Temporary inactivation of ventral tegmental area neurons with either muscimol or baclofen reversibly disrupts maternal behavior in rats through different underlying mechanisms

Behav Neurosci. 2009 Aug;123(4):740-51. doi: 10.1037/a0016204.


The purpose of this study was to examine the effects of inactivation of ventral tegmental area (VTA) projection neurons, while sparing fibers of passage, on maternal behavior in rats. Because VTA neurons contain GABA-A and GABA-B receptors, the effects of muscimol or baclofen were studied. Although bilateral injections of either drug into the VTA disrupted maternal behavior, it is likely that they did so through different underlying mechanisms. Muscimol disrupted both retrieval of pups and nursing behavior, while causing stereotyped motor activity. Baclofen disrupted retrieval behavior without affecting nursing behavior, and control injections of baclofen into the region dorsal to VTA were ineffective. The effects of VTA baclofen on maternal behavior are similar to the effects of interference with mesolimbic dopamine (DA) function. The case is made that muscimol probably caused a hyperexcitation of VTA DA neurons through a process of disinhibition. In contrast, baclofen may have depressed the activity of all VTA projection neurons, including VTA DA neurons. Baclofen is a promising tool to explore whether medial preoptic area neurons interact with VTA neurons to control active maternal responses.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Analysis of Variance
  • Animals
  • Baclofen / administration & dosage
  • Baclofen / pharmacology*
  • Catheterization
  • Dose-Response Relationship, Drug
  • Female
  • GABA Agonists / administration & dosage
  • GABA Agonists / pharmacology*
  • Grooming / drug effects
  • Maternal Behavior / drug effects*
  • Maternal Behavior / physiology
  • Motor Activity / drug effects
  • Muscimol / administration & dosage
  • Muscimol / pharmacology*
  • Neurons / drug effects
  • Neurons / physiology
  • Rats
  • Time Factors
  • Ventral Tegmental Area / drug effects*
  • Ventral Tegmental Area / physiology


  • GABA Agonists
  • Muscimol
  • Baclofen