title: The activation of β2-adrenergic receptors in naïve rats causes a reduction of blood glutamate levels: relevance to stress and neuroprotection.
abstract: This study examines the effects of the activation of β1 and β2-adrenergic receptors on glutamate homeostasis in the blood of naïve rats. Forty five male Sprague-Dawley rats were randomly assigned into one of seven treatment groups that were treated with various β-adrenergic receptor agonist and antagonist drugs. Blood glutamate levels were determined at t = 0, 30, 60, 90, and 120 min. The activation of β1 and β2-adrenergic receptors via isoproterenol hydrochloride administration produced a marked sustained decrease in blood glutamate levels by 60 min after treatment (ANOVA, t = 60, 90 min: P < 0.05, t = 120 min: P < 0.01). Pretreatment with propranolol hydrochloride (a non-selective β-adrenergic receptor blocker) or butaxamine hydrochloride (a selective β2-adrenergic receptor blocker) occluded the isoproterenol-mediated decrease in blood glutamate levels. Propranolol alone had no effect on blood glutamate levels. Selective β1-adrenergic receptor blockade with metoprolol resulted in decreased blood glutamate levels (ANOVA, t = 90 min: P < 0.05, t = 120 min: P < 0.01). Butaxamine hydrochloride alone resulted in a delayed-onset increase in glutamate levels (ANOVA, t = 120 min: P < 0.05). The results suggest that the activation of β2 receptors plays an important role in the homeostasis of glutamate in rat blood.
authors.affiliation: Division of Anesthesiology, Soroka Medical Center, Ben Gurion University of the Negev, Beer-Sheva, Israel. zlotnika@bgu.ac.il
authors.forename: Alexander
authors.initials: A
authors.lastname: Zlotnik
authors.forename: Yael
authors.initials: Y
authors.lastname: Klin
authors.forename: Benjamin F
authors.initials: BF
authors.lastname: Gruenbaum
authors.forename: Shaun E
authors.initials: SE
authors.lastname: Gruenbaum
authors.forename: Sharon
authors.initials: S
authors.lastname: Ohayon
authors.forename: Mathew
authors.initials: M
authors.lastname: Boyko
authors.forename: Eyal
authors.initials: E
authors.lastname: Sheiner
authors.forename: Barak
authors.initials: B
authors.lastname: Aricha-Tamir
authors.forename: Yoram
authors.initials: Y
authors.lastname: Shapira
authors.forename: Vivian I
authors.initials: VI
authors.lastname: Teichberg
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000818:Animals; D002078:Butoxamine / Q000494:pharmacology; D018698:Glutamic Acid / Q000378:metabolism*; D008297:Male; D008790:Metoprolol / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D018343:Receptors, Adrenergic, beta-2 / Q000378:metabolism*; D013312:Stress, Physiological
chemical_list: D000319:Adrenergic beta-Antagonists; D018343:Receptors, Adrenergic, beta-2; D002078:Butoxamine; D018698:Glutamic Acid; D011433:Propranolol; D008790:Metoprolol