Insulin sensitivity in the hereditary hypopituitary dwarf mouse


Mirand, E.A.; Osborn, C.M.

Proceedings of the Society for Experimental Biology and Medicine 82(4): 746-748

1953


Since the hereditary hypopituitary dwarf mouse (subline, Syracuse) is deficient in anterior-pituitary and adrenocortical secretions, it was of interest to test insulin effects on this naturally occurring form of hypopituitarism. Under the exptl. conditions employed in these studies, findings may be summarized as follows: (a) the insulin-hypersensitive dwarf mouse can tolerate only 3% of the dose (2 units of insulinAg. of mouse) that produces comparable symptoms in normal mice; higher dosages cause severe hypo-glycemia followed by death; and (b) ACTH, adrenocortical extract, cortisone, and growth hormone act as anti-insulin agents as shown by their ability to increase blood-glucose levels and to reduce hypoglycemic convulsions; desoxycorticosterone acetate and testosterone propionate exhibit no anti-insulin action.

Insulin
Sensitivity
in
the
Hereditary
Hypopituitary
Dwarf
Mouse.*
(20234)
E.
A.
MIRANnt
AND
C.
M.
OSBORN.t
(Introduced
by
Robert
Gaunt.)
From
Syracuse
University,
Syracuse,
N.
Y.,
and
the
Roswell
Park
Memorial
Institute,
Buffalo,
N.
Y.
746
Snell
(1)
described
in
a
strain
of
mice
an
hereditary
dwarfism
which
behaved
as
a
true
Mendelian
recessive.
Since
then
many
in-
vestigations
have
been
carried
out
on
the
dwarf
which
have
shown
interesting
morpho-
logical
and
metabolic
anomalies(2,3).
Russell
(4)
reported
that
hypophysectomized
or
ad-
renalectomized
animals
exhibit
a
greatly
in-
creased
sensitivity
to
the
hypoglycemic
effect
of
insulin
as
compared
to
normal
intact
ani-
mals.
Since
the
hereditary
dwarf
is
deficient
in
anterior-pituitary
and
adrenocortical
secre-
tions,
it
was
of
interest
to
test
insulin
effects
on
this
naturally
occurring
form.
Materials
and
methods.
The
animals
used
in
this
study
were
hereditary
hypopitui'tary
dwarf
mice
of
the
Bar
Harbor
strain
(Subline,
Syracuse)
;
for
controls
and
comparative
pur-
poses,
normal
mice
of
the
same
strain
were
utilized.
All,
dwarfs
used
were
9
to
12
months
old,
ranging
in
weight
between
9
and
14
g.
Normal
mice
between
35
and
42
days
old
were
used
as
controls
because
their
weights
at
this
time
were
similar
to
those
of
the
dwarfs;
moreover,
at
this
age
the
normals
are
de-
velopmentally
similar
to
the
dwarfs
at
9
to
12
months.
The
animals
were
fed
Purina
Laboratory
Chow
and
water
ad
lib.
The
temperature
of
the
animal
room
was
carefully
maintained
at
75cF.
Insulin
(Illetin-Lilly)
was
administered
subcutaneously.
Results.
Insulin
sensitivity.
The
dwarfs
are
remarkably
more
sensitive
to
insulin
than
normal
mice,
for
it
takes
only
3%
of
the
dose
*
We
are
indebted
to
Dr.
Irby
Bunding
of
Armour
and
Co.
for
growth
hormone
and
cortisone
as
well
as
to
Dr.
Kenneth
Wade
Thompson,
Medical
Re-
search,
Organon
Inc.,
for
donation
of
desoxycorti-
costerone
acetate.
This
investigation
was
supported
in
part
by
a
grant
from
The
Committee
on
Research
in
Endocrinology,
National
Research
Council.
4
Present
address:
Roswell
Park
Memorial
Insti-
tute.
Buffalo,
N.
V.
Present
address:
University
of
Buffalo,
Buffalo,
N.
V.
of
insulin
given
to
normal
mice
(2
units
per
kilo)
to
cause
a
similar
convulsive
effect.
For
instance,
a
single
dose
of
0.06
unit
of
insulin
injected
after
the
24th
hour
of
fasting
is
suffi-
cient
to
cause
in
1
hour
'a
marked
decrease
of
45%
in
the
blood
sugar
level.
The
same
dos-
age
of
insulin
causes
a
slight
but
significant
drop
in
the
blood
sugar
of
normal
mice
(Table
I).
When
dwarfs
are
fasted
for
18
hours,
al-
lowed
food
for
6
hours,
and
then
injected
im-
mediately
with
0.06
unit
of
insulin
per
kilo,
the
blood
sugar
level
drops
23%
in
an
hour,
or
about
half
as
much
as
was
observed
above
following
a
24-hour
fast.
In
contrast,
normal
mice
under
similar
experimental
conditions
of
dosage
and
fasting
exhibit
a
decrease
of
9%
(Table
I).
Further
evidence
of
this
marked
insulin
sensitivity
of
the
dwarf
is
provided
by
the
observations
that
higher
insulin
dosages
of
0.125,
0.250,
and
0.500
unit
of
insulin
per
kilo
cause
hypoglycemic
coma
and
death
in
the
dwarfs
but
produce
no
observable
symp-
toms
such
as
hypoglycemic
cramps
in
the
nor-
mal
controls.
When
after
24
hours
of
fasting,
adrenalectomized
mice
of
normal
size
are
given
0.5
unit
of
insulin
per
kilo,
cramps
and
hypoglycemia
result
in
1
hour;
but
the
ani-
mals
do
not
succumb.
If
the
dosage
is
raised
to
2
units
per
kilo,
the
adrenalectomized
ani-
mal
enters
a
hypoglycemic
coma
which
is
fol-
lowed
by
death.
Anti-insulin
tests.
In
Table
II
the
effects
of
various
hormones
acting
as
anti-insulin
agents
are
indicated.
Adrenocorticotrophin,
cortisone,
and
adrenocortical
extract
all
ex-
hibit
a
marked
capacity
to
prevent
convul-
sions.
Cortisone
exerts
the
most
marked
anti-
insulin
response
in
both
normal
and
dwarf
mice.
In
normal
intact
animals
cortisone,
ACTH,
and
adrenocortical
extract
counteract
the
effects
of
insulin
to
such
an
extent
that
5,
4.
and
3
times
the
dose
of
insulin
respectively
are
necessary
to
produce
approximately
the
same
percentage
of
convulsions
that
occurs
in
nonprotected
normal
controls
receiving
2
units
of
insulin
per
kilo.
If
normal
mice
are
adrenal-
INSULIN
SENSITIVITY
IN
HYPOPITUITARY
MOUSE
747
TABLE
I.
Effect
of
0.06
Unit
of
Insulin
per
Silo
on
Blood
Sugars
in
Fasted
Dwarf
(dd)
and
Normal
(N)
Mice.
No.
Mean
blood
sugar,
mg
%
±
S.E.,*
at
hr
fasted
Treatment
animals
24t
25
26
28
32
40
45
Insulin
(.06
ml)
10
96+2.1
53+1.8
72+2.2
75±3.0
89±0.9
94-1-1.0
90+1.3
Idem
11
128+3.2
114+2.0
117+1.0
127±1.7
124±1.3
119±1.2
121+2.8
Data
in
lower
half
of
table
similar
to
above
except
that
animals
were
fasted
18
hr,
fed
between
18th
and
24th
hr,
and
fasted
again
after
24th
hr.
90±2.4
82+1.8
142+1.9
144±3.0
130±0.9
121±2.6
112+1.2
*
S.E.
stand.
error.
t
Insulin
inj.
subeut.
TABLE
II.
Anti-Insulin
Tests
in
Normal
Intact
and
Adrenalectomized
Mice
and
Intact
Dwarfs
Fasted
24
Hr.
Treatment
Amt
inj.
Insulin
dose/kilo
mouse
Total
No.
animals
Convulsions,
Intact
normal
mice
Controls
2
39
90
ACTH
.5
nig
9
14
14
8
10
80
Cortisone
"
2
18
0
10
10
70
ACE
.7
ml
2
22
14
6
10
90
DCA
.2
mg
2
19
84
2.0
2
10
100
Testosterone
propionate
2.5
2
21
100
Adrenalectomized
normal
mice*
Controls
.5
9
100
ACTH
.5
mg
.5
8
88
2.0
5
70
Cortisone
.2
.5
10
0
2.0
5
80
ACE
.7
ml
.5
10
10
2.0
5
100
Intact
dwarf
mice
Controls
.06
12
100
ACTH
.5
mg
.06
6
17
.25
5
84)
Cortisone
.2
"
.06
10
10
.30
5
64)
ACE
.7
nil
.06
12
17
.25
5
80
DCA
.2
mg
.06
12
100
2.0
"
.06
12
100
Testosterone
propionate
2.5
.06
12
100
*
Adrenalectomized
animals
maintained
on
daily
subeut.
inj.
of
0.1
mg
of
DCA
in
0.1
ml
of
peanut
oil
and
0.9%
sodium
chloride
in
drinking
water.
dd
N
dd
N
Insulin
(.06
ml)
6
146+4.1
113+1.1
Idem
6
150+3.8
137+2.0
ectomized
and
primed
with
cortisone
and
ACE,
2
units
per
kilo
instead
of
0.5
unit
per
kilo
are
required
to
cause
convulsions.
Dwarf
mice
receiving
ACTH,
cortisone,
and
ACE
convulse
with
4,
5,
and
4
times
the
dose
of
insulin
respectively
in
contrast
to
nontreated
control
dwarfs
receiving
0.06
unit
of
insulin
per
kilo.
The
results
of
these
experiments
(Table
II)
also
serve
to
emphasize
the
ineffectiveness
of
DCA
as
an
anti-insulin
agent
in
both
normal
and
dwarf
mice,
since
dosages
from
.2
to
2
748
INSULIN
SENSITIVITY
IN
HYPOPITUITARY
MOUSE
mg
proved
incapable
of
preventing
convul-
sions.
This
observation
is
of
interest
since
it
has
been
generally
considered
by
Wang
and
Verzar
(5)
that
DCA
is
capable
of
affecting
carbohydrate
metabolism.
With
a
tenfold
in-
crease
in
the
dosage,
it
appears
that
sufficient
DCA
absorption
should
occur
to
reveal
any
possible
anti-insulin
effect.
Nevertheless,
none
was
obtained.
In
all
experiments
reported
here,
testoster-
one
propionate
exhibited
no
anti-insulin
effect
(Table
II).
Discussion.
Although
this
study
has
shown
that
the
hypopituitary
dwarf
mouse
is
ex-
tremely
sensitive
to
insulin
as
compared
with
controls,
the
mechanism
'to
explain
the
in-
creased
sensitivity
of
the
dwarf
is
not
defi-
nitely
understood.
On
theoretical
grounds,
any
or
all
of
the
following
factors
may
be
re-
sponsible
for
this
phenomenon:
a)
A
decreased
rate
of
inactivation
of
insulin
by
the
blood
and
tissues.
b)
Inadequate
counterregulatory
responses
(i.e.,
glycogenolysis
and
gluconeo-
genesis)
to
hypoglycemia
by
the
liver.
c)
Hypophyseal
and
adrenocortical
deficiencies,
perhaps
rendering
the
dwarf
incapable
(es-
pecially
under
the
stress
of
fasting)
of
pro-
ducing
an
anti-insulin
factor
or
factors
such
as
ACTH
and
adrenocortical
hormones
oxy-
genated
at
C-11
and
17.
Identification
of
insulin-antagonistic
fac-
tors
is
of
interest.
The
present
study
shows
that
ACTH,
cortisone,
and
ACE
are
antago-
nistic
to
the
blood-sugar
lowering
action
of
insulin,
i.e.,
they
increase
the
tolerance
of
the
dwarf
to
a
given
dose
of
insulin.
Preliminary
experiments
(unpublished
data)
have
shown
that
growth
hormone
is
also
anti-insulin.
In-
sulin
sensitivity
and
anti-insulin
action
under
these
conditions
perhaps
are
associated
with
a
pituitary
deficiency
per
se
as
well
as
with
the
deficiencies
of
the
pituitary-adrenal
axis.
The
above
findings
are
consistent
with
what
is
known
in
other
experimental
and
clinical
situations(6-8).
Summary.
Under
the
experimental
condi-
tions
employed
in
these
studies,
findings
may
be
summarized
as
follows:
a)
The
insulin-
hypersensitive
hereditary
hypopituitary
dwarf
mouse
can
tolerate
only
3%
of
the
dose
of
insulin
that
produces
comparable
symptoms
in
normal
mice
(2
units
of
insulin/kg
of
mouse).
Higher
dosages
cause
severe
hypoglycemia
fol-
lowed
by
death.
b)
ACTH,
adrenocortical
extract
(ACE),
and
cortisone
act
as
anti-in-
sulin
agents
as
shown
by
their
ability
to
in-
crease
blood-glucose
levels
and
to
reduce
hypo-
glycemic
convulsions.
Desoxycorticosterone
acetate
and
testosterone
propionate
exhibit
no
anti-insulin
action.
c)
Factors
that
may
be
responsible
for
the
hypersensitivity
to
insulin
are
discussed.
1.
Snell,
G.
D.,
Proc.
Acad.
Sci.,
1929,
v15,
733.
2.
Mirand,
E.
A.,
and
Osborn,
•C.
M.,
Anat.
Rec.,
1951,
v109,
379.
3.
,
PROC.
SOC.
EXP.
BIOL.
AND
MED.,
1952,
v81,
706.
4.
Russell,
J.
A.,
Am.
J.
Physiol.,
1938,
v121,
755.
5.
Wang,
F.
C.,
and
Verzar,
F.,
Am.
J.
Physiol.,
1949,
v159,
263.
6.
Jensen,
H.,
and
Grattan,
J.
F.,
Am.
J.
Physiol.,
1940,
v128,
270.
7.
Grattan,
J.
F.,
Jensen,
H.,
and
Ingle,
D.
J.,
Am.
J.
Physiol.,
1941,
v134,
8.
8.
De
Bodo,
R.
C.,
Kurtz,
M.,
Ancowitz,
A.,
and
Kiang,
S.
P.,
PROC.
Soc.
EXP.
BIOL.
AND
MED.,
1950,
v74,
524.
Received
March
2,
1953.
P.S.E.B.M.,
1953,
v82.