In rats the reward state of the female is unique immediately postpartum; she chooses pups over cocaine. We seek to determine if the neuroendocrine basis of this unique reward state has a biological grounding in which motivation for drug reward is less, and therefore of particular interest for the human condition. We also seek to understand the neural substrate on which the neuroendocrine factors act to alter the reward state of the early postpartum female rat. We use a place preference paradigm that trains the rats to associate particular environmental cues with two unconditioned stimuli, pups and cocaine, and then tests their preference. We will expand this paradigm by systematically testing two variables, the strength of the drug stimulus, and the age of the pup stimulus (Aim 1). We hypothesize that the neuroendocrine status of the female is the basis for the genesis of the unique reward state of the early postpartum period.
In Aim 2, we will test this by applying well-established models of maternal behavior that vary the basis of the behavior. We will (1) use pup-induced maternal behavior in virgin female rats to determine whether maternal status alone (the behavioral state) is sufficient to generate the specialized reward state. Then we will (2) add estrogen, (3) determine whether the hormones of pregnancy alone, in the absence of the hormones and experience of parturition and the postpartum period (maternal pregnant rat hysterectomized-ovariectomized on day 20 of pregnancy), are sufficient, and (4) determine when and if the specialized reward state occurs in pregnancy.
In Aim 3, we will use this unique behavioral model to examine the neural substrate of these reward processes. The neural substrate that is engaged during this specialized reward state of the female will be identified using immunocytochemistry for three dependent variables, c-Fos to determine general engagement/activation of neurons, Homer 1a to identify glutamatergic-related activation, and CART peptide to determine pharmacologic aspects of the activation.

Agency
National Institute of Health (NIH)
Institute
National Institute on Drug Abuse (NIDA)
Type
Research Project (R01)
Project #
5R01DA014025-05
Application #
7194343
Study Section
Integrative, Functional and Cognitive Neuroscience 8 (IFCN)
Program Officer
Wetherington, Cora Lee
Project Start
2003-03-25
Project End
2009-07-31
Budget Start
2007-03-01
Budget End
2009-07-31
Support Year
5
Fiscal Year
2007
Total Cost
$147,442
Indirect Cost
Name
Rutgers University
Department
Type
Organized Research Units
DUNS #
130029205
City
Newark
State
NJ
Country
United States
Zip Code
07102
Pereira, M; Morrell, J I (2011) Functional mapping of the neural circuitry of rat maternal motivation: effects of site-specific transient neural inactivation. J Neuroendocrinol 23:1020-35
Morrell, Joan I; Basso, Julia C; Pereira, Mariana (2011) Both high and low doses of cocaine derail normal maternal caregiving - lessons from the laboratory rat. Front Psychiatry 2:30
Pereira, Mariana; Farrar, Andrew M; Hockemeyer, Jörg et al. (2011) Effect of the adenosine A2A receptor antagonist MSX-3 on motivational disruptions of maternal behavior induced by dopamine antagonism in the early postpartum rat. Psychopharmacology (Berl) 213:69-79
Smith, Kiersten S; Morrell, Joan I (2011) Behavioral differences between late preweanling and adult female Sprague-Dawley rat exploration of animate and inanimate stimuli and food. Behav Brain Res 217:326-36
Pereira, M; Morrell, J I (2010) The medial preoptic area is necessary for motivated choice of pup- over cocaine-associated environments by early postpartum rats. Neuroscience 167:216-31
Seip, Katharine M; Morrell, Joan I (2009) Transient inactivation of the ventral tegmental area selectively disrupts the expression of conditioned place preference for pup- but not cocaine-paired contexts. Behav Neurosci 123:1325-38
Pereira, Mariana; Morrell, Joan I (2009) The changing role of the medial preoptic area in the regulation of maternal behavior across the postpartum period: facilitation followed by inhibition. Behav Brain Res 205:238-48
Seip, Katharine M; Pereira, Mariana; Wansaw, Michael P et al. (2008) Incentive salience of cocaine across the postpartum period of the female rat. Psychopharmacology (Berl) 199:119-30
Seip, Katharine M; Morrell, Joan I (2008) Exposure to pups influences the strength of maternal motivation in virgin female rats. Physiol Behav 95:599-608
Smith, Kiersten S; Morrell, Joan I (2008) Behavioral responses during the initial exposures to a low dose of cocaine in late preweanling and adult rats. Neurotoxicol Teratol 30:202-12

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