Citation

Holschbach MA, Vitale EV, Lonstein JS. Behav. Brain Res. 2018; 348: 53-64.

Affiliation

Neuroscience Program, 108 Giltner Hall, Michigan State University, East Lansing, MI, 48824, USA; Department of Psychology, 108 Giltner Hall, Michigan State University, East Lansing, MI, 48824, USA. Electronic address: Lonstein@msu.edu.

Copyright

(Copyright © 2018, Elsevier Publishing)

DOI

10.1016/j.bbr.2018.04.008

PMID

29653128

Abstract

The behavioral modifications associated with early motherhood, including high aggression, caring for young, and low anxiety are all affected by acute pharmacological manipulation of serotonin signaling. However, the effects on these behaviors of permanently disrupting serotonin signaling at one of its primary sources, the dorsal raphe (DR), have not been examined in detail. To address this, serotonin-specific lesions centered on the dorsomedial DR (DRdm; subregion most implicated in emotional behaviors) were induced at mid-pregnancy (day 15) or early postpartum (day 2) in rats using a saporin-conjugated neurotoxin targeting the serotonin transporter (Anti-SERT-SAP). Prepartum or postpartum Anti-SERT-SAP reduced DRdm serotonin immunoreactivity by ~40-65%, and postpartum Anti-SERT-SAP also reduced it in the ventromedial and lateral wings of the DR, as well as the median raphe. Serotonin-immunoreactive fibers were significantly reduced in the anterior hypothalamus, but not medial preoptic area, of lesioned dams. Pre- and postpartum lesions both greatly reduced maternal aggression, but while prepartum lesions did not affect later undisturbed maternal caregiving, the larger postpartum lesions prevented the postpartum decline in kyphotic nursing and reduced pup licking. Serotonin lesions did not affect pup retrieval, but the prepartum lesions temporarily increased maternal hovering over and licking the pups observed immediately after the disruptive retrieval tests. Dams' anxiety-like behaviors and litter weight gains were unaffected. These findings suggest that DRdm serotonin projecting to the AH is particularly critical for maternal aggression, but that more widespread disruption of midbrain raphe serotonin is necessary to greatly impair maternal caregiving. Postpartum anxiety may rely more on other neurochemical systems or different midbrain serotonergic cell populations.

Copyright © 2018. Published by Elsevier B.V.

Language: en

Keywords

aggression; anxiety; lactation; maternal behavior; pregnancy; serotonin