Increased dopamine transporter function as a mechanism for dopamine hypoactivity in the adult infralimbic medial prefrontal cortex following adolescent social stress. (October 2015)

• Record Type: Journal Article
• Authors: Novick, Andrew M.; Forster, Gina L.; Hassell, James E.; Davies, Daniel R.; Scholl, Jamie L.; Renner, Kenneth J.; Watt, Michael J.
• Is Part Of: Neuropharmacology. Volume 97(2015)
• Page Start: 194
• Page End: 200
• Publication Date: 2015-10
• Subjects: Adolescent stress -- Dopamine -- Prefrontal cortex -- Dopamine transporter; Neuropsychopharmacology -- Periodicals; Autonomic Agents -- Periodicals; Neuropsychopharmacologie -- Périodiques; Neuropsychopharmacology; Periodicals; Electronic journals; 615.78
• DOI: 10.1016/j.neuropharm.2015.05.032
• Languages: English
• ISSNs: 0028-3908

Abstract

Abstract: Being bullied during adolescence is associated with later mental illnesses characterized by deficits in cognitive tasks mediated by prefrontal cortex (PFC) dopamine (DA). Social defeat of adolescent male rats, as a model of teenage bullying victimization, results in medial PFC (mPFC) dopamine (DA) hypofunction in adulthood that is associated with increased drug seeking and working memory deficits. Increased expression of the DA transporter (DAT) is also seen in the adult infralimbic mPFC following adolescent defeat. We propose the functional consequence of this increased DAT expression is enhanced DA clearance and subsequently decreased infralimbic mPFC DA availability. To test this, in vivo chronoamperometry was used to measure changes in accumulation of the DA signal following DAT blockade, with increased DAT-mediated clearance being reflected by lower DA signal accumulation. Previously defeated rats and controls were pre-treated with the norepinephrine transporter (NET) inhibitor desipramine (20 mg/kg, ip.) to isolate infralimbic mPFC DA clearance to DAT, then administered the selective DAT inhibitor GBR-12909 (20 or 40 mg/kg, sc.). Sole NET inhibition with desipramine produced no differences in DA signal accumulation between defeated rats and controls. However, rats exposed to adolescent social defeat demonstrated decreased DA signal accumulation compared to controls in response to both doses of GBR-12909, indicating greater DAT-mediated clearance of infralimbic mPFC DA. These results suggest that protracted increases in infralimbic mPFC DAT function represent a mechanism by which adolescent social defeat stress produces deficits in adult mPFC DA activity and corresponding behavioral and cognitive dysfunction. Highlights: Adolescent defeat results in less prefrontal dopamine accumulation upon transporter blockade. Lower dopamine accumulation suggests greater dopamine transporter function. Targeting dopamine transporters may rectify negative effects of adolescent stress.