title: Motherhood and the hormones of pregnancy modify concentrations of hippocampal neuronal dendritic spines.
abstract: Short-term fluctuations in steroid hormones such as estradiol (E2) and progesterone (P) can affect the concentration of hippocampal dendritic spines in adult, cycling nulliparous female rats. Pregnancy is characterized by a significantly longer duration of substantially elevated E2 and P compared to the estrous cycle. Thus, even greater changes than those reported during estrus may be evident. In two experiments, we examined the extent to which reproductive and hormonal state altered the concentration of apical neuronal dendritic spines of the CA1 region of the hippocampus in the following age-matched groups (N's = 7-10/group) of rats: in Exp. 1., CA1 dendritic spine density was examined in nulliparous diestrus (DES), proestrus (PRO), and estrus (ES) females, and late-pregnant (LP) (day 21) and lactating (day 5-6; LACT) females. In Exp. 2, the effects on spine density of a regimen mimicking pregnancy (and that stimulates maternal behavior) were examined, using ovariectomized, no hormone-exposed (OVX-minus) vs. sequential P&E(2)-treated (OVX + P&E2) groups. For both experiments, brains were removed, Golgi-Cox-stained and the most lateral tertiary branches of the apical dendrite of completely-stained hippocampal CA1 pyramidal neurons were traced with oil-immersion at x 1600 and dendritic spine density (# spines/10 micro dendritic segment) recorded. In Exp. 1, spine density was increased in LP and LACT females (which were not different) compared to the other virgin groups, including PRO females, who had more spines than DES and ES. In Exp. 2, OVX + P&E2 displayed significantly more dendritic spines per 10 micro than OVX-minus females (and had numbers that were similar to those of LP and LACT from Exp. 1). Pregnancy and its attendant hormonal fluctuations, therefore, may alter hippocampal neurons that regulate some non-pup-directed components of maternal behavior (e.g., nest building) or behaviors that support maternal behavior (e.g., foraging, associative memory).
authors: Department of Psychology-Center for Neuroscience, 103 Richmond Hall, University of Richmond, VA 23173, USA. ckinsley@richmond.edu
authors: Craig H
authors: CH
authors: Kinsley
authors: Regina
authors: R
authors: Trainer
authors: Graciela
authors: G
authors: Stafisso-Sandoz
authors: Princy
authors: P
authors: Quadros
authors: Lori Keyser
authors: LK
authors: Marcus
authors: Christa
authors: C
authors: Hearon
authors: Elizabeth Ann Amory
authors: EA
authors: Meyer
authors: Naomi
authors: N
authors: Hester
authors: Melissa
authors: M
authors: Morgan
authors: Frederick J
authors: FJ
authors: Kozub
authors: Kelly G
authors: KG
authors: Lambert
mesh_terms: D000818:Animals; D004396:Coloring Agents; D049229:Dendritic Spines / Q000502:physiology* / Q000648:ultrastructure; D030762:Estrous Cycle / Q000502:physiology; D005260:Female; D006624:Hippocampus / Q000166:cytology / Q000502:physiology*; D006728:Hormones / Q000494:pharmacology*; D007091:Image Processing, Computer-Assisted; D007774:Lactation / Q000502:physiology; D010052:Ovariectomy; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D004396:Coloring Agents; D006728:Hormones