Effect of repeated electroconvulsive treatment on regional concentrations of tachykinins, neurotensin, vasoactive intestinal polypeptide, neuropeptide Y, and galanin in rat brain

Abstract

The effects of single and repeated electroconvulsive treatments (ECTs) on brain regional distribution of substance P (SP), neurokinin A (NKA), neurotensin (NT), neuropeptide Y (NPY), vasoactive intestinal polypeptide (VIP), and galanin (GAL) were studied in the rat. Rats were divided into four groups receiving one of the following treatments: one ECT, one sham ECT, six ECTs, or six sham ECTs. After sacrifice by focused microwave irradiation, brains were dissected into frontal cortex, striatum, occipital cortex, hippocampus, hypothalamus, and pituitary sections. Peptides were extracted by boiling the tissues in 1 mol/l acetic acid and measured in extract aliquots by specific radioimmunoassays. Marked regional differences (P =.0005) were found for each of the peptides measured. The highest concentrations of SP and NKA were found in the hypothalamus and, in descending order, in striatum, pituitary, frontal cortex, occipital cortex, and hippocampus. For NT, the highest level was found in the hypothalamus and, in descending order, in pituitary, striatum, hippocampus, frontal cortex, and occipital cortex. The highest VIP concentrations were measured in frontal and occipital cortex, followed by pituitary, hypothalamus, striatum, and hippocampus. The highest NPY and GAL concentrations were found in the hypothalamus and the pituitary; in frontal and occipital cortex, as well as in the striatum and hippocampus, the peptides levels were rather evenly distributed. Repeated handling (stress?) decreased both NT and GAL in frontal (P =.05 and.04) and occipital cortex (P =.09 and.07). ECT, one or six treatments, had no effect on SP, NKA, NT, VIP, or GAL concentrations in different brain regions. However, an increase in NPY concentrations in hippocampus (six sham ECTs vs. six ECTs = right: 112 ± 61 vs. 246 ± 159, and left: 143 ± 42 vs. 303 ± 160 pmol/g; P =.0005) and occipital cortex (right: 118 ± 42 vs. 167 ± 98; and left: 97 ± 45 vs. 157 ± 42 pmol/g, P =.003) was obtained after six ECTs but not following a single treatment. The results demonstrate a regional effect of ECT on NPY and raise the possibility that one of the ECTs' modes of action may be by elevating NPY levels in the CNS.