Prelimbic Cortical Injections of a GABA Agonist and Antagonist: In Vivo Quantification of the Effect in the Rat Brain Using [(18)F] FDG MicroPET.
OBJECTIVE
We evaluated the glucose metabolism after microinjections of a GABAA antagonist, bicuculline, and a GABAA agonist, muscimol, in the rat prelimbic cortex (PL) by small animal positron emission tomography (μPET).


METHODS
Following a microinjection of either 0.5 μl bicuculline (0.1 mg/ml), muscimol (1 mg/ml), or saline in the left PL of 11 healthy male Sprague Dawley rats (250-275 g), 2-deoxy-2-[(18)F]fluoro-β-D-glucose ([(18)F]FDG) PET images were acquired. Volume-of-interest (VOI)-based analysis and voxel-based statistical parametric mapping were performed (n = 9).


RESULTS
VOI-based analysis revealed significantly different [(18)F]FDG uptake following bicuculline versus muscimol in PL (p < 0.001), infralimbic cortex (p < 0.01), and cingulate cortex (p < 0.01). Voxel-based analysis showed bicuculline induced widespread significant hypermetabolism throughout the brain while muscimol induced significant localized hypometabolism.


CONCLUSIONS
Here, we visualize functional GABAA-mediated correlations of the PL following pharmacological stimulation. This could serve as a reference and shed light on the working and focality of other stimulation paradigms targeting this region.
Molecular Imaging Center Antwerp (MICA), University of Antwerp, Universiteitsplein 1, 2610, Wilrijk, Antwerp, Belgium.
Joke
J
Parthoens
Molecular Imaging Center Antwerp (MICA), University of Antwerp, Universiteitsplein 1, 2610, Wilrijk, Antwerp, Belgium. stijn.servaes@uantwerpen.be.
Stijn
S
Servaes
Molecular Imaging Center Antwerp (MICA), University of Antwerp, Universiteitsplein 1, 2610, Wilrijk, Antwerp, Belgium.
Jeroen
J
Verhaeghe
Molecular Imaging Center Antwerp (MICA), University of Antwerp, Universiteitsplein 1, 2610, Wilrijk, Antwerp, Belgium.|Department of Nuclear Medicine, University Hospital Antwerp, Wilrijkstraat 10, 2650, Edegem, Antwerp, Belgium.
Sigrid
S
Stroobants
Molecular Imaging Center Antwerp (MICA), University of Antwerp, Universiteitsplein 1, 2610, Wilrijk, Antwerp, Belgium. steven.staelens@uantwerpen.be.
Steven
S
Staelens
D000818:Animals; D019788:Fluorodeoxyglucose F18 / Q000008:administration & dosage*; D018755:GABA Agonists / Q000008:administration & dosage*; D018756:GABA Antagonists / Q000008:administration & dosage*; D008032:Limbic System / Q000000981:diagnostic imaging*; D008297:Male; D049268:Positron-Emission Tomography / Q000379:methods*; D051381:Rats; D017207:Rats, Sprague-Dawley
D018755:GABA Agonists; D018756:GABA Antagonists; D019788:Fluorodeoxyglucose F18
Bicuculline; Medial prefrontal cortex; Muscimol; Prelimbic cortex; [18F]FDG; microPET