Fig. 7.

Antecedent insulin-induced hypoglycemia reduces activation of adrenergic neurons in medullary C1 and C3 nuclei after subsequent hypoglycemia: neuronal activation represented by double-stained Fos+ phenylethanolamine-N-methyltransferase (PNMT)+ neurons expressed as % of total PNMT+ neurons in the C1 (A) and C3 (B) regions (n = 4 animals/group). The ratio of activated catecholaminergic neurons in both regions was significantly higher in the single-hypoglycemia (hypo) group compared with the repeated-hypo group. There was no recovery in C1 or C3 neuronal activation after hypo prevention or naloxone treatment. Data are means ± SE. Statistical significance was determined by 1-way ANOVA and multiple-comparison analysis with a Holm-Šidák correction. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001, significantly different from all other groups.