Download Plasma Adrenaline Concentration is Lower in Post

Clinical Science (1994) 87. 69-74 (Printed in Great Britain)
69
Plasma adrenaline concentration is lower in post-obese
than in never+bese women in the basal state, in response
to sham-feeding and after food intake
H. BRYDE ANDERSEN', A. RABENI, A. ASTRUP' and N. JUEL CHRISTENSEN'
'Department of Internal Medicine and Endocrinology, Herlev Hospital, University
of Copenhagen. Copenhagen, Denmark, and 'The Research Department of Human
Nutrition, Centre for Food Research, The Royal Veterinary and Agricultural University,
Frederiksberg, Denmark
(Received 24 September 1993/13 january 1994; accepted 3 February 1994)
1. Plasma
pancreatic polypeptide, plasma catecholamine, blood glucose, plasma insulin and plasma
peptide YY concentrations were studied to assess
differences between eight formerly obese and eight
never-obese control women during 25 min of shamfeeding (with the sight and smell of an English
breakfast) and for 5 h after they had ingested the
meal (3514kJ, 50% fat, 35% carbohydrate). The
post-obese women had maintained their normal body
weight for at least 3 months before the study.
2. The plasma noradrenaline concentration was not
different between the groups either during fasting
(post-obese women 0.08 f 0.01 ng/ml versus control
women 0.10f0.01 ng/ml) or in the significant postprandial increase (P<O.001). The plasma adrenaline
concentration increased significantly during shamfeeding in the control group from 0.024 f 0.004 ng/ml
to 0.033f0.004ng/ml (P=O.O2) in contrast with the
post-obese women, who had significantly lower
plasma concentrations of adrenaline in the fasting
state (post-obese 0.016f 0.003 ng/ml versus control
women 0.024 f 0.004 ng/ml, P=0.003), during shamfeeding (post-obese women 0.018 f 0.002 ng/ml versus
control women 0.033 f 0.004ng/ml, P= 0.003) and in
the postprandial increase (P=0.003). The maximal
postprandial response concentrations recorded 5 h
after the meal were 0.025 f 0.003 ng/ml in post-obese
women and 0.035 f 0.004 ng/ml in control subjects
(P=0.04). There were no significant differences in
plasma pancreatic polypeptide, plasma peptide YY,
plasma insulin, or blood glucose concentrations between the two groups.
3. The plasma adrenaline concentration is lower in
post-obese women in the basal fasting state, during
sham-feeding and in response to a meal. These results
indicate that post-obese subjects respond differently
to food stimulation than normal subjects.
INTRODUCTION
Sham-feeding (the sight and smell of a meal but
not the taste) induces several responses in normal
subjects [1-31. Pancreatic polypeptide originates
from the PP-cells of the endocrine pancreas and its
secretion is primarily under vagal control. Plasma
concentrations of pancreatic polypeptide increase
during sham-feeding and to a large degree after a
meal [4]. Peptide YY is a gastrointestinal peptide
primary localized to the ileum. It increases after a
meal [5]. Peptide YY has inhibitory effects in the
late postprandial phase. Previous studies have suggested that gastrointestinal and hormonal responses
to sham-feeding may be abnormal in obese subjects,
but the results are conflicting [6-81.
The aim of the present study was to assess
differences in plasma concentrations of pancreatic
polypeptide, catecholamines and peptide YY
between formerly obese and never-obese women
during sham-feeding and after food intake.
METHODS
Eight post-obese women and eight never-obese
matched control women were studied in the morning after a 10 h overnight fast following 2 days of a
weight maintenance carbohydrate-rich diet (30% fat,
58% carbohydrate and 12% protein). Table 1 shows
the demographic data of the two groups. Lean body
mass was calculated by the whole body bioimpedance method using an Animeter (HTSEngineering, Odense, Denmark) and the equation
given by Heitmann [9]. The post-obese women had
maintained their normal weight for at least 3
months after a diet-induced mean weight loss of
23.5 kg.
On the day of the investigation, a cannula was
inserted into a hand vein, and the subjects rested for
1 h in the supine position with 45" elevated head tilt
before the study began. Blood samples were taken
as arterialized venous samples, as the hand was
placed in a device supplying hot air (55-60°C)
Key words: adrenaline, digestive physiology, noradrenaline, pancreatic polypeptide, peptide YY, postobese women.
Correspondence: Dr H. Bryde Anderren. Department of Internal Medicine and Endocrinology, Herlev Hospital, University of Copenhagen, DK-2730 Herlev, Denmark.
H. Bryde Andenen et al.
70
Table I. Demographic data of the eight port-obere women and the
eight never-obese control women. Values are means fSEM.
Body mass index (kgiml)
Age (years)
Fat-free mass (kg)
Postobese
women
Never-abese
control
women
21.5 f I .2
37.4kl.b
4 7 . 2 k 1.5
I .4
31.5 f9.8
41.5 3.5
22.8
during the entire test period (Technical Department,
University of Nottingham, Nottingham, U.K.). The
samples were collected at times -35 and -5min
before stimulation with the sight and smell of the
test meal. The meal consisted of scrambled egg,
bacon, coffee, milk, juice and open sandwiches with
cheese and jam to a total energy content of
3514kJ, comprising as 15% protein, 50% fat and
35% carbohydrate. Samples were taken after 10, 15
and 20 min of sham-feeding. After 25 min of shamfeeding the subjects ingested the food (without the
coffee) during 17.5f 1.0min (post-obese women,
18.8k 1.3min; never-obese women, 16.3f 1.4 min).
Blood pressure was recorded and blood samples
were drawn at 15, 30, 45, 60, 75, 90, 105, 120, 150,
180, 195, 210, 225, 240, 270 and 300min after the
meal. Blood samples were analysed for glucose
using a standard enzymic method; plasma samples
were analysed for pancreatic polypeptide, insulin
and peptide Y Y using radioimmunoassays and for
catecholamines by a radioenzymic assay.
The study included measurements of metabolic
rate by a ventilated hood system, recordings of
subjective hunger and satiety sensations by ratings
on visual analogue scales and analyses of blood
lipid concentrations [9a].
The study was approved by the local ethics
committee, and was conducted in accordance with
the Helsinki Declaration 11. All subjects were studied after giving their informed consent.
Assays
Glucose. Blood glucose was analysed by a
standard enzymic method [lo].
Peptide hormones. Blood samples were drawn into
ice-chilled tubes containing 500 i.u. of heparin
sodium (DAK) and 5 x lo6 i.u. aprotinin (Trasylol;
Bayer) per lOml of blood and immediately centrifuged.
Plasma insulin was assayed by radioimmunoassay
using antibody M8309, tracer ''1 (Tyr A19)-human
insulin (Novo Nordisk, Denmark) and human insulin standard (Novo BioLabs, Denmark). Insulin was
assayed after polyethyleneglycol precipitation as described by Heding [1 13. The intra-assay coefficient
of variation was 15% at low concentrations (3411 1 pmol/l, n=26) and 4% at the higher concentration level (149-571 pmol/l, n=24). The interassay coefficient of variation was 20% and 8% at
87 pmol/l and 506 pmol/l, respectively (n = 11).
Plasma pancreatic polypeptide was measured
using the radioimmunoassay described by Schwartz
et al. [I123 with the following modifications: phosphate buffer (0.04mmol/l, pH 7.4) containing, in
addition, 1 g of human plasma albumin/l and 0.24g
of thimerosal/l was used. The samples and standards
were incubated in two steps: first a 50pl sample
with loop1 of antibody at 4°C for 24h and then
after the addition of IOOpI of radioactive tracer the
samples were incubated at 4°C for a further 24h.
Separation was performed with 250p1 of dextran
(1.6 g/l)-coated charcoal (16 g/l). The inter-assay
coefficient of variation was 13% at a mean concentration of 14pmol/l (n=40), 11% at 20pmol/l
(n = 37) and 8% at 50 pmol/l (n= 36). The intra-assay
coefficient of variation was 11% at a mean concentration of 15pmol/l, 14% at a mean concentration of
23 pmol/l ( n = 10) and 4% at a mean concentration
of 52pmol/l. The detection limit was calculated
according to RiaCalc (Wallac AS, Allerprd,
Denmark) to be 3pmol/l. Unspecific binding without antibody was 0.5-2%. Anti-porcine pancreatic
polypeptide serum K 5418 was used as antibody
and '251-porcine pancreatic polypeptide was used as
tracer (Novo Nordisk, Bagsvaxd, Denmark).
Human pancreatic polypeptide (PP-05-3943A,
Cambridge Research Biochemicals) was used as the
standard. Samples with high concentrations were
diluted to the assay level.
Plasma peptide YY was measured by radioimmunoassay as described in [12a]. In this study we
have shown that the increase in plasma neuropeptide Y-like immunoreactivity in response to food
intake is due to an increase in the plasma peptide
YY concentration, whereas the plasma neuropeptide
Y concentration did not change.
Catecholamines. These were determined by radioenzymic assay. The blood was sampled in separate
tubes and stored at - 80°C. Plasma noradrenaline
and adrenaline were measured by a single-isotope
derivative technique [ 131. The intra-assay coeficients of variation for noradrenaline and adrenaline
in samples containing normal basal values were 6%
and 8%, respectively ( n = 10). Corresponding values
of inter-assay coefficients of variation for noradrenaline and adrenaline were 7% and 11%, respectively
( n = 10). The sensitivity of the assay, calculated as
three times the SD of the analytical blank, was for
intra-assays 0.3 pg and 0.5 pg/assay for adrenaline
and noradrenaline, respectively. Corresponding
values for interassays were 0.5 pg/assay for both
adrenaline and noradrenaline.
Blood samples from a given test day and subject
were always analysed in the same assay run to
reduce the influence of interassay variation.
Statistical analysis
All results are presented as meansf SEM, unless
stated otherwise. Statistical evaluation was performed using the Mann-Whitney U-test for comparison of basal values, of sham-feeding values and of
71
Plasma adrenaline and post-obesity
o'20
1
0.05
0.04
1
1
-
P=O.O2
-e 0.03
1
E
M
c
8
Meal
Sham
m
0.01
1
0.00
-60 -30
Fig. I. Pluma concentrations of noradrenaline in eight postobese
women
and in eight neverobese control women (0).
Shamfeeding was from time - 25 min to 0 min. Food intake was from time 0 rnin.
Values are means kSEM.
(m)
incremental areas between the two groups. Friedman analyses were used for comparison within each
group. Two-way repeated measures analysis of variance on one factor was used for comparison of the
plasma concentrations and time between the groups
(Sigmastat 1.0, Jandel Scientifics, GmbH, Erkrath,
Germany). The level of statistical significance was
set at P <0.05 (two-tailed).
RESULTS
Fasting plasma noradrenaline concentrations were
not statistically different in post-obese women than
in never-obese control women. Both groups showed
a small increase in plasma noradrenaline concentration during sham-feeding (P= 0.06) and a
significant increase after the meal (P<O.Ol, Fig. 1).
The postprandial peak value at 90min was not
different between the groups. Two-way repeated
measures analysis of variance on noradrenaline revealed no statistically significant difference between
post-obese women and control women (P=O.l),
whereas a statistically significant difference was
found in the different levels of time (P<O.001).
There was no statistically significant interaction
between never-obese control women, post-obese
women and time.
The most striking difference between the two
groups was seen in the plasma adrenaline concentration. Mean plasma adrenaline concentrations
were significantly higher in control women than in
Meal
Sham
0
30
60
I20 150
Time (min)
90
180
210
240
270
Fig. 2. Pluma concentrations of adrenaline in eight post-obese
women (m) and in eight neverobese control women (0).Values
were significantly lower in the eight postobese women (analysis of variance
for all values gave P=O.W3). Specific comparison between the groups for
fasting values and for peak sham-feeding values gave P=0.003 for both.
Sham-feeding was from time -25min to Omin. Food intake was from time
Omin. Values are meanskSEM.
post-obese women (P=0.003). In both groups the
plasma adrenaline concentration increased with time
(P<O.001) with no signs of interaction (P=O.98).
Comparison of the three plasma concentrations
during sham-feeding and the concentration before
sham-feeding (Friedman analyses) revealed a significant increase in the control group only (P=0.02),
whereas the plasma adrenaline concentration in the
post-obese group remained unchanged during shamfeeding (P=O.7) (Fig. 2).
The post-obese subjects had significantly lower
plasma adrenaline concentrations both in the basal
period (P = 0.003), in peak sham-feeding period
(P=O.O03) and in the postprandial response evaluated by the area method and by analysis of
variance (P= 0.003). The significant postprandial
increase followed a parallel pattern in the two
groups (Fig. 2). The maximal postprandial response
values recorded in the post-obese group 5 h after the
meal barely reached the basal level in the control
group. The mean plasma adrenaline concentration
in the post-obese women was approximately 40% of
that in the control subjects.
There was no significant difference in the increase
in plasma polypeptide concentration during shamfeeding between the two groups. After the meal the
first phase response of pancreatic polypeptide was
similar in the two groups, whereas the second phase
300
H. Bryde Andenen et al.
72
250
1
*1
3
600
n .
V
.
-60
-30
0
Sham
550
500
30
60
90
I20
150
1
Meal
Sham
-
1
180
Time (min)
Meal
Fig. 3. Plasma concentrations of pancreatic polypeptide during
shamfeeding and food intake in eight postobese women (W) and
Sham-feeding was from time
in eight never4ese control women (0).
-2Smin to Omin. Food intake was from time Omin. Values are
means fSEM.
response was slightly but not significantly reduced
in the post-obese women (Fig. 3).
There were no differences between the two groups
in the palatability scores for aroma, palatability,
appearance or taste of the meal.
Blood glucose and plasma insulin concentrations
were not significantly different in post-obese women
compared with control women (Fig. 4).
Blood pressure and heart rate were very similar in
the two groups. Both groups showed increased
heart rate and decreased diastolic blood pressure
during the first 30-60min after the meal (Fig. 5).
There was no difference in plasma concentrations
of peptide YY between the post-obese women and
the control women either in the fasting state or in
response to the meal (Fig. 6). The significant postprandial increase started 15 min after the beginning
of food intake to peak values 2 h after the meal
(P<O.ooOOl, Fig. 6). Basal values and the 2 h postprandial response averaged 4.8 f0.5 and 16.8 & 2.1
pmol/l in the post-obese women and 4.1 f0.7 and
14.0f 2.8 pmol/l in the control women. No changes
were seen during sham-feeding (Fig. 6).
DISCUSSION
The present study shows that plasma adrenaline
concentration is abnormally low at rest, during
sham-feeding and in the post-prandial period in
post-obese women as compared with control
women. These findings are in accordance with our
previous published study of the early response to a
Meal
Sham
Fig. 4. Plasma insulin and blood glucose concentrations in eight
post-obese women (W) and in eight neverobese control women
(0).
Shamfeeding was from time -25min to Omin. F w d i n ~ was
e
from time Omin. Values are meansfSEM.
meal in post-obese women [14]. Plasma noradrenaline concentration responses were not, however,
significantly different in post-obese and control
women. We have in several studies observed that
the plasma noradrenaline concentration is reduced
in obese females [15-171 compared with normal
weight control females, but it appears that this
abnormality is normalized by weight reduction.
Interestingly, a low plasma and/or low urinary
adrenaline excretion in obese subjects has been
reported in several studies [18]. The low adrenaline
could be a primary abnormality in obesity in the
sense that it is also present in post-obese subjects.
The main metabolic role of adrenaline is to assist in
the transition of the metabolism from glucose oxidation to fat oxidation by mobilization of free fatty
acids from deposits and by inhibition of insulininduced glucose oxidation. Recent studies in postobese subjects have showed impaired suppression of
carbohydrate oxidation during a high-fat diet
[18a]. At present, it is unclear whether the small,
Plasma adrenaline and post-obesity
i]
i
40
1
loo4
0
90 110 150
Time (min)
180 210 240 170
Fig. 5. Blood pressure and heart rate in eight postobese women
(m)and in eight neverobese control women (0).Shamfeeding was
from time -25min to Omin. Food intake was from time Omin. Values are
means SEM.
1
d
c
8
10
P
Y
z
+
(0
E
5
but definitely abnormal, plasma adrenaline concentrations observed in post-obese subjects contributes
to this abnormality, but it deserves further
investigation.
We observed another abnormality in the plasma
adrenaline concentration in post-obese subjects.
During sham-feeding their plasma adrenaline concentration did not increase, in contrast to the
control subjects. The increase in adrenaline during
sham-feeding is an arousal reaction to the sight and
smell of food, and this arousal reaction was therefore smaller in post-obese subjects than in control
subjects. This may indicate that subjects with weight
problems cannot, to the same extent as control
subjects, distinguish between situations with and
without food stimulation. This abnormal arousal
response may play a significant role in the greater
food intake observed in obese subjects, but again
further studies are required to elucidate this
abnormality.
An important point in this study may be that
blood samples for adrenaline measurements were
obtained while the hand was placed in an airheating box during the entire test period. In previous studies on normal subjects we have measured
plasma concentrations of catecholamines during
sham-feeding in venous blood samples and did not
observe significant increase in adrenaline. It is well
known that the extraction of adrenaline across the
forearm is relatively high and increases with increasing arterial plasma adrenaline concentrations.
Small changes in arterial plasma adrenaline concentrations may therefore not be detected in venous
blood and some investigations require arterial or
arterialized venous blood sampling [191.
Apart from the abnormality in the plasma adrenaline concentration, the metabolic and hormonal
profile in post-obese subjects was very similar to
that observed in control subjects. In a previous
study from our laboratory using h.p.1.c. for the
separation of plasma neuropeptide Y, related peptides and fragments, we found that the increase in
neuropeptide Y-like immunoreactivity activity observed after food intake is due to an increase in the
plasma peptide YY concentration [12al. We found
no difference in the plasma peptide YY concentration between the two groups, but the increase in
the plasma peptide YY concentration observed after
food intake is in accordance with previously published results [20].
In conclusion, our study indicates that the plasma
adrenaline concentration is markedly abnormal in
post-obese women at rest, during sham-feeding and
in the postprandial period. The significance of this
abnormality in the development of obesity deserves
further investigation.
i
0 30 60
N10
-60 -30
=I
73
-
Meal
Sham
ACKNOWLEDGMENTS
We thank Lis Bulow, Inger Hansen, Inge
Timmermann and Bente Knap for technical assist-
H. Bryde Andenen e t at.
14
ance. The study was supported by The Foundation
of P. Carl Petersen, and by grants from ‘Engineer
Holger Rabitz and Spouse Doris May, Born Philips
Memorial Fund’, The Danish Research and
Development Programme for Food Technology
1990-1994 and from the Danish Medical Research
Council (no. 12-9537-3).
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