Differential regulation of aortic growth in male and female rodents is associated with AAA development.
BACKGROUND
The objective was to examine effects of gonadal hormone manipulation on aortic diameter and macrophage infiltration in rodents during abdominal aortic aneurysm (AAA) formation.


METHODS
Experiment 1: 17-beta estradiol and testosterone pellets were implanted in male (ME) and female (FT) rats. No pellet was implanted in shams (MES, FTS). Experiment 2: Testes and ovaries were removed from males (MO) and females (FO), respectively. No organs were removed from shams (MOS, FOS). Experiment 3: Male and female rats were orchiectomized and oophorectomized, respectively. Four weeks post-castration, testosterone (MOT) and 17-beta estradiol (FOE) pellets were implanted. Shams underwent castration, but no pellet was implanted (MOTS, FOES). All rats underwent infrarenal aortic infusion with elastase postimplantation/postcastration. Diameters were measured on postoperative d 14. Tissue was stained for macrophages by immunohistochemistry.


RESULTS
Diameter (P = 0.046) and macrophage counts (P = 0.014) decreased in ME compared with shams, but not in females treated with testosterone (FT). Diameter (P = 0.019) and macrophage infiltration (P = 0.024) decreased in MO compared with shams, but not in FO. Diameter increased in MOT compared with MOTS (P = 0.033), but decreased in FOE compared with FOES (P = 0.002). Macrophages decreased in FOE compared with FOES (P = 0.002).


CONCLUSIONS
This study documents a decrease in AAA diameter in males treated with estrogen or undergoing orchiectomy, but no changes in females treated with testosterone or undergoing oophorectomy; and an increase in diameter in MOT and a decrease in FOE. These data suggest that gonadal hormones differentially regulate AAA growth in association with changes in macrophages.
Cho
Brenda S
BS
Department of Biomedical Engineering, Jobst Vascular Research Laboratories, Section of Vascular Surgery, University of Michigan, Ann Arbor, Michigan, USA.
Woodrum
Derek T
DT
Roelofs
Karen J
KJ
Stanley
James C
JC
Henke
Peter K
PK
Upchurch
Gilbert R
GR
D000818:Animals; D001012:Aorta, Abdominal / Q000187:drug effects / Q000473:pathology; D017544:Aortic Aneurysm, Abdominal / Q000139:chemically induced / Q000473:pathology* / Q000517:prevention & control*; D002465:Cell Movement / Q000187:drug effects; D004195:Disease Models, Animal; D004958:Estradiol / Q000494:pharmacology / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D007261:Infusions, Intra-Arterial; D008264:Macrophages / Q000187:drug effects / Q000473:pathology; D008297:Male; D009919:Orchiectomy; D010052:Ovariectomy; D010196:Pancreatic Elastase / Q000008:administration & dosage / Q000009:adverse effects; D010641:Phenotype; D051381:Rats; D017207:Rats, Sprague-Dawley; D013739:Testosterone / Q000494:pharmacology / Q000627:therapeutic use*
D013739:Testosterone; D004958:Estradiol; D010196:Pancreatic Elastase