In vivo release of interleukin-1 beta into hypothalamic extracellular fluid in rats: effects of repeated sampling.
Interleukin-1 beta (Il-1 beta) concentrations in extracellular fluid (ECF) withdrawn at 10-min intervals through a push-pull cannula (PPC) located in the hypothalamus were studied in freely behaving male rats for 1 h at 24 and 72 h and again at 7 days after PPC implantation. Il-1 beta concentrations in ECF were similar in the latter. However, when ECF was sampled at 3 h and again 7 days after PPC implantation, Il-1 beta concentrations were greatly elevated at 7 days when compared to all other intervals. These results demonstrate how the relationships between Il-1 beta measured in ECF and the conditions of measurement appear to be integral parts of a whole intracerebral system: cytokine concentrations appear to be inextricably bound to intrahypothalamic conditions created by the sampling device presence and frequency of use.
Department of Anatomy, University of South Florida, College of Medicine, Tampa 33612-4799, USA.
C P
CP
Phelps
A
A
Sahu
J
J
Oliver
X L
XL
Ma
P S
PS
Kalra
S P
SP
Kalra
R A
RA
Menzies
L
L
Chen
M
M
Denker
E
E
Horvath
D000818:Animals; D002408:Catheters, Indwelling; D005110:Extracellular Space / Q000378:metabolism*; D007031:Hypothalamus / Q000378:metabolism*; D007375:Interleukin-1 / Q000378:metabolism*; D008297:Male; D010477:Perfusion; D051381:Rats
D007375:Interleukin-1