Norepinephrine microinjections in the hypothalamic paraventricular nucleus increase extracellular dopamine and decrease acetylcholine in the nucleus accumbens: relevance to feeding reinforcement.
Norepinephrine (NE) was microinjected into the paraventricular nucleus (PVN), while microdialysis was used to monitor extracellular dopamine (DA) and acetylcholine (ACh) in the nucleus accumbens (NAc). The PVN is a site where exogenously administered NE can act through alpha 2 receptors to elicit eating behavior and preference for carbohydrates. It was hypothesized that NE in the PVN acts on a behavior reinforcement system by altering the DA/ACh balance in the NAc. NE microinjections (80 nmol in 0.3 microliter), which effectively elicited feeding in satiated rats in a separate test, caused a significant increase in extracellular DA (109%) and decrease in ACh (-27%) when the same animals were tested in the absence of food. In contrast when the food was available and ingested, ACh increased (51%) instead of decreasing. These results support the hypothesis that a functional link exists between the PVN and the NAc in which DA helps initiate and ACh helps stop appetitive behavior involved in the reinforcement of eating.
Hajnal
A
A
Department of Psychology, Princeton University, New Jersey 08544-1010, USA.
Mark
G P
GP
Rada
P V
PV
Lénárd
L
L
Hoebel
B G
BG
D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D004298:Dopamine / Q000378:metabolism*; D004435:Eating / Q000187:drug effects*; D005110:Extracellular Space / Q000378:metabolism; D008297:Male; D017551:Microdialysis; D008845:Microinjections; D009638:Norepinephrine / Q000494:pharmacology*; D009714:Nucleus Accumbens / Q000187:drug effects* / Q000378:metabolism; D010286:Paraventricular Hypothalamic Nucleus / Q000187:drug effects* / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley
D000109:Acetylcholine; D004298:Dopamine; D009638:Norepinephrine