title: Norepinephrine microinjections in the hypothalamic paraventricular nucleus increase extracellular dopamine and decrease acetylcholine in the nucleus accumbens: relevance to feeding reinforcement.
abstract: 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.
authors.affiliation: Department of Psychology, Princeton University, New Jersey 08544-1010, USA.
authors.forename: A
authors.initials: A
authors.lastname: Hajnal
authors.forename: G P
authors.initials: GP
authors.lastname: Mark
authors.forename: P V
authors.initials: PV
authors.lastname: Rada
authors.forename: L
authors.initials: L
authors.lastname: Lénárd
authors.forename: B G
authors.initials: BG
authors.lastname: Hoebel
mesh_terms: 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
chemical_list: D000109:Acetylcholine; D004298:Dopamine; D009638:Norepinephrine