude cortical membrane preparations was of high affinity and specificity. Guanine nucleotides (GDP, GTP, and GTP gamma S) inhibited the specific 2-[125I]iodomelatonin binding in a dose-dependent manner. Coincubation with a nonhydrolyzable GTP analog provoked a shift in the binding affinity; the numerical values of the Kd increased from 20-30 to 200-600 pM. Melatonin, in nanomolar concentrations, was able to inhibit the forskolin-stimulated accumulation of cAMP in parietal cortex explants, and preincubation with pertussis toxin counteracted this effect of melatonin. Apparently, the melatonin binding site in the rabbit parietal cortex is linked to its second messenger via a pertussis toxin-sensitive G-protein, probably of the inhibitory Gi class, similar to what has been described for different parts of the brain of other vertebrates. The experiments on the spontaneous firing activity of single neurons in the third to fourth layer of the parietal cortex in anesthetized animals showed that melatonin and its potent agonist 2-iodomelatonin exhibited gamma-aminobutyric acid (GABA)-like effects and were able alone, in nanomolar concentrations, to significantly slow the neuronal firing activity. Moreover, both melatonin and 2-iodomelatonin potentiated the effect of GABA on the neuronal activity, leading to powerful inhibition of the tested neurons. Undoubtedly, the binding site in the rabbit parietal cortex possesses all of the characteristics of a functional receptor. We suggest that melatonin is involved in the control of fundamental cortical functions and that it acts in concert with GABA, one of the two major inhibitory neurotransmitters in the central nervous system.

Animals↗

PubMed1991

Localization and characterization of melatonin binding sites in the brain of the rabbit (Oryctolagus cuniculus) by autoradiography and in vitro ligand-receptor binding.

The distribution and the properties of the melatonin binding sites were characterized in the brain of the rabbit by combined use of autoradiography and in vitro ligand-receptor binding. Autoradiography revealed widespread specific binding in the brain. The pars tuberalis of the pituitary gland, suprachiasmatic nuclei, ventromedial hypothalamic nuclei, tapetum, hippocampus, indusium griseum, cingulate gyrus, cortex and the choroid plexus were intensely labelled. Diffuse specific binding was recorded in the olfactory bulb and the anterior hypothalamus. Series of in vitro ligand-receptor binding experiments, using the anterior hypothalamus, confirmed that the binding was of high affinity and specificity. Coincubation with a non-hydrolyzable GTP analogue provoked a shift in the binding affinity, the numerical values of the Kd increasing from 20-30 pM to 280-300 pM. Apparently the melatonin receptor in the rabbit brain is linked to its second messenger via a G protein, similarly to what has been described for the brain of other vertebrates.

Animals↗