FUNCTIONAL AND BIOCHEMICAL CHANGES IN BRAIN TISSUES AND CEREBROSPINAL FLUID DURING INDUCED CONVULSIONS OF SHEEP

Certain functional and biochemical changes that occur in the parenchyma of the brain and spinal cord are reflected in the cerebrospinal fluid (CSF) . Although CSF was known to have a mechanical function of protecting the brain and spinal cord from traumatic injuries, it was not given physiologic significance until the concept of a “blood brain barrier” came into being after the turn of the 20th century. Elevation in CSF enzyme activities such as transaminases (glutamic-oxalacetic (GOT) and glutamic-pyruvic (GPT), and lactic dehydrogenase ( L D H ) has been reported to be associated with several neuropathological conditions in humans, dogs, and cats (Fleisher & Wakim, 1956; Fleisher et al., 1957; Lieberman et al., 1957; Lending et al., 1959 & 1961 ). Under normal conditions, these enzymes are contained almost entirely within the tissue cells, although limited activities are normally found in the blood serum and CSF. It is generally believed that cellular degeneration results in the release of these enzymes into the tissue fluid and eventually into the blood and CSF. Some reports in the literature indicate that elevations in G O T and LDH activities of CSF are associated with nonspecific fulminating central nervous system (CNS) damage, such as cerebrovascular accidents, and with diverse conditions including thrombo-embolisms, infections, degeneration, and some neoplastic conditions (Green et al., 1957a, 1957b & 1959). Many reports have appeared concerning CSF enzyme activities associated with neuropathological conditions in humans and small animals, although there are few such reports pertaining to livestock. Because of species variation, the findings in humans and small animals may not necessarily be applicable to livestock. For instance, Cornelius rr al. ( 1959) and Buck et al. ( 1961) have reported that sheep and cattle do not have significant elevations in blood serum glutamic pyruvic transaminase (SGPT) activities following acute liver necrosis, as d o dogs and humans. The cationic composition of the CNS and CSF has been studied extensively ( Leusen. 1950; Davson, 1956; Woodbury & Karler, 1960). These reports showed that the CSF content of K + , N a + , C a t +, and Mg+ + has a definite effect upon brain excitability. Although considerable research has been directed toward determining the effect of alterations in CSF electrolytes on C N S activity, less emphasis has been given to the study of effects of brain activity on CSF electrolyte composition. There is little information in the literature pertaining to the electrolyte composition of CSF taken serially before, during, and following convulsive seizures. There are apparently no reports in the literature on the use of permanently implanted catheters in the CSF space for measuring changes in the CSF during