The effects of metabolic stress and vagotomy on emotional learning in an animal model of anxiety.
The aim of the present study is to evaluate the role of the blood glucose (BG) level in emotional learning in the elevated plus maze (EPM), an animal model of anxiety. In Experiment 1, male Wistar rats were submitted to different EPM trial lengths (1- or 5-min). Blood samples were withdrawn before and after the maze exploration, through a polyethylene cannula chronically implanted into the jugular vein. In Experiment 2, the animals received either saline or 2-deoxy-D-glucose, a glucoprivic drug (2-DG, 250 or 500 mg kg(-1)) by i.p. route, 30 min before a 5-min EPM exposure and were retested in the maze (Trial1/Trial2 EPM procedure) 24 h later. In an independent group of rats, blood samples were withdrawn 0, 5, 15, and 30 min after 2-DG administration, through the jugular vein, to determine BG. In Experiment 3, the animals underwent a vagotomy and were tested in a Trial1/Trial2 EPM procedure four weeks later. The results showed that rats exploring the EPM for 5 min displayed increased fear and higher hyperglycemia than those exploring the EPM for 1 min. In addition, rats submitted to 5-min EPM Trial1 length displayed higher level of fear on Trial2, as well as higher percentage of shortening of the %Open arm entries and %Open arm time from Trial1 to Trial2, which characterizes the occurrence of emotional learning. In contrast, rats previously vagotomized or treated with 2-DG (500 mg kg(-1)) showed the same level of fear on both EPM trials and a low percentage of shortening, from Trial1 to Trial2, of the %Open arm entries and %Open arm time, indicating poor emotional learning. The data is discussed regarding the role of glycaemia in emotional learning in the EPM.
Ghizoni
Daniel Matias
DM
Department of Physiological Sciences, Centre of Biological Sciences, Federal University of Santa Catarina, 88.040-900, Florianópolis, SC, Brazil.
João
Liziane Moro
LM
Moratelli Neto
Leopoldo
L
da Cunha
Isabel Cristina
IC
Orlandi Pereira
Lenir
L
Borges
Fábio Rodrigo Mesquita
FR
Battisti
Rúbia
R
de Oliveira
Luisa Guedes
LG
Meneghini
Luana
L
Lucinda
Aparecida Márcia
AM
Marino Neto
José
J
Paschoalini
Marta Aparecida
MA
Faria
Moacir Serralvo
MS
D000704:Analysis of Variance; D000818:Animals; D001007:Anxiety / Q000097:blood* / Q000150:complications; D001245:Association Learning / Q000502:physiology*; D001786:Blood Glucose / Q000378:metabolism*; D004195:Disease Models, Animal; D004644:Emotions / Q000502:physiology; D004734:Energy Metabolism / Q000502:physiology; D005106:Exploratory Behavior / Q000502:physiology*; D006943:Hyperglycemia / Q000097:blood* / Q000209:etiology; D008297:Male; D018782:Maze Learning / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D013315:Stress, Psychological / Q000097:blood* / Q000150:complications; D014628:Vagotomy
D001786:Blood Glucose