Maribel Castañeda Hernandez
BIO 435.003
Professor Connaughton
Lab 4 Endocrine System
Abstract
The glands of the endocrine system secrete different types of hormones that regulate
metabolism, growth and development, tissue function, and reproduction, among other things.
Many experimental methods can be used to study the functions of the endocrine system. Usually,
experiments examining the effects of hormones are long-term; therefore, we used the PhysioEx
computer software to simulate the experiments using rats. In this lab, we examined three
processes controlled by the endocrine system: (1) metabolism, (2) blood glucose levels, and (3)
hormone replacement therapy. In activity 1, we performed four experiments on three rats (a
normal rat, a thyroidectomized rat, and a hypophysectomized rat). We injected each rat with
thyroxine, TSH, and propylthiouracil to test its effects on the rats’ metabolism. Table 1 shows
the normal baseline of all three rats. Tables 2-4 show the effects of the different hormones on the
rats’ metabolism. Results showed that the thyroidectomized and the hypophysectomized rats had
a lower metabolic rate than the normal rat. In the normal rat, thyroxine and TSH increased the
metabolic rate while the propylthiouracil decreased it. In the thyroidectomized rat, the TSH and
the propylthiouracil decreased the metabolic rate while the thyroxine increased the rate. In the
hypophysectomized rat, both thyroxine and TSH increased the metabolic rate while the
propylthiouracil decreased it. In activity 2, we generated a glucose standard curve to determine
the presence of diabetes in blood samples of five patients. Table 6 shows our results: blood
sample from patient 1 does not show the presence of diabetes (glucose level < 110 mg/dl), blood
sample from patient 2 indicates impairment (glucose level between 110 and 126 mg/dl), and
blood samples from patients 3-5 show the presence of diabetes (glucose level > 126 mg/dl). In
activity 3, we administered estrogen and calcitonin injections to ovariectomized rats that have
osteoporosis (indicated by T score of -2.61) to determine the best replacement hormone therapy.
Our results in Table 7 show that estrogen was the better therapy because the T score of the
estrogen-injected rat (T score of -1.72) was closer to the normal T score (+1) than that of the
calcitonin-injected rat (T score of -2.32). From our results, we concluded that regulating the
amount and type of hormones secreted to a target is important, because a certain amount of a
hormone can have different effects on different individuals. Regulation becomes important when
determining the presence of endocrinological diseases.
Table 1: Normal baseline of metabolic rats
Weight (kg)
ml O2 used in 1
minute
ml O2 used per
hour
Metabolic rate
Palpitation results
Normal rat
0.25
7.2
Thyroidectomized rat
0.244
6.4
Hypophysectomized rat
0.244
6.2
432
384
372
1728
No mass
1573.8
No mass
1524.6
No mass
Table 1 shows the normal metabolic rates for each rat. The thyroidectomized rat and the
hypophysectomized rat had a lower metabolic rate than the normal rat.
Table 2: Effects of thyroxine on metabolic rats
Weight (kg)
ml O2 used in 1
minute
ml O2 used per
hour
Metabolic rate
Palpitation results
Normal rat
0.25
8.4
Thyroidectomized rat
0.244
7.9
Hypophysectomized rat
0.244
7.8
504
474
468
2016
No mass
1943
No mass
1918
No mas
Table 2 shows the metabolic rates for each rat after being injected with thyroxine. The
thyroidectomized rat and the hypophysectomized rat had a lower metabolic rate than the normal
rat. Overall, the metabolic rate for all three rats increased.
Table 3: Effects of TSH on metabolic rats
Weight (kg)
ml O2 used in 1
minute
ml O2 used per
hour
Metabolic rate
Palpitation results
Normal rat
0.25
8
Thyroidectomized rat
0.244
6.3
Hypophysectomized rat
0.244
7.8
480
378
468
1920
Mass
1549
No mass
1918
Mass
Table 3 shows the metabolic rates for each rat after being injected with TSH. The
thyroidectomized rat had a lower metabolic rate than the normal rat and the hypophysectomized
rat.
Table 4: Effects of propylthiouracil on metabolic rats
Weight (kg)
ml O2 used in 1
minute
ml O2 used per
hour
Metabolic rate
Palpitation results
Normal rat
0.25
6.4
Thyroidectomized rat
0.244
6.2
Hypophysectomized rat
0.244
6.3
384
372
378
1536
Mass
1525
No mass
1549
No mass
Table 4 shows the metabolic rates for each rat after being injected with propylthiouracil. Overall,
the metabolic rate for all three rats is about the same. Both the normal rat and the
thyroidectomized rat had a lower metabolic rate than the normal baseline. The
hypophysectomized rat had a slightly higher metabolic rate than its normal baseline.
Table 5: Glucose standard curve results
Tube
1
2
3
4
5
Optical density
0.3
0.5
0.6
0.8
1.0
Glucose (mg/dl)
30
60
90
120
150
Table 5 shows the baseline results of the generated glucose standard curve. According to this
graph, glucose levels below 110 mg/dl are considered normal. Glucose levels between 110 and
126 mg/dl show impairment of insulin-mediated glucose uptake by the cells. And glucose levels
above 126 mg/dl show the presence of diabetes.
Table 6: Fasting plasma glucose results
Sample
1
2
3
4
5
Optical density
0.73
0.79
0.89
0.83
0.96
Glucose (mg/dl)
104
115
132
123
144
Table 6 shows the results of the fasting plasma glucose results. Blood sample from patient 1 does
not show the presence of diabetes because the glucose level is below 110 mg/dl. Blood sample
from patient 2 indicates impairment because the glucose level is between 110 and 126 mg/dl.
Blood samples from patients 3-5 show the presence of diabetes because their glucose levels are
above 126 mg/dl.
Table 7: Hormone replacement therapy results
Rat
Control
Estrogen-injected
Calcitonin-injected
T score
-2.81
-1.72
-2.32
Table 7 shows the T scores of the rats after estrogen and calcitonin injections. T scores of +1 to 0.99 are interpreted as normal. T scores of -1.0 to -2.49 are interpreted as osteopenia. T scores
above -2.5 are interpreted as showing osteoporosis. The T score of the estrogen-injected rat was
closer to the normal T score than that of the calcitonin-injected rat.