title: Effect of estrogens on blood glutamate levels in relation to neurological outcome after TBI in male rats.
abstract: OBJECTIVE
  Estrogen has been shown to possess neuroprotective properties both in vitro and in vivo. Traumatic brain injury (TBI) in ovulating females results in favorable neurological outcomes when compared to males with similar insults. The brain-to-blood glutamate gradient removes excess glutamate from brain extracellular fluids (ECF). Enhancing this gradient leads to improved neurological outcomes following TBI. In this study we investigate the effect of female gonadal steroids on blood glutamate levels and neurological outcomes.
  
  
  METHODS
  Forty male Sprague-Dawley rats were assigned to one of five groups: (1) sham, (2) Premarin treatment, (3) TBI, (4) TBI + Premarin treatment, and (5) TBI + Premarin pretreatment. TBI was induced, and estrogen and glutamate levels were determined at 0, 60, 120, 135, and 150 min. Neurological recovery was evaluated using the Neurological Severity Score (NSS) at 1 h and reassessed at 24 h post TBI.
  
  
  RESULTS
  Premarin treatment groups demonstrated a decline in blood glutamate levels by 60 min. This decline was found to be more pronounced in the TBI + Premarin group, which maintained the decline throughout the experiment. At 120 min, the difference between groups was most pronounced (TBI + Premarin 99 ± 36 μM/l vs. control 200 ± 46 μM/l, p < 0.01). Neurological recovery was significantly better in the Premarin treatment group (NSS at 24 h 6 ± 1 vs. control 11 ± 1).
  
  
  CONCLUSIONS
  Premarin injected into male rats significantly decreases blood glutamate levels in rats suffering TBI. This decrease is associated with improved neurological outcomes, thus implicating the role of estrogen in neuroprotection.
authors: Department of Anesthesiology and Critical Care, Soroka University Medical Center, Ben-Gurion University of the Negev, Beer Sheva, Israel.
authors: Alexander
authors: A
authors: Zlotnik
authors: Akiva
authors: A
authors: Leibowitz
authors: Boris
authors: B
authors: Gurevich
authors: Sharon
authors: S
authors: Ohayon
authors: Matthew
authors: M
authors: Boyko
authors: Moti
authors: M
authors: Klein
authors: Boris
authors: B
authors: Knyazer
authors: Yoram
authors: Y
authors: Shapira
authors: Vivian I
authors: VI
authors: Teichberg
mesh_terms: D000818:Animals; D001930:Brain Injuries / Q000188:drug therapy* / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004967:Estrogens / Q000008:administration & dosage / Q000494:pharmacology*; D004966:Estrogens, Conjugated (USP) / Q000008:administration & dosage / Q000494:pharmacology*; D005971:Glutamates / Q000097:blood*; D008297:Male; D018696:Neuroprotective Agents / Q000008:administration & dosage / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D016896:Treatment Outcome
chemical_list: D004967:Estrogens; D004966:Estrogens, Conjugated (USP); D005971:Glutamates; D018696:Neuroprotective Agents