Acute and chronic electroconvulsive shock in rats: effects on peripheral markers of neuronal injury and glial activity.

Electroconvulsive therapy is considered one of the most effective treatments of major depression, but controversy still exists on whether it may be brain damaging. The aim of this work was to evaluate the cerebrospinal fluid (CSF) levels of neuron specific enolase (NSE), protein S100B and lactate of rats submitted to acute and chronic models of ECS. Rats were submitted to either one shock (acute) or a series of eight shocks, applied one at every 48 h (chronic). CSF samples were collected at 0, 3, 6, 12, 24, 48 and 72 h after the shock in the acute model and at these same time intervals after the last shock in the chronic model. Both models did not produce significant alterations in the levels of NSE. S100B levels were significantly increased at 6 h in the chronic model (p<0.0001). There was a significant increase in the levels of lactate at 0 h in both models (p<0.001). These results support the proposition that ECS does not produce neural damage, and suggest that the alterations in the levels of S100B and lactate may reflect an astrocytic activity of a protective nature.

Guanine and adenine nucleotidase activities in rat cerebrospinal fluid.

Adenine and guanine nucleotides have been shown to exert multiple roles in central and peripheral nervous systems, and the sequential breakdown of these nucleotides by enzymatic systems is an important step in the modulation of their extracellular effects. The aim of this study was to investigate whether nucleotide hydrolysis also occurs in the cerebrospinal fluid (CSF) of rats. CSF was able to hydrolyze all guanine and adenine nucleotides investigated (2.0 mM): GDPz.Gt;ADP=ATP=GTPz.Gt;AMP=GMP. More detailed studies with the diphosphate nucleotides showed that the hydrolysis of ADP and GDP was linear with incubation time and protein concentration. The apparent K(M) (Henry-Michaelis-Menten constant) and V (maximal velocity) values for ADP and GDP were 164.3+/-54.7 microM and 12.2+/-3.8 nmol P(i)/min per mg protein, and 841.0+/-90.2 microM and 22.8+/-8.0 nmol P(i)/min per mg protein. The sum of ADP, GDP and UDP hydrolysis (2.0 mM) upon individual incubations with CSF was similar to the hydrolysis observed when all three nucleotides were incubated together. This pattern of hydrolysis strongly suggests the involvement of more than one enzyme activity. The higher maximum activity for GDP and UDP compared to ADP is compatible with presence of a soluble NTDPase5.