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  • Electronic Resource  (4)
  • Electron microscopy  (2)
  • Radial-arm maze  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Psychopharmacology 119 (1995), S. 282-290 
    ISSN: 1432-2072
    Keywords: Radial-arm maze ; Δ9-tetrahydrocannabinol (Δ9-THC) ; CP-55,940 ; WIN-55,212-2 ; Anandamide ; Cannabidiol ; Hippocampus ; Antinociception ; Catalepsy ; Rectal temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The purpose of the present study was to investigate the disruptive effects of cannabinoids on working memory as assessed in the eight-arm radial-maze. Systemic administration of Δ9-THC, WIN-55,212-2, and CP-55,940 increased the number of errors committed in the radial-maze. CP-55,940 was the most potent cannabinoid in impairing memory (ED50=0.13 mg/kg). Δ9-THC and WIN-55,212-2 disrupted mazechoice accuracy at equipotent doses (ED50 values =2.1 and 2.2 mg/kg, respectively). In addition, systemic administration of each of these agents retarded completion time. Whereas the doses of Δ9-THC and CP-55,940 required to retard maze performance were higher than those needed to increase error numbers, WIN-55,212-2 was equipotent in both of these measures. On the other hand, neither anandamide, the putative endogenous cannabinoid ligand, nor cannabidiol, an inactive naturally occurring cannabinoid, had any apparent effects on memory. A second aim of this study was to elucidate the neuroanatomical substrates mediating the disruptive effects of cannabinoids on memory. Intrahippocampal injections of CP-55,940 impaired maze performance in a dose-dependent manner (ED50=8 µg/rat), but did not retard the amount of time required to complete the maze. The effects of intrahippocampal CP-55,940 were apparently specific to cognition because no other cannabinoid pharmacological effects (e.g., antinociception, hypothermia, and catalepsy) were detected. This dissociation between choice accuracy in the radial-maze and other cannabinoid pharmacological effects suggests that the working memory deficits produced by cannabinoids may be mediated by cannabinoid receptors in the hippocampus.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Psychopharmacology 126 (1996), S. 125-131 
    ISSN: 1432-2072
    Keywords: Radial-arm maze ; Δ9-Tetrahydrocannabinol (Δ9-THC) ; Scopolamine ; Physostigmine ; SR141716A ; Cannabinoid antagonist ; Working memory
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The purpose of the present study was to investigate whether the cannabinoid and cholinergic systems impair working memory through a common mechanism. This hypothesis was tested by examining whether the cannabinoid antagonist SR141716A would ameliorate radial-arm performance deficits caused by either the naturally occurring cannabinoid, Δ9-THC, or scopolamine, a muscarinic antagonist. In addition, we evaluated whether the cholinesterase inhibitor, physostigmine, would prevent Δ9-THC-induced impairment of spatial memory. Finally, because the locomotor suppressive effects of cannabinoids may decrease radial arm choice accuracy independent of a direct effect on memory, we examined the impact of increasing the intertrial error on radial arm choice accuracy. As previously reported, Δ9-THC impaired maze performance (ED50=3.0 mg/kg). Increasing the intertrial interval from 5 s to 30 s resulted in a three-fold increase in the amount of time required to complete the maze without affecting choice accuracy. Importantly, SR141716A prevented Δ9-THC-induced deficits in radial-arm choice accuracy in a dose-dependent manner (AD50=2.4 mg/kg); however, the cannabinoid antagonist failed to improve the disruptive effects of scopolamine. Conversely, physostigmine failed to improve performance deficits produced by Δ9-THC. These data provide strong evidence that Δ9-THC impairs working memory through direct action at cannabinoid receptors. Moreover, these results suggest that scopolamine and Δ9-THC do not impair spatial memory in a common serial pathway, though they may converge on a third neurochemical system.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 160 (1975), S. 515-524 
    ISSN: 1432-0878
    Keywords: Ureteric innervation ; Mammals ; Interspecies differences ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The distribution and structure of the ureteric nerves in a small series of mammals was compared with that previously demonstrated in the rat. There was marked interspecies variation in the extent to which the nerves penetrated the wall of the ureter and in the degree of development of the deep submucous plexus. In animals with a highly developed deep submucous plexus, terminal arterioles frequently passed through the muscle coat before breaking up into capillaries. These vessels were surrounded by a fine periarteriolar plexus and were accompanied in their course through the muscle coat by one or more branches of the adventitial nerves. Intramuscular nerves not related to arterioles contained few axons with terminals classifiable as either adrenergic or cholinergic, and in animals in which the muscle cells were arranged in fascicles rather than in sheets, the nerves were typically interfascicular in position. As in the rat, only the periarteriolar plexuses contained large numbers of adrenergic axons. Cholinergic axons were generally few, but were not uncommon in the deep submucous plexus when this was well-developed. The majority of the terminals encountered in the intramural nerves contained variable and usually small numbers of both clear and large dense-cored vesicles. The relationship between these terminals and those defined in the submucous nerves of the rat ureter was discussed and it was suggested that the marked variations in the diameter of the axons in the terminal areas and in the number of vesicles in the terminals were related to the effects of the mechanical and other derangements which occur during processing.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 164 (1975), S. 133-144 
    ISSN: 1432-0878
    Keywords: Bladder body ; Mammals ; Musculature ; Innervation ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The distribution and structure of the nerves supplying the muscle of the body of the bladder in mammals such as the mouse, guinea-pig, rabbit, cat and dog was compared with that previously demonstrated in the rat. The muscle of the arterioles located between the muscle bundles is innervated by a fine perivascular plexus and the nerves forming the muscular plexus can be divided into inter-and intra-fascicular components. Terminals containing variable but usually small numbers of clear and large dense-cored vesicles are particularly numerous in the interfascicular nerves and the intrafascicular nerves are characterised by large numbers of terminals with the features of those of cholinergic axons. In addition to many small clear vesicles, the cholinergic terminals contained some small dense-cored vesicles, and it is suggested that, as in the rat, these contain a second transmitter which is released with acetylcholine at the terminals during impulse transmission. Adrenergic terminals are more common in the muscular plexuses of the guinea-pig, dog and cat than in those of the other animals studied and there is evidence for the presence of two types of such terminal in the nerves. Of these, one contains a much smaller proportion of small vesicles with dense cores and many more large dense-cored vesicles than the second, and the possibility of a relationship between such terminals and those of short adrenergic neurones and neurones associated with non-adrenergic patterns of impulse transmission is discussed.
    Type of Medium: Electronic Resource
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