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                                          Chronobiology International
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Serotonin and blood flow

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Summary
Chronobiology International
1993, Vol. 10, No. 6, Pages 442-448
Effects of Intracisternally Injected Serotonin on Cerebral Blood Flow in Cats During Winter and Summer, and After Dark Exposure

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Transcript of "Serotonin and blood flow"

  1. 1. Summary Chronobiology International 1993, Vol. 10, No. 6, Pages 442-448 Effects of Intracisternally Injected Serotonin on Cerebral Blood Flow in Cats During Winter and Summer, and After Dark Exposure 1† 1 1 1 2 Phillip E. Vinall , John J. Michele , David A. Gordon , Christopher Deitch and Frederick A. Simeone 1 Department of Nenrosurgery, Pennsylvania Hospital, Philadelphia, Pennsylvania 2 Division of Neurosurgery, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA † Correspondence: Phillip E. Vinall, Neuroscience Research Institute, Pennsylvania Hospital, 800 Spruce Street, Philadelphia, PA, 19107, USA This investigation reports on two experiments: (a) The examination of the effects of intracisternally injected serotonin on cerebral blood flow and systemic pressure in cats during winter (1/10–3/7) and summer (7/6–9/3) at a latitude of 39' 40, and (b) the effects of similarly injected serotonin on the same parameters in 11 cats after exposure to 3 days of continuous darkness during the summer months. Serotonin (5 mg) injected intracisternally produced significant decreases in cerebral blood flow and systemic pressure that lasted from 60 to 180 min after injection. Blood flow decreases, expressed as percentage change from baseline, seen during winter (n = 24) periods were significantly greater [analysis of variance (ANOVA), p < 0.02] from decreases seen during summer (n = 25) periods. Following serotonin injection, systemic pressure decreases between the winter and summer cats were not significantly different. Eleven summer cats were subjected to 3 days of continuous darkness before being injected with serotonin. Blood flow decreases in the dark-exposed cats were significantly (p < 0.05) greater than those seen in normal light-exposed cats, whereas systemic pressure changes were not different. These studies suggest that the seasonal photoperiod may affect the sensitivity of cerebral vessels to intracisternally injected serotonin in cats.

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