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1. MORPHINE WITHDRAWAL-INDUCED SPINE DENSITY DECREASE IN THE NUCLEUS ACCUMBENS: SELECTIVE LOCALIZATION IN SECONDARY DENDRITES OF MEDIUM SPINY NEURONS.
No full textMorphine withdrawal-induced morphological changes in the nucleus accumbens
No full textMorphine withdrawal produces a hypofunction of mesencephalic dopamine neurons that impinge upon medium spiny neurons (MSN) of the forebrain. After chronic treatment (from 20 to 140 mg/kg of morphine twice a day over 14 days at escalating doses) rats were withdrawn from chronic morphine spontaneously and pharmacologically. In these two distinct conditions we studied the effects of withdrawal on the morphology of MSN of the core and shell of the nucleus accumbens (Nacc). MSN were stained with the Golgi–Cox procedure and analysed by a confocal laser-scanning microscope (CLSM). Our analysis shows that, shell and core MSN differed significantly for perikarya size and spine density, and the various morphine treatments did not affect the perikarya morphometry. Both spontaneous and naloxone-induced withdrawal produced a similar reduction in spine density in MS shell neurons, as compared with MS core neurons. This effect is selectively localized at the level of second order dendritic trunks where afferents converge. By contrast, spine density counts of accumbens MSN from rats chronically treated with morphine, did not reveal any change. Collectively, the results of the present study are twofold: (i) spontaneous and pharmacologically precipitated withdrawal, but not chronic morphine per se, affects spine density of target structures of a reduced mesolimbic dopamine transmission, and (ii) the reduction of spine density in second order dendritic trunks is selectively segregated in the MSN of the shell of the Nacc. In conclusion, morphine withdrawal dramatically alters spine density, selectively in second order dendritic trunks of Nacc shell MSN, thereby further impoverishing the already abated dopamine (DA) transmission. This is in line with recent views suggesting the hypodopaminergic state as a cardinal feature of opioid dependence
MORPHINE WITHDRAWAL-INDUCED ABNORMALITIES IN THE VTA: CONFOCAL LASER SCANNING MICROSCOPY.
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1. EVIDENZIAZIONE DELLE FIBRE VAGALI AFFERENTI SENSITIVE ALLE INSULE DI LANGERHANS NEL RATTO TRAMITE INIEZIONE DI BIOCITINA
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Astroglial in vivo response to cocaine in mouse dentate gyrus: a quantitative and qualitative analysis by confocal microscopy
No full textAstrocytes have been proved to play a critical role in neuromodulation, neuroprotection, pH maintenance, axon guidance control during development, homeostasis preservation and blood brain barrier maintenance in the CNS (Kimmelberg and Norenberg, 1989). Quantitative changes in the expression of glial fibrillary acidic protein (GFAP), a cytoskeletal intermediate filament protein exclusively expressed in astrocytes (Bignami et al., 1972), have been observed after administration of alcohol (Franke, 1995), morphine (Beitner-Johnson et al., 1993), amphetamine and its derivates (Aguirre et al., 1999), cannabinoids (Suarez et al., 2000), nicotine (Janson and Moller, 1993), caffeine (Marret et al., 1993) and prenatal exposure to cocaine (Clarke et al., 1996; Nassogne et al., 1998). However, the general astrocytic response to drugs of abuse is still far from being defined. In the present study we examined the in vivo astroglial response to cocaine in mouse dentate gyrus, the hippocampus being a common target of neurotoxic agents (Walsh and Emerich, 1988) which has a prominent effect on learning and memory processes (Eichenbaum. et al., 1992). Quantitative changes in immunoreactivity of GFAP were investigated 24 h after acute and repeated daily administraion of intraperitoneal cocaine (20 mg/kg). Drug-induced morphological alterations and spatial distribution of astrocytes were evaluated by means of confocal microscope. The results show that, compared to control animals, GFAP expression is two-fold enhanced after a single cocaine injection, still significantly higher after seven consecutive daily administrations, but not statistically different after prolonged (14 days) drug treatment. Moreover, morphological and morphometric analyses reveal significant modifications in astrocytic numbers, cell size and shape complexity. These data demonstrate that in mouse dentate gyrus, cocaine exposure differently affects the expression of GFAP and induces strong changes in astrocytes proliferation rate and cell morphology. Taken together, our findings provide the first in vivo quantitative and qualitative evaluation of astrocytic response to several regimens of cocaine in adult animals brain. (C) 2002 IBRO. Published by Else-vier Science Ltd. All rights reserved
A structural study of the optic nerve of Hydromantes genei
No full textThe structure of the optic nerve of Hydromantes genei, was investigated by confocal laser scanning microscopy and by the Cajal-De Castro method. This nerve appears to be composed of unmyelinated fibres, which is a rare case in amphibians. In view of this and the fact that it contains a relatively small number of nervous fibres, the optic nerve of N. genei, in comparison with other species of Plethodontidae, can be considered a structure with a low level of complication
Use of biocytin as neuroanatomic tracer in harvested human pancreas: a confocal laser scanning microscopy analysis
No full textINTRODUCTION:
To identify central neuroanatomic structure, biocytin labeling has recently been used. To date, there are no bibliographic references about the use of this molecule in investigations of the peripheral nervous system. In the present study, fresh, harvested human pancreas was used to evidence pancreatic innervations by biocytin.
AIM:
To investigate for the first time pancreatic innervation in harvested pancreas from human multiorgan cadaveric donors.
METHODOLOGY:
Biocytin labeling was used as a neuroanatomic tracing method, and confocal laser scanning microscopy was used for analysis for description by means of high-resolution images.
RESULTS:
The application of biocytin-avidin staining in harvested human pancreas revealed numerous bundles of nervous fibers, intrapancreatic ganglia, few small solitary neurons, and a large number of positive supporting cells (glial-like cells). Biocytin appeared to pass through gap junctions between glial elements and neurons and among the neurons. In human pancreas, biocytin is rapidly transported in both anterograde and retrograde directions, with consequent visualization of fine details of pancreatic innervation morphology. Indeed, evidence of anterograde and retrograde transportation of biocytin has been demonstrated in the extensive labeling of pancreatic preganglionic and postganglionic fibers as well as a great number of chemical buds that wind through exocrine tissue or undetermined target cells.
CONCLUSION:
To our knowledge, this is the first report of the successful use of biocytin in neuronal retrograde and anterograde labeling in the human peripheral nervous system
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