Effects of repetitive hypoglycemia on neuroendocrine response and brain tyrosine hydroxylase activity in the rat

Hypoglycemia-associated autonomic failure (HAAF) is a syndrome of acute adaptation to a metabolic stressor, in which neuroendocrine responses to repetitive hypoglycemic bouts are blunted. The CNS mechanisms that contribute to HAAF are unknown. In the present study, we modeled HAAF in the rat and measured the activity of tyrosine hydroxylase (TH) as an index of acute noradrenergic activation, to test the hypothesis that noradrenergic activation of the hypothalamus might be impaired. In association with a significant counter-regulatory response to a single bout of hypoglycemia (elevated corticosterone, catecholamines, and glucagon), TH activity was elevated overall in brainstem NE cell body areas and hypothalamus. With multiple hypoglycemic episodes in a 24 h period, the counter-regulatory response was blunted, and hypothalamic TH activity was comparable to that of saline-infused controls. In a similar paradigm, multiple bouts of CNS neuroglucopenia did not blunt the hyperglycemic or corticosterone responses, and were required for elevation of TH activity. This alternate response pattern suggests that insulin-induced hypoglycemia and cerebral neuroglucopenia represent somewhat different metabolic stressors at the CNS.     

Acquired Capability for Suicide,Pain Tolerance,and Fearlessness of Pain—Validation of the Pain Tolerance Scale of the German Capability for Suicide Questionnaire

The interpersonal theory of suicide (Joiner, 2005) postulates that for a serious suicide attempt, one has to possess the acquired capability to commit suicide. Acquired capability includes higher pain tolerance, which is further assumed to comprise both an elevated physical pain tolerance and fearlessness of pain. Recently, the German Capability for Suicide Questionnaire (GCSQ) was validated. The aim of this study is further validation of the GCSQ's Pain Tolerance scale by investigating the scale's association with objective pain tolerance and fearlessness of pain in two undergraduate samples (N = 81; N = 76). Both associations were found indicating a strong criterion validity of the Pain Tolerance scale.