Distribution of GABA in the periaqueductal gray matter. Effects of medial hypothalamic lesions.
Gas chromatography and chemical ionization mass spectrometry were used in order to measure the GABA (gamma-aminobutyric acid) concentration in a series of successive horizontal slices of the mesencephalic periaqueductal gray (CG) as well as in a series of successive frontal CG slices in the rat. Along the dorso-ventral axis, the GABA concentration (3.5-7 microgram/mg protein) was found first to increase and then to decrease, a maximum concentration being found at the level of the aqueduct. In contrast, no concentration gradient was found along the caudo-rostral axis. In an additional experiment, the medial hypothalamus (MH) was lesioned on one side and the effect of such a unilateral MH lesion on the caudo-rostral distribution of GABA was investigated. Fifteen days after performing the lesion, a graded decrease in GABA concentration--with a maximum in the rostral CG--was found to occur mainly on the lesioned side.
D000818:Animals; D001921:Brain / Q000378:metabolism*; D008401:Gas Chromatography-Mass Spectrometry; D007031:Hypothalamus / Q000502:physiology*; D007700:Kinetics; D008297:Male; D008636:Mesencephalon / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
D005680:gamma-Aminobutyric Acid