Dynorphin- and enkephalin-like immunoreactivity is altered in limbic- basal ganglia regions of rat brain after repeated electroconvulsive shock

Abstract

In an attempt to determine whether the opioid peptides derived from prodynorphin participate in the effects of electroconvulsive shock (ECS), we used radioimmunoassay and immunocytochemistry to measure dynorphin-like immunoreactivity (DN-LI) in various rat brain regions after repeated ECS treatments. Ten daily ECSs caused a significant increase in dynorphin A (1-8)-LI in most limbic-basal ganglia structures, including hypothalamus (50%), striatum (30%), and septum (30%). No significant change was found in the frontal cortex or the neurointermediate lobe of the pituitary. In contrast, 10 ECS treatments depleted DN-LI in hippocampal mossy fibers by 64%. A detailed time-course study revealed that a single shock caused a small but significant increase in hippocampal DN-LI, whereas three consecutive shocks depleted DN-LI by 30%. The maximal decrease in DN-LI was reached after six daily ECSs. The level of DN-LI in the hippocampus partly recovered, but remained lower than the control value 4, 7, and 14 d after the cessation of six daily ECSs (50, 77, and 83% of control value, respectively). In contrast with the ECS-induced depletion of hippocampal dynorphin, 10 daily ECSs caused a significant increase (40%) in (Met5)-enkephalin-LI in the hippocampus, as well as in other limbic-basal ganglia structures. Immunocytochemistry revealed that enkephalin-LI was increased in the perforant pathway, which is presynaptic to the dynorphin-containing mossy fiber pathway in the hippocampus. These observations suggest that different mechanisms may regulate these two opioid peptide systems in the hippocampus.(ABSTRACT TRUNCATED AT 250 WORDS)

Seizures induce dramatic and distinctly different changes in enkephalin, dynorphin, and CCK immunoreactivities in mouse hippocampal mossy fibers

“…In contrast, the influence of seizures on dynorphin immunoreactivity has been less consistent; instances of increase (Iadarola et al, 1986;Kanamatsu et al, 1986b) and decrease (Iadarola et al, 1986;Kanamatsu et al, 1986a;McGinty et al, 1986) have both been reported.…”

“…The opioid peptides have been most extensively studied in this regard. Several treatments that induce recurrent or prolonged seizure activity, including repeated electroconvulsive shock (ECS) (Yoshikawa et al, 1985;Kanamatsu et al, 1986a), intracerebral kainic acid (Hong et al, 1980;Gall et al, 198 lb;McGinty et al, 1983;Kanamatsu et al, 1986b), and chemical and electrical kindling (Vindrola et al, 198 1, 1984;Iadarola et al, 1986;McGinty et al, 1986) have been found to elevate enkephalin levels in a number of brain areas, with some differences in the regional distribution of increased enkephalinlike immunoreactivity (ENK-I) between treatments. Work in this laboratory has demonstrated that recurrent seizure activity induced by small electrolytic lesions in the hilus of the dentate Figure 1.…”

Plasticity in Hippocampal Peptidergic Systems Induced by Repeated Electroconvulsive Shock

“…Changes in a variety of neuropeptides and peptide growth factors are associated with depression (Kubek et al 1985;Widerlöv et al 1986;Kanamatsu et al 1986;Stenfors et al 1989;Orzi et al 1990;Zetterstrom et al 1998;Mathe 1999;Pekary et al 1999Pekary et al , 2000. For example, depressed patients have decreased levels of cerebrospinal fluid neuropeptide Y (NPY) (Widerlöv et al 1986(Widerlöv et al , 1988Gjerris et al 1992).…”

Sustained Downregulation of YY1-Associated Protein-Related Protein Gene Expression in Rat Hippocampus Induced by Repeated Electroconvulsive Shock

“…ECS was performed as reported previously. 5) Briefly, ECS was administered via ear-clip electrodes (35 mA, 0.5 s) to induce a typical clonic-tonic seizure lasting 5-10 s. In acute experiments, the animals were decapitated 1, 3,6,12,24,48, and 72 h after a single ECS. In chronic experiments, ECS was administered every other day, totaling six shocks.…”