TY - JOUR
T1 - Alterations in blood glucose levels under hyperinsulinemia affect accumbens dopamine
AU - Bello, Nicholas T.
AU - Hajnal, Andras
N1 - Funding Information:
The authors would like to thank Drs. C.H. Lang and I.A. Simpson for their technical advice on the hyperinsulinemic–glycemic clamping technique, Dr. W. M. Margas for his assistance with the HPLC system and N. Horvath for her assistance with histology. This data was presented at the meeting of the Society for the Study of Ingestive Behavior, 2005, Pittsburgh, PA, USA. This research was supported by NIH grants DK065709 and NS046872.
PY - 2006/6/15
Y1 - 2006/6/15
N2 - Dopaminergic systems have been implicated in diabetes and obesity. Notwithstanding, the most basic relationship between dopamine and plasma insulin as well as glucose levels yet remains unknown. The present experiments were designed to investigate the effects of acute hyperinsulinemia on basal dopamine levels in the nucleus accumbens of the rat under chloral hydrate anesthesia using acute microdialysis in combination with the hyperinsulinemic-glycemic clamping procedure. In Experiment 1, each rat was infused with one of the three concentrations of insulin (2.4, 4.8, or 9.6 mU/kg per min) while plasma glucose levels were maintained at euglycemia (∼ 5.5 mmol/L). Dopamine, dihydroxyphenylacetic acid and homovanillic acid were not significantly different from baseline during either the clamp or post-clamp periods for all insulin concentrations. In Experiment 2, rats were infused with the highest concentration of insulin (9.6 mU/kg per min) and plasma glucose levels were maintained at either hypoglycemia (∼ 3 mmol/L) or hyperglycemia (∼ 14 mmol/L). Dopamine was elevated at 100 min (+ 113% above basal levels) and 120 min (+ 117%) in the hypoglycemic condition and at 120 min (+ 121%) in the hyperglycemic condition. In the hyperglycemic post-clamp period, homovanillic acid was decreased below basal levels (approximately - 32%). These results together suggest that short-term blood glucose deviations coupled with acute hyperinsulinemia affect the mesoaccumbens dopamine system.
AB - Dopaminergic systems have been implicated in diabetes and obesity. Notwithstanding, the most basic relationship between dopamine and plasma insulin as well as glucose levels yet remains unknown. The present experiments were designed to investigate the effects of acute hyperinsulinemia on basal dopamine levels in the nucleus accumbens of the rat under chloral hydrate anesthesia using acute microdialysis in combination with the hyperinsulinemic-glycemic clamping procedure. In Experiment 1, each rat was infused with one of the three concentrations of insulin (2.4, 4.8, or 9.6 mU/kg per min) while plasma glucose levels were maintained at euglycemia (∼ 5.5 mmol/L). Dopamine, dihydroxyphenylacetic acid and homovanillic acid were not significantly different from baseline during either the clamp or post-clamp periods for all insulin concentrations. In Experiment 2, rats were infused with the highest concentration of insulin (9.6 mU/kg per min) and plasma glucose levels were maintained at either hypoglycemia (∼ 3 mmol/L) or hyperglycemia (∼ 14 mmol/L). Dopamine was elevated at 100 min (+ 113% above basal levels) and 120 min (+ 117%) in the hypoglycemic condition and at 120 min (+ 121%) in the hyperglycemic condition. In the hyperglycemic post-clamp period, homovanillic acid was decreased below basal levels (approximately - 32%). These results together suggest that short-term blood glucose deviations coupled with acute hyperinsulinemia affect the mesoaccumbens dopamine system.
UR - http://www.scopus.com/inward/record.url?scp=33646923746&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=33646923746&partnerID=8YFLogxK
U2 - 10.1016/j.physbeh.2006.03.027
DO - 10.1016/j.physbeh.2006.03.027
M3 - Article
C2 - 16678226
AN - SCOPUS:33646923746
SN - 0031-9384
VL - 88
SP - 138
EP - 145
JO - Physiology and Behavior
JF - Physiology and Behavior
IS - 1-2
ER -