Effects of noradrenergic alpha-2 receptor antagonism or noradrenergic lesions in the ventral bed nucleus of the stria terminalis and medial preoptic area on maternal care in female rats.
BACKGROUND
Maternal behavior in laboratory rats requires a network of brain structures including the ventral bed nucleus of the stria terminalis (BSTv) and medial preoptic area (mPOA). Neurotransmitter systems in the BSTv and mPOA influencing maternal behaviors are not well understood, although norepinephrine is an excellent candidate because the BSTv contains the densest noradrenergic fiber plexus in the forebrain and norepinephrine in the mPOA is known to influence other female reproductive functions.


OBJECTIVE
We hypothesized that downregulated noradrenergic activity in the BSTv and mPOA is necessary for mothering.


METHODS
Postpartum mother-litter interactions were observed after BSTv infusion of yohimbine (an α2 autoreceptor antagonist that increases norepinephrine release), and after BSTv or mPOA infusion of the more selective α2 autoreceptor antagonist idazoxan. Lastly, noradrenergic input to the BSTv/mPOA was selectively lesioned in nulliparous rats with anti-DBH-saporin to determine if this would facilitate mothering.


RESULTS
BSTv yohimbine almost abolished retrieval of pups but did not significantly affect dams' ability to initiate contact, lick, or nurse them. BSTv idazoxan disrupted retrieval somewhat less than yohimbine, but significantly reduced nursing. mPOA idazoxan impaired retrieval more severely than that found after BSTv infusion. Anti-DBH-saporin almost eliminated noradrenergic terminals in the BSTv and reduced them by over 60% in the mPOA, but did not promote maternal responding. It also did not affect females' anxiety-related behavior.


CONCLUSIONS
Downregulated noradrenergic activity in the BSTv and mPOA is necessary for postpartum maternal behavior in rats, but eliminating this system alone is insufficient to promote maternal behaviors in nulliparous females.
Behavioral Neuroscience Program, Department of Psychology, Michigan State University, 108 Giltner Hall, East Lansing, MI 48824, USA.
Carl D
CD
Smith
M Allie
MA
Holschbach
Joshua
J
Olsewicz
Joseph S
JS
Lonstein
D058669:Adrenergic alpha-2 Receptor Antagonists / Q000494:pharmacology*; D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005260:Female; D019329:Idazoxan / Q000494:pharmacology*; D008425:Maternal Behavior / Q000187:drug effects*; D010052:Ovariectomy; D049590:Postpartum Period / Q000187:drug effects / Q000523:psychology; D011301:Preoptic Area / Q000187:drug effects*; D051381:Rats; D020318:Rats, Long-Evans; D054789:Ribosome Inactivating Proteins, Type 1 / Q000494:pharmacology; D000076985:Saporins; D012686:Septal Nuclei / Q000187:drug effects*; D015016:Yohimbine / Q000494:pharmacology*
D058669:Adrenergic alpha-2 Receptor Antagonists; D000911:Antibodies, Monoclonal; D054789:Ribosome Inactivating Proteins, Type 1; C101397:anti-dopamine beta-hydroxylase immunotoxin; D015016:Yohimbine; D000076985:Saporins; D019329:Idazoxan