Effect of pertussis toxin pretreated centrally on blood glucose level induced by stress.
In the present study, we examined the effect of pertussis toxin (PTX) administered centrally in a variety of stress-induced blood glucose level. Mice were exposed to stress after the pretreatment of PTX (0.05 or 0.1 µg) i.c.v. or i.t. once for 6 days. Blood glucose level was measured at 0, 30, 60 and 120 min after stress stimulation. The blood glucose level was increased in all stress groups. The blood glucose level reached at maximum level after 30 min of stress stimulation and returned to a normal level after 2 h of stress stimulation in restraint stress, physical, and emotional stress groups. The blood glucose level induced by cold-water swimming stress was gradually increased up to 1 h and returned to the normal level. The intracerebroventricular (i.c.v.) or intrathecal (i.t.) pretreatment with PTX, a Gi inhibitor, alone produced a hypoglycemia and almost abolished the elevation of the blood level induced by stress stimulation. The central pretreatment with PTX caused a reduction of plasma insulin level, whereas plasma corticosterone level was further up-regulated in all stress models. Our results suggest that the hyperglycemia produced by physical stress, emotional stress, restraint stress, and the cold-water swimming stress appear to be mediated by activation of centrally located PTX-sensitive G proteins. The reduction of blood glucose level by PTX appears to due to the reduction of plasma insulin level. The reduction of blood glucose level by PTX was accompanied by the reduction of plasma insulin level. Plasma corticosterone level up-regulation by PTX in stress models may be due to a blood glucose homeostatic mechanism.
Department of Pharmacology, Institute of Natural Medicine, College of Medicine, Hallym University, Chuncheon 24252, Korea.
Hong-Won
HW
Suh
Department of Pharmacology, Institute of Natural Medicine, College of Medicine, Hallym University, Chuncheon 24252, Korea.; Adult Stem Cell Research Center in Kangstem Biotech, Seoul National University, Seoul 08826, Korea.
Yun-Beom
YB
Sim
Department of Pharmacology, Institute of Natural Medicine, College of Medicine, Hallym University, Chuncheon 24252, Korea.
Soo-Hyun
SH
Park
Department of Pharmacology, Institute of Natural Medicine, College of Medicine, Hallym University, Chuncheon 24252, Korea.
Naveen
N
Sharma
College of Physical Education, Kookmin University, Seoul 02707, Korea.
Hyun-Ju
HJ
Im
Department of Physical Education, College of Natural Science, Hallym University, Chuncheon 24252, Korea.
Jae-Seung
JS
Hong
Blood glucose; Cold-water swimming stress; Emotional stress-Physical stress; Pertussis toxin-sensitive G proteins; Restraint stress