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The influence of sex on extracellular dopamine and locomotor activity in C57BL/6J mice before and after acute cocaine challenge
Author(s) -
Griffin W.C.,
Middaugh L.D.
Publication year - 2006
Publication title -
synapse
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.809
H-Index - 106
eISSN - 1098-2396
pISSN - 0887-4476
DOI - 10.1002/syn.20218
Subject(s) - microdialysis , saline , striatum , locomotor activity , extracellular , dopamine , conditioning , psychology , pharmacology , anesthesia , drugs of abuse , endocrinology , medicine , addiction , neuroscience , chemistry , statistics , mathematics , biochemistry
C57BL6/J (C57) mice serve as a useful animal model of cocaine abuse because they self‐administer cocaine, exhibit place conditioning to cocaine, discriminate the interoceptive cues of cocaine, and are used for backcrossing strains of genetically modified mice. The present study was to examine the influence of sex on extracellular DA and locomotor activity in C57 mice in response to acute cocaine challenge. In the first experiment, male and female mice were implanted with guide cannulae aimed at the dorsal striatum. Microdialysates were collected in three consecutive phases: baseline, post‐saline injection, and post‐cocaine injection. Sex did not influence DA measurements during baseline or after intraperitoneal (i.p.) saline injection. Cocaine (20 mg/kg) injections increased peak extracellular DA of both sexes, and the increase was greater for males (278% ± 14.0%) than females (182.5% ± 10.8%) ( P < 0.05). In the second experiment, under conditions similar to the microdialysis experiment, locomotor activity of male and female mice was assessed during baseline, after saline injection, and after cocaine injection (5, 10, 20, or 40 mg/kg). Cocaine dose‐dependently increased activity; however, sex did not influence locomotor activity during baseline, after saline, or after any cocaine dose. Results of the experiments established that cocaine (20 mg/kg) increased extracellular DA in the dorsal striatum to a greater extent in male than in female mice; however, when cocaine was administered under similar experimental conditions, sex did not influence cocaine stimulation of locomotor activity over a wide range of doses. Synapse 59:74–81, 2006. © 2005 Wiley‐Liss, Inc.