COMPARISON OF THE EFFECTS OF 2-DEOXYGLUCOSE AND IMMOBILIZATION ON SECRETION AND SYNTHESIS RATE OF CATECHOLAMINES IN THE ADRENAL-GLAND - A MICRODIALYSIS STUDY IN CONSCIOUS RATS
Ai. Kuzmin et al., COMPARISON OF THE EFFECTS OF 2-DEOXYGLUCOSE AND IMMOBILIZATION ON SECRETION AND SYNTHESIS RATE OF CATECHOLAMINES IN THE ADRENAL-GLAND - A MICRODIALYSIS STUDY IN CONSCIOUS RATS, Acta Physiologica Scandinavica, 155(2), 1995, pp. 147-155
Using microdialysis, extracellular 3,4-dihydroxyphenylalanine (DOPA),
noradrenaline (NA) and adrenaline (AD) concentrations in the adrenal g
land were monitored in conscious rats during and after 60 min of immob
ilization (IMM) as well as after injection of 500 mg kg(-1) 2-deoxyglu
cose (2-DG). IMM produced a rapid and transient increase in secretion
of AD (20-fold), NA (13-fold) and DOPA (3.6-fold). This was accompanie
d by an increase in blood pressure (+18 mmHg) and heart rate (+146 b.p
.m.). Repeated exposure to IMM (daily 60 min, for 5 days) had no influ
ence on either catecholamine secretion of haemodynamic profiles, indic
ating the lack of habituation to stressful conditions. Unlike IMM, the
stress of 2-DG-induced central neuroglucopenia stimulated the release
of AD without affecting NA secretion. AD levels peaked (5.1-fold incr
ease) 40-60 min after 2-DG injection and then slowly declined. 2-DG in
duced no changes in blood pressure but reduced the heart rate (-48 b.p
.m.). In separate experiments, steady-state dialysate DOPA levels, rea
ched during continuous infusion of decarboxylase inhibitor NSD 1015 in
to adrenal gland tissue through the dialysis probe, served as an index
of adrenomedullary tyrosine hydroxylase (TH) activity. IMM evoked a m
arked increase in TH activity (DOPA formation increased 2.7-fold), whi
ch remained elevated 60 min after the cessation of stress when AD and
NA secretion had already fallen to baseline. After 2-DG, despite signi
ficant hormonal response, adrenal TH activity was unchanged. These res
ults give clear evidence that IMM and 2-DG-induced neuroglucopenia may
be considered as two different types of stressful stimuli.