Insulin-dependence of pain pressure threshold in STZ-normoglycemic rats. Two weeks after injection of STZ pain pressure threshold of STZ-NG rats is decreased in proportion to the plasma insulin level (R = 0.97; A). Insulin replacement initiated one week after STZ injection (horizontal bar in panel B) does not change PPT of control or hyperglycemic rats, but corrects it in STZ-normoglycemic animals (empty and filled circles, and filled triangles, respectively). Insulin replacement, does not affect blood glucose (C), but normalizes plasma insulin level (D) in STZ-NG rats. In C and D white, grey and black columns represent control, STZ-NG and STZ-HG rats, respectively.