Blockade of GABAA Receptors in the Ventromedial Hypothalamus Further Stimulates Glucagon and Sympathoadrenal but Not the Hypothalamo-Pituitary-Adrenal Response to Hypoglycemia
Article Figures & Tables
Figures
- FIG. 1.
Representative picture of a coronal rat brain section depicting the typical position of microinjection probes. In the left panel, the ball indicates the end of the guide cannula and the small bar indicates the 1-mm extension of the microinjection needle.
- FIG. 2.
Plasma glucose concentrations of rats receiving the artificial ECF vehicle (control; n = 8), the GABA antagonist bicuculline methiodide (n = 8), and the GABA agonist muscimol (n = 10) during the hyperinsulinemic-hypoglycemic glucose clamp.
- FIG. 3.
Average plasma insulin concentrations (A) and glucose infusion rates (B) during the final 90 minutes of the hypoglycemic clamp for rats receiving the artificial ECF vehicle (control; n = 8), the GABA antagonist bicuculline methiodide (n = 8), and the GABA agonist muscimol (n = 10). Results are presented as means ± SE. *P < 0.05 vs. controls.
- FIG. 4.
Plasma glucose responses during the hypoglycemic clamp for rats receiving the artificial ECF vehicle (control; n = 8), the GABA antagonist bicuculline methiodide (n = 8), or the GABA agonist muscimol (n = 10). Results are presented as means ± SE. *P < 0.04 vs. controls; †P < 0.05 vs. controls.
- FIG. 5.
Epinephrine (A) and norepinephrine (B) responses during the hypoglycemic clamp for rats receiving the artificial ECF vehicle (control; n = 8), the GABA antagonist bicuculline methiodide (n = 8), and the GABA agonist muscimol (n = 10). Results are presented as means ± SE. *P < 0.001 vs. controls; †P < 0.05 vs. controls.
- FIG. 6.
Plasma cortisone concentrations during the hypoglycemic clamp for rats receiving the artificial ECF vehicle (control; n = 8), the GABA antagonist bicuculline methiodide (n = 8), or the GABA agonist muscimol (n = 10). Results are presented as means ± SE.
- FIG. 7.
Plasma glucose concentrations of rats receiving the artificial ECF vehicle (control; n = 5) and the GABA agonist muscimol (n = 6) during the hyperinsulinemic-euglycemic glucose clamp.
- FIG. 8.
Plasma glucagon responses during the euglycemic clamp for rats receiving the artificial ECF vehicle (control; n = 5) and the GABA agonist muscimol (n = 6). Results are presented as means ± SE.
- FIG. 9.
Epinephrine (A) and norepinephrine (B) responses during the euglycemic clamp for rats receiving the artificial ECF vehicle (control; n = 5) and the GABA agonist muscimol (n = 6). Results are presented as means ± SE.
- FIG. 10.
Plasma corticosterone concentrations during the hypoglycemic clamp for rats receiving the artificial ECF vehicle (control; n = 5) and the GABA agonist muscimol (n = 6). Results are presented as means ± SE.
Tables
- TABLE 1
Baseline hormone concentrations for the hypoglycemic clamp study
Control Bicuculline Muscimol n 8 8 10 Body weight (g) 334 ± 7 330 ± 8 334 ± 14 Plasma glucose (mmol/l) 6.3 ± 0.1 6.1 ± 0.2 6.2 ± 0.2 Corticosterone (ng/ml) 63 ± 14 89 ± 23 67 ± 30 Glucagon (ng/l) 39 ± 5 37 ± 2 44 ± 5 Epinephrine (pg/ml) 87 ± 27 95 ± 35 51 ± 14 Norepinephrine (pg/ml) 87 ± 32 112 ± 18 121 ± 14 Insulin (μU/ml) 11 ± 5 18 ± 10 10 ± 2 Data are means ± SE.
- TABLE 2
Baseline hormone concentrations for the euglycemic clamp study
Control Muscimol n 5 6 Body weight (g) 338 ± 7 314 ± 1 Plasma glucose (mmol/l) 5.8 ± 0.2 5.9 ± 0.5 Corticosterone (ng/ml) 29 ± 3 44 ± 6 Glucagon (ng/l) 38 ± 5 41 ± 12 Epinephrine (pg/ml) 52 ± 1 61 ± 24 Norepinephrine (pg/ml) 75 ± 16 80 ± 19 Insulin (μU/ml) 28 ± 9 10 ± 4 Data are means ± SE.
In this Issue
