cle containing 10 ethanol, 10 Tween-80 before being administered to rats on three occasions at
doses of 25, 25 and 50 mgkg with 18 and 6 h between successive treatments. The effectiveness
of the capsaicin treatment in destroying non- myelinated afferent fibers was confirmed by the
failure to exhibit corneal reflex in response to 1 NH
4
OH. The lorglumide was purchased from Sigma and was dissolved in 0.9 saline before
being administered to the rats.
2
.
6
. Statistical analysis Data are expressed as mean 9 S.E.M. An a of
0.05 was accepted as the level of statistical signifi- cance. ANOVA was used with Bonferroni’s cor-
rection for multiple comparisons to compare repeat measure studies.
3. Results
3
.
1
. Experiment
1
, acute dose-response to oral simmondsin
Fig. 1 shows the food intake of rats that ate a diet containing simmondsin at one of five levels
beginning at the onset of the dark cycle. Begin- ning at 4 h, but more evident at 6 and 24 h, there
was a significant dose-related suppression of food intake at 24 h. At 24 h, the highest dose 2.00
had decreased food intake by \ 60.
3
.
2
. Experiment
2
, acute dose-response to intraperitoneal simmondsin
When simmondsin was administered intraperi- toneally Fig. 2, a dose-dependent reduction in
food intake was evident at 0.5 h and became striking at 1, 2, 4 and 6 h. By 24 h, it was still
present, but the highest dose depressed food in- take by B 50 compared to a \ 50 reduction
at 1, 2, 4 and 6 h. The continuing effect at 24 h suggests a relatively long biological half-life for
this molecule.
3
.
3
. Experiment
3
, CCK antagonist lorglumide and food intake after simmondsin
Fig. 3 shows the effect of administering 600 mgkg of simmondsin alone or with lorglumide
600 mgkg. This dose blocks the anorectic response to CCK data not shown. Simmondsin sup-
pressed food intake by \ 50 at 0.5, 1 and 2 h,
Fig. 1. Effect of simmondsin on food intake. Simmondsin was added to the diet in the concentrations shown in the legend.
Fresh diet with simmondsin as a first exposure was given to rats at the onset of dark. Food intake was measured at 1, 2, 4,
6 and 24 h after beginning to eat the simmondsin-adulterated diet. Data are expressed as mean 9 S.E.M. P B 0.05 com-
pared to control group.
Fig. 2. Effect of intraperitoneal simmondsin on food intake. Overnight-fasted rats received intraperitoneal injections of
simmondsin at one of four doses or vehicle. There was a clear-cut dose-related reduction in food intake at all time
points. Data are expressed as mean 9 S.E.M. P B 0.05 com- pared to control group.
Fig. 3. Effect of i.p. lorglumide on intake of food after i.p. simmondsin. Overnight-fasted animals were given injections of
vehicle, simmondsin 600 mgkg or simmondsin with lorglu- mide 600 mgkg. Simmondsin reduced food intake which was
not affected by simultaneous administration of lorglumide, a drug that blocks CCK
A
receptors. Data are expressed as mean 9 S.E.M. P B 0.05 compared to control group.
and then after 4 h to see if there was any temporal effect. The suppression of food intake by sim-
mondsin was unaffected by lorglumide data not shown.
3
.
4
. Experiment
4
, conditioned taste a6ersion Animals were conditioned to associate sim-
mondsin or LiCl treatment with saccharine solu- tion. When they were subsequently given a choice
of saccharine or water drinking solution Fig. 4, the liquid intake of the vehicle-treated animals
was 64 9 12 saccharine, the liquid intake for the simmondsin pre-treated group was 45 9 8 sac-
charine, P \ 0.1, whereas the lithium-treated rats showed a marked suppression of saccharine
intake 7 9 1, P B 0.005 versus other intakes. Thus, simmondsin does not appear to be aversive
in this context.
3
.
5
. Experiment
5
, chronic feeding study with simmondsin
Fig. 5 shows the mean body weight of the control group, the simmondsin group 0.5 in
diet and the pair-fed group. Simmondsin pre- vented weight gain and subsequently produced
weight loss in these animals. Control rats were significantly heavier than the simmondsin-treated
rats by the third day of treatment. Six of the ten rats in the simmondsin group died, but none of
the rats in the other group.
Mean food intake of the simmondsin-treated animals was reduced on Day 1 to : 15 9 0.6 g
per day and fell slowly to levels of 13 9 2 g per day until Day 40. Thereafter, food intake fell
below 10 g per day as animals began to die. Rapid weight loss of individual rats began on Day 10
and between Day 35 and Day 46 for the other rats. The time of death of rats is shown by the
arrows in Fig. 5. Deaths began as early as 38 days after treatment began in animals fed simmondsin.
The experiment was terminated early at Day 52 because of the high death rate. At autopsy, the
blood from the simmondsin-treated animals ap- peared watery and did not clot during the entire
2-h period of autopsies. Fig. 6 shows the liver and kidney weight from the three groups. Liver and
Fig. 4. Effect of simmondsin on taste aversion to saccharine. Simmondsin, 600 mgkg, lithium chloride 81 mgkg and
vehicle were paired with 0.15 saccharine drinking solution. After a 2-day rest, animals were again given saccharine or
water to drink. The percent of saccharine intake was signifi- cantly suppressed in the animals previously treated with
lithium chloride but not the animals previously treated with simmondsin. Values represent means 9 S.E.M. P B 0.01
compared to control group.
but somewhat less at the other times. At no time did lorglumide affect the suppression of food
intake by simmondsin. In a second experiment, lorglumide and simmondsin were given in two
injections, one at the beginning of the experiment
Fig. 5. Mean body weights of animals chronically treated with simmondsin. The animals fed the control diet gained weight progressively throughout the experiment. The animals eating the 0.5 simmondsin-adulterated diet had a decrease in body weight,
as did the animals pair-fed, to those eating the simmondsin diet. The arrows indicate time of death of individual rats two on Day 46. Data are expressed as mean 9 S.E.M.
Fig. 6. Liver and kidney weight from the chronic simmondsin experiment. The liver and kidney of the pair-fed animals were lighter than control, but, relative to the pair-fed group, the simmondsin-treated animals had larger kidneys and liver. Data are expressed
as mean 9 S.E.M. P B 0.05 compared to control group.
Fig. 7. Metabolic rates and respiratory quotients of rats treated with simmondsin. Values represent means 9 S.E.M.
periartiolar sheaths
and accumulation
of hemosiderin-laden macrophages in the red pulp.
Only the simmondsin fed animals had these le- sions. Other tissues did not contain significant
changes except kidneys, which showed occasional dilated tubules filled with an amorphous, homoge-
neous, eosinophilic material protein cast.
Energy expenditure in both the simmondsin and pair-fed group was lower Fig. 7B : 8
kcal100 g bw than in the control group 12 – 14 kcal100 g bw, but did not augment during the
night in simmondsin and pair-fed rats Fig. 7A. The respiratory quotient was higher at night
0.95 – 0.98 in all three groups than in the day 0.83 – 0.90, but did not differ between treatment
groups Fig. 7B.
3
.
6
. Experiment
6
, chronic dose-ranging study with and without capsaicin treatment
Fig. 8 shows the body weight of animals treated with simmondsin. Included in this figure are two
control groups, one for the simmondsin-fed ani- mals and a capsaicin-treated control for the sim-
mondsin-treated capsaicin-treated animals. Once again, the animals fed a diet with 0.5 sim-
mondsin had a reduced food intake and lower body weight than the other groups. The lowest
doses of simmondsin 0.015 and 0.05 and the capsaicin control groups were slightly heavier
than the control group. Simmondsin 0.15 had no effect on body weight, but it blocked the
unexpected increase that was observed in rats treated with capsaicin. However, none of these
effects reached statistical significance with the ex- ception of the highest dose of simmondsin 0.5,
which significantly reduced both body weight. Likewise, there were no significant effects on food
intake at any doses other than the 0.5 sim- mondsin, which significantly reduced feeding
data not shown. At autopsy, the animals treated with the highest dose of simmondsin had smaller
livers and light epididymal and retroperitoneal fat pads than the ad-lib controls data not shown.
The hematocrit in the animals treated with 0.15 and 0.5 simmondsin was below the normal
range for the control rats in this experiment Fig. 9.
kidney weights of the pair-fed animals were sig- nificantly lower than in the control group. Rela-
tive to the pair-fed controls, the liver and kidney of the group fed 0.5 simmondsin were signifi-
cantly heavier P B 0.05, although still signifi- cantly smaller than the ad-lib controls.
Several lesions were noted histologically, pri- marily in the bone marrow and spleen. Possible
lesions were also noted in some of the lymph nodes. Three of the simmondsin animals had
moderate to severe lesions in the bone marrow. There was marked hypocellularity or atrophy of
all bone marrow hematopoietic cell lines erythro- cytic cells, granulocytic cells and megakaryocytes
with replacement by adipose tissue. Animals with bone marrow lesions also had mild thinning of the
bone traveculae, with loss of some traveculae and thinning of cortical bone as well. The splenic
lesions consisted of atrophy of the lymphocytic
4. Discussion
