Ketamine Anesthesia (ketamine + anesthesia)

Distribution by Scientific Domains

Selected Abstracts

Kindling Limits the Interictal Neuronal Temporal Response Properties in Cat Primary Auditory Cortex

EPILEPSIA, Issue 2 2005
Pamela A. Valentine
Summary:,Purpose: The present study examined the effect of electrical kindling on the interictal temporal response properties of single units recorded from primary auditory cortex (AI) of the adult cat. Methods: Cats were permanently implanted with electrodes in AI, kindled twice daily for 40 sessions, and the contralateral AI was subsequently mapped. Kindling stimulation consisted of 1-s trains of biphasic square-wave pulses applied at a frequency of 60 Hz, 100 ,A above the afterdischarge (AD) threshold. The EEG activity was recorded during each kindling session, and the behavioral manifestation was scored. Subsequent to kindling, multiple single-unit responses were recorded under ketamine anesthesia in response to 1-s-long periodic click trains, with click rates between 2 and 64 Hz. Neuronal responses were characterized according to their ability to respond in time-locked fashion to the clicks. Results: Kindling stimulation resulted in progression of the AD characteristics and seizure behavior, with six of 10 kindled cats reaching a fully generalized state. In the fully kindled cats, the best modulation frequencies and limiting following rates for the single-unit responses were significantly lower compared with those of naive and sham controls. Conclusions: Repeated epileptiform activity interferes with temporal processing in cat auditory cortex in the interictal state. This may have implications for people with epileptic foci in auditory-related areas. [source]

Dose-dependent effect of S(+) ketamine on post-ischemic endogenous neurogenesis in rats

Background: Ketamine is a non-competitive antagonist at N -methyl- d -aspartate (NMDA) receptors and reduces neuronal injury after cerebral ischemia by blocking the excitotoxic effects of glutamate. However, cerebral regeneration by means of endogenous neurogenesis may be impaired with blockade of NMDA receptors. The effects of S(+) ketamine on post-ischemic neurogenesis are unknown and investigated in this study. Methods: Thirty-two male Sprague,Dawley rats were randomly assigned to the following treatment groups with intravenous S(+) ketamine anesthesia: S(+) ketamine 0.75 mg/kg/min with or without cerebral ischemia and S(+) ketamine 1.0 mg/kg/min with or without cerebral ischemia. Eight non-anesthetized, non-ischemic animals were investigated as na´ve controls. Forebrain ischemia was induced by bilateral common carotid artery occlusion in combination with hemorrhagic hypotension. 5-bromo-2-deoxyuridine (BrdU) was injected intraperitoneally for seven consecutive post-operative days. BrdU-positive neurons in the dentate gyrus and histopathological damage of the hippocampus were analyzed after 28 days. Results: The number of new neurons was not affected by S(+) ketamine in the absence of cerebral ischemia. The ischemia-induced increase in neurogenesis was reduced by high-dose S(+) ketamine. Cell death of ischemic animals did not vary between low- and high-dose S(+) ketamine. Conclusion: While low concentrations of S(+) ketamine allow an ischemia-induced increase in the number of new neurons, high S(+) ketamine concentrations block the post-ischemic increase in newly generated neurons. This effect is irrespective of the extent of other histopathological damage and in line with studies showing that NMDA receptor antagonists like MK-801 inhibit neurogenesis after cerebral ischemia. [source]

Effect of ketamine anesthesia on daily food intake in Macaca mulatta and Cercopithecus aethiops,

Danielle A. Springer
Abstract Ketamine hydrochloride is frequently administered to non-human primates as a means of chemical restraint. This procedure can be a frequent source of stress to monkeys at research facilities, impacting animal health, well-being and research quality. This study was designed to measure ketamine's effect on daily food intake, a parameter that reflects and influences animal well-being and directly impacts research studies. On five occasions, baseline daily food intake was compared to daily food intake occurring 24, 48, 72, 96, and 120,h after an intramuscular injection of 10,mg/kg ketamine in male African green monkeys (AGMs) (Cercopithecus aethiops) and male and female rhesus macaques (Macaca mulatta). AGMs and female rhesus macaques had significantly reduced daily food intake during the first 4 days after receiving ketamine. The AGMs continued to display significantly reduced daily food intake on the fifth day after ketamine. The male rhesus macagues showed a trend toward reduced daily food intake, greatest during the first 2 days and remaining less than baseline intake through the fifth day following ketamine. The degree of observed food intake reduction was most severe at the 24,h (mean percent intake reduction: AGMs: 57%; rhesus males: 48%; rhesus females: 40%) and 48,h time points (AGMs: 24%; rhesus males: 14%; rhesus females: 13%). A subset of the AGMs that did not receive ketamine, but observed other animals in the room receive ketamine, showed reduced food intake at 24 and 48,h after ketamine, though not to the degree associated with ketamine administration. These results indicate that ketamine anesthesia is associated with a prolonged reduction in daily food intake in AGMs and rhesus macaques. Frequent use of ketamine in non-human primates may have a significant impact on animal health and well-being, and alternatives to its use warrant consideration. Am. J. Primatol. 69:1080,1092, 2007. Published 2007 Wiley-Liss, Inc. [source]