BRAIN RESEARCH ELSEVIER Brain Research 698 (1995) 39-45 Research report Concurrent analysis of neuropeptides and biogenic amines in brain tissue of rats treated with electroconvulsive stimuli Carina Stenfors a, ,, Per Bjellerup a, Aleksander A. Math6 b, Elvar Theodorsson a Karolinska Institute, Departments of Laboratory Medicine, Karolinska Hospital, Stockholm, Sweden b Clinical Neuroscience, St Ggran's Hospital, Stockholm, Sweden Accepted 13 June 1995 Abstract We developed a method for measuring neuropeptides and monoamines in the same rat brain tissue and applied this method to study the effects of electroconvulsive stimuli (ECS) on these compounds. Rats were treated with repeated ECS or sham ECS. After sacrifice by focused microwave irradiation, brains were dissected and immediately frozen. The tissues were extracted in acetic acid. After lyophilization the samples were reconstituted in phosphate buffer and divided in three fractions: (1) was further purified on a cation-exchange column before catecholamines were measured on a high-performance liquid chromatography (HPLC) system, (2) for measuring serotonin on the HPLC system, (3) for measuring peptide concentrations by specific radioimmunoassays. Confirming our previous findings, ECS significantly increased neuropeptide Y-like immunoreactivity (-LI) in hippocampus and frontal cortex and neurokinin A-LI in the hippocampus, while no changes in substance P- and neurotensin-LI were detected. New findings were a decrease in noradrenaline concentrations in the frontal and occipital cortex and hippocampus, an increase in dopamine concentrations in the frontal and occipital cortex and no serotonin change. In summary, we have developed methods to measure both peptides and monoamines in the same brain tissue specimens, and have shown that ECS leads to changes in both neuropeptides and classical neurotransmitters in distinct brain regions. K£vwords: Brain (rat): Dopamine; Electroconvulsive stimulus (ECS); Neuropeptide; Noradrenaline; Serotonin 1. Introduction Recently we demonstrated that a series of grand mal seizures, elicited by repeated electroconvulsive stimuli (ECS) [27,28,31] or chemically [29], had a marked effect on neuropeptide Y (NPY)- and neurokinin A (NKA)-LI in discrete rat brain regions. On the basis of these results we hypothesized that the increase in peptide concentrations lbllowing grand real seizures could constitute one of ECT's therapeutic modes of action. In view of the co-localization of neuropeptides with the neurotransmitters that are presumed to be of relevance in depression [e.g., NKA and substance P (SP) with 5-HT; NPY with NA and neurotensin (NT) with DA] [5,9,16-18] and influenced by antidepressive treatments we deemed it relevant to study the effect of repeated ECS on monoamines * Corresponding author. Department of Clinical Chemistry, Karolinska Hospital, S-t71 76 Stockholm, Sweden. Fax: (46) (8) 729-4944. 0006-8993/95/$09.50 © 1995 Elsevier Science B.V. All rights reserved SSDI 0006-8993( 05 )00784-9 and neuropeptides in the same rat brain tissue specimens and developed a method for this purpose. 2. Materials and methods 2.1. Animals and test procedure Twenty male Sprague Dawley rats (ALAB, Sollentuna, Sweden) weighing 200-220 g at the beginning of the experiment, were used. They were housed six to a cage at constant room temperature (21 _+ I°C) with free access to water and standard rat food and with 12 h light/dark cycle. The rats were treated either with six transauricular ECS (150 V, 50 Hz, 20 ms stimuli for l s), given three times a week to unanesthesized animals, using a Grass S-44 stimulator, or with six sham ECS (no current passed). Fifteen rain following the last ECS/sham ECS the rats were sacrificed by focused microwave irradiation [22,36], brains were dissected according to the method of Glowin- ski and Iversen [12] and immediately frozen on dry ice.