The overall goal of this protocol is to generate a rat model of acquired hypoparathyroidism that is easy to establish, stable in character, and harmless to the thyroid glands. The main advantage of this model is the precise removal of parathyroid glands with the assistance of carbon nanoparticles. We hope the model can help solve a few questions in the field of hypoparathyroidism.
For example, preoperative use of calcium and vitamin D to reduce the risk of post-thyroidectomy hypocalcemia. This method can provide insight into how bone turnover is affected by PTH analogs and how PTH analogs affects the body in long-term use. Those who perform this technique for the first time may find it hard to micro-manipulate under the stereo microscope.
Some practice under stereo microscope may be helpful. To begin, place the anesthetized rat in a supine position and shave the fur of the ventral neck region. After making an incision as described in the manuscript, locate the lobes of the thyroid gland.
Using a 10-microliter syringe equipped with a 30-gauge bevel needle, inject one microliter of the carbon nanoparticle suspension into the mesial portion of the thyroid gland membrane. After five minutes, irrigate the region with saline to clean any extra suspension. Ensure the thyroid glands have turned black and observe the unstained parathyroid gland.
Cut the unstained parathyroid glands using a pair of microsurgery forceps and scissors, and then close the incision with an interrupted horizontal mattress suture. After surgery, place the rats on a thermostatic electric blanket at 37 degrees Celsius to maintain their body temperature. After seven days, draw 10 microliters of blood using the tail vein.
Measure the serum calcium, serum inorganic phosphorus, and serum parathyroid hormone using commercial kits. The parathyroidectomy rats displayed stable hypocalcemia and hyperphosphatemia over the observation period of four weeks. The serum parathyroid hormone was undetected in the parathyroidectomy rats seven days post-operation.
The serum urea and creatinine were comparable between the sham and parathyroidectomy groups after seven days post-operation. Reduced urinary calcium ions and inorganic phosphate levels were observed two weeks post-operation. No significant differences in body weight were observed between the parathyroidectomy and sham groups across 28 days.
The serum C-telopeptide decreased significantly in parathyroidectomy rats. There were no significant differences in the serum osteocalcin levels. However, nanoparticle suspension injection is the most important thing and a successful injection is critical for identification and present removal of the parathyroid glands.
Other methods include fluorescence-guided surgery, diphteria toxin injection of PTHcre-iDTR transgenic mice, and the sterile parathyroidectomy which could help answer questions in the field of hyperthyroidism.
