Metabolism and Thyroid Hormone

Part 1

Which rat had the fastest basal metabolic rate (BMR)?

The normal rat had the faster basal metabolic rate, because it was not missing its pituitary gland or its thyroid gland.

Why did the metabolic rates differ between the normal rat and the surgically altered rats? How well did the results compare with your prediction? The normal rat has the highest BMR because it has the glands required to stimulate and regulate the release of thyroid hormones.

If an animal has been thyroidectomized, what hormone(s) would be missing in its blood? Triiodothyronine and thyroxine.

If an animal has been hypophysectomized, what effect would you expect to see in the hormone levels in its body? For the hypophysectomized rat, TSH would be missing due to the missing pituitary gland.

Part 2

What was the effect of thyroxine injections on the normal rat’s BMR? The levels were a little off. The normal rat was hyperthyroidic because the thyroxine increases the metabolic rate but it did not develop a goiter.

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What was the effect of thyroxine injections on the thyroidectomized rat’s BMR? How does the BMR in this case compare with the normal rat’s BMR? Was the dose of thyroxine in the syringe too large, too small, or just right? The BMR increased for the thyroidectomized rat with the thyroxine injections.

The BMR was still a little bit under the normal rat's BMR with thyroxine. The dose was too low.

What was the effect of thyroxine injections on the hypophysectomized rat’s BMR? How does the BMR in this case compare with the normal rat’s BMR? Was the dose of thyroxine in the syringe too large, too small, or just right? The BMR increased for the hypophysectomized rat with the thyroxine injections. The BMR was still a little bit under the normal rat's BMR with thyroxine. The dose was too low

Part 3

What was the effect of thyroid-stimulating hormone (TSH) injections on the normal rat’s BMR? The effect of TSH was to increase the normal rat's BMR

What was the effect of TSH injections on the thyroidectomized rat’s BMR? How does the BMR in this case compare with the normal rat’s BMR? Why was this effect observed? There was no effect on the thyroidectomized rat's BMR with the injection of TSH because there was no thyroid gland to stimulate. What was the effect of TSH injections on the hypophysectomized rat’s BMR? How does the BMR in this case compare with the normal rat’s BMR? Was the dose of TSH in the syringe too large, too small, or just right? The hypophysectomized rat's BMR increased with TSH. The BMR was just below the normal rat's BMR but still lower. The syringe amount was a little too low.

Part 4

What was the effect of propylthiouracil (PTU) injections on the normal rat’s BMR? Why did this rat develop a palpable goiter? The effect of PTU injections on the normal rat was to decrease the BMR. The palpable goiter was due to buildup of the precursors of thyroxine. What was the effect of PTU injections on the thyroidectomized rat’s BMR? How does the BMR in this case compare with the normal rat’s BMR? Why was this effect observed? The effect of PTU injections on the thyroidectomized rat was not visible because there was no thyroid gland to be affected. What was the effect of PTU injections on the hypophysectomized rat’s BMR? How does the BMR in this case compare with the normal rat’s BMR? Why was this effect observed? The effect of PTU injections on the hypophysectomized rat was not visible because the rat is missing the pituitary gland. Activity 2 Plasma Glucose, Insulin, and Diabetes Mellitus

What is a glucose standard curve, and why did you need to obtain one for this experiment? Did you correctly predict how you would measure the amount of plasma glucose in a patient sample using the glucose standard curve? The glucose standard curve correlates the intensity of the color obtained and measured on a spectrophotometer (optical density) to the glucose concentration. Which patient(s) had glucose reading(s) in the diabetic range? Can you say with certainty whether each of these patients has type 1 or type 2 diabetes? Why or why not? Patient 3 and 5 had a fasting plasma glucose in the diabetic range. Its not possible to tell if they have type 1 or type 2 diabetes just from their fasting plasma glucose. 3. Describe the diagnosis for patient 3, who was also pregnant at the time of this assay. This would be described as gestational diabetes which often disappears after the pregnancy. Which patient(s) had normal glucose reading(s)?

Patient 1 and 2 were in normal range.

What are some lifestyle choices these patients with normal plasma glucose readings might recommend to the borderline impaired patients? Limit the ingestion of simple sugars. Choose good carbs such as whole wheat and fiber based carbohydrate choices. Exercise regularly.

Activity 3 Hormone Replacement Therapy

Why were ovariectomized rats used in this experiment? How does the fact that the rats are ovariectomized explain their baseline T scores? The ovaries produce estrogen and estrogen stimulates bone growth. Without estrogen bone growth is impaired and osteoporosis is a common result. What effect did the administration of saline injections have on the control rat? How well did the results compare with your prediction? Saline had no effect. The inclusion of the saline as a negative control is to ensure that saline has no effect. What effect did the administration of estrogen injections have on the estrogen-treated rat? How well did the results compare with your prediction? The estrogen injections did increase the rats vertebral bone density and is indicated by the negative T score.

What effect did the administration of calcitonin injections have on the calcitonin-treated rat? How well did the results compare with your prediction? The calcitonin showed no change in the vertebral bone density. What are some health risks that postmenopausal women must consider when contemplating estrogen hormone replacement therapy? Health risks of estrogen therapy include an increased incidence of uterine cancer, breast cancer, and blood clots. Activity Measuring Cortisol and Adrenocorticotropic Hormone 1 Which patient would most likely be diagnosed with Cushing’s disease? Why? Patient would be diagnosed bc the levels of cortisol and ACTH are both high.

Which two patients have hormone levels characteristic of Cushing’s syndrome? Patients 2 and 5 both have high levels of cortisol and low ACTH. 3 Patient 2 is being treated for rheumatoid arthritis with prednisone. How does this information change the diagnosis? The diagnosis would change to iatrogenic or physician induced Cushings syndrome. 4 Which patient would most likely be diagnosed with Addison’s disease? Why? Patient 4 bc the level of ACTH is high but the level of cortisol is low.