Differential rates of glucose metabolism across subregions of the subfornical organ in Brattleboro rats.
We applied [14C]deoxyglucose autoradiography and imaging techniques to determine rates of glucose metabolism in distinct subdivisions of the subfornical organ (SFO) of conscious Brattleboro rats. Seven anatomically-defineD SFO subregions were discerned having metabolic activities that differed from one another by as much as 29% in water-sated Brattleboro rats. The highest metabolic activity was found in the ventromedial zone of central and caudal subregions where previous studies identified the greatest densities of neurons, capillaries, putative angiotensin receptors, and angiotensin-immunoreactive fibers. Homozygous Brattleboro rats had rates of glucose metabolism that were 39-68% greater than those in corresponding SFO subregions of Long-Evans rats; these differences were accentuated by about 50% following 18 h of water deprivation. Exogenous treatment of Brattleboro rats with vasopressin uniformly normalized subregional glucose metabolism in the SFO. In Sprague-Dawley rats, water deprivation over 120 h provoked greater increases in metabolism of ventromedial than of dorsolateral SFO zones in amounts similar to the differences between Long-Evans and Brattleboro rats. The findings identify focal areas of high metabolic activity within subregions of the SFO where central responses are likely initiated to defend against homeostatic disturbances. The data represent further evidence for the probability that angiotensin II, as both hormone and neurotransmitter, is a metabolic stimulant of its target cells in the nervous system.
Shaver
S W
SW
Department of Surgery, Queen's University, Kingston, ON, Canada.
Kadekaro
M
M
Gross
P M
PM
D000809:Angiotensins / Q000378:metabolism; D000818:Animals; D002196:Capillaries / Q000187:drug effects; D005947:Glucose / Q000378:metabolism*; D006579:Heterozygote; D006720:Homozygote; D007091:Image Processing, Computer-Assisted; D009474:Neurons / Q000187:drug effects / Q000378:metabolism; D009490:Neurosecretory Systems / Q000378:metabolism*; D051381:Rats; D011910:Rats, Brattleboro; D011919:Rats, Inbred Strains; D013356:Subfornical Organ / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D014667:Vasopressins / Q000494:pharmacology
D000809:Angiotensins; D014667:Vasopressins; D005947:Glucose