Electrolytic lesions

Surgical or electrolytic lesions of a particular pathway or nucleus. Even with precise location and subsequent histological verification this approach rarely ablates all the axons (or neurons) in a pathway using the NT under study and can also affect other... 

While the nigrostriatal pathways are ipsilateral some crossing occurs in fibres from the ventral tegmental AlO nucleus. These pathways are shown diagramatically in Fig. 7.1. Further details can be obtained from Moore and Bloom (1978) and Lindvall and Bjorkland (1978). The nuclei provide distinct loci for activating the dopamine systems for electrophysiological, release and behavioural studies and for their destruction by electrolytic lesion or injection of the toxin 6-hydroxydopamine (6-OHDA). 

There appear to be important exceptions to the rule that a decrease in the availability of 5-HT in the mesolimbic pathway leads to increases in locomotor and investigatory activity. In contrast to the dramatic and pervasive hyperactivity produced by electrolytic lesions of the median raphe, similar depletions of 5-HT following the neurotoxic dihydroxytryptamines produce relatively subtle effects that appear to be related to the environmental context in which the behavior is monitored. For instance, microinjections of 5,7-DHT into the median raphe had no effect on the level of activity in a novel environment, whereas the same animals were hyperactive in a familiar environment (54). 

Gewirtz JC, Falls WA, Davis M (1997) Normal conditioned inhibition and extinction of freezing and fear-potentiated startle following electrolytic lesions of medical prefrontal cortex in rats. Behav Neurosci 111 712-726... 

Koegler-Muly SM, Owens MJ, Ervin GN, Kilts CD, Nemeroff CB (1993) Potential corticotropin-releasing factor pathways in the rat brain as determined by bilateral electrolytic lesions of the central amygdaloid nucleus and paraventricular nucleus of the hypothalamus. J Neuroendocrinol 5 95-98... 

D. Bochelen, F. Eclancher, A. Kupferberg, A. Privat and M. Mersel, 7(5-hydroxycholesterol and 7p-hydroxycholesteryl-3-esters reduce the extent of reactive gliosis caused by an electrolytic lesion in rat brain, Neuroscience 51 (1992) 827-834. 

Ji, J., and Maren, S. (2005). Electrolytic lesions of the dorsal hippocampus disrupt renewal of conditional fear after extinction. Learn. Mem. 12, 270—276. 

Costall B, Marsden CD, Naylor RJ, Pycock CJ (1976) The relationship between striatal and mesolimbic dopamine dysfunction and the nature of circling responses following 6-hydroxydopamine and electrolytic lesions of the ascending dopamine systems of rat brain. Brain Res 773 87-113. 

Winn P, Tarbuck A, Dunnett SB (1984) Ibotenic acid lesions of the lateral hypothalamus comparison with the electrolytic lesion syndrome. Neuroscience 72 225-240. 

High concentration of extracellular potassium (50 mM), which results in cellular depolarization, decreases NGF production by 30% in explanted rat iris (Hellweg et al., 1988). In contrast, elevated potassium levels increase the concentration of rjjRNANGF jjj cultured hippocampal neurons (2 fra et al., 1990). Depolarization produced by electrolytic lesions or systemic intraventricular administration of glutamate receptor agonists produces a rapid rise in mRNA p in vivo (Gall and Isackson, 1989 Zafra et al., 1990 Gall et al., 1991). 

This was shown in studies using focal electrolytic lesions of the dentate gyrus, which induced 10 h of intermittent limbic seizures (Gall and Isackson,... 

In contrast to the upregulation of NGF and BDNF, a transient decrease of NT-3 mRNA was found after an electrolytic lesion of the hilus (Rocamora et al., 1992) and also following cerebral ischemia and hypoglycemic coma (Lindvall et al., 1992 Takeda et al. 1992, 1993 Kokaia et al.,... 

Electrolytic lesions to the nucleus raph dorsalis cause a marked decrease in forebrain 5-HT levels which results in an antagonism of morphine analgesia [272,273], but not of methadone or pethidine analgesia [274]. This led the authors to suggest that morphine may be atypical (amongst opiate analgesics) in its reliance upon intact 5-HT pathways. There have been other reports that methadone [146] and pethidine [258,259] behave differently from morphine, as they do not increase rat brain 5-HT turnover following their acute administra-... 

Stress or psycho-social factors have often been described as conducive to atherosclerosis disease. This approach to the causation of myocardial in jury is discussed in a provocative article by Roab . It is also interesting to note that Friedman and coworkers were able to induce hj per-cholesteremia in the rat neurogenically by an electrolytic lesion in the brain. 

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