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Journal of Korean Neurosurgical Society 1973;2(2): 23-36.
Effects of Total Hypophys Ectomy on the Blood Sugar and Pancreas in the Dog.
Young Hi Cho, Young Il Kim, Bo Sung Sim
1Department of Neurosurgery, College of Medicine, Seoul National University, Seoul, Korea.
2Department of Pathology, College of Medicine, Seoul National University, Seoul, Korea.
Early attempts at determining the effects of experimental ablation of the hypophysis in the mammal resulted ambiguously, for the animals usually died from attendant injury to the brain or form infection, or , if they survived, some of the effects observed often were due to injury to the adjacent regions of the brain during the operation. In 1912, Aschner performed removal of the pituitary body by a transbuccal transsphenoidal route in the dog. Smith in 1927 and 1930 reported two methods of hypophysectomy in the rat; the first one was temporal approach, in this method he exposed the pituitary and destroyed with chromic acid injection; the second one was parapharyngeal route. In 1963, Falconi and Rossi described transauricular hypophysectomy in the rat and mice. It is well known that in studying the effects of hypophysectomy removal of the pituitary must be essentially complete without injury to the adjacent regions of the brain, especially in the hypothalamus. The present study was undertaken to device a method of total hypophysectomy and observe the effects on pancreatic structure and carbohydrate metabolism. In this study twenty adult mongrel dogs, weighting from 7 to 10 kg, were used. Twelve of them were male and eight were female. Operative procedure: Under pentobarbital sodium, 30 mg/kg body weight, intravenous anesthesia the dog was placed on the operating table in prone position, and a tube was inserted in the mouth to displace the mandibular angle anterodownwardly. A vertical incision from the midline to just behind the mandibular angle was made, the temporal muscles were also incised vertically and retracted to expose the temporal bone. Following wide craniectomy down to the base of middle cranial fossa and careful opening the dura, temporal lobe was elevated with about 1cm wide brain retractor at the tip of the middle cranial fossa. Since this approach was deep and narrow, a brilliant illumination was thrown from head lamp at neat the center of the binocular magnifier. As the third cranial nerve and intracranial portion of the internal carotid artery were exposed, arachnoid membrane was torn and aspirated cerebrospinal fluid slowly to obtain wider exposure, then elevated posterior communicating artery to expose the pituitary body and stalk. The stalk was clipped and sectioned then pituitary body was removed in a piece or sucked out under direct vision, and the would was closed in layers. In all experimental dogs, pre- and postoperative fasting blood sugar was measured, and the brain and pancreas were removed and fixed in 10 % neutral formalin solution following intracarotid artery infusion of 10% neutral formalin. The removed brain was examined and the pancreas was stained with hematoxylin-eosin, Maldonado, and Toluidine blue sating methods. The following results were obtained: 1. The average preoperative fasting venous blood sugar was 98.5+/-5.4mg% in 20 mongrel dogs. 2. In five hypophysectomized dogs, their preoperative average blood sugar was 99.2+/-5.2mg% and their postoperative blood sugar was decreased in the rage from 13.0 to 35.4mg% during the period from 56 to 77 days. 3. In ten dogs who received daily intramuscular injection of 2mg dexamethasone following hypophyseetomy, their average venous blood sugar was 99.5+/-6.12mg%, and their postoperative blood sugar was decreased in the range from 9.7 to 30.5mg%. 4. In five normal dogs, the number of cells per islet varied from 14 to 96 and the average number was 45, and the average ratio of alpha, beta to delta cells was 14.2 : 79.4 : 6.4; in hypophysectomized group the average number per islet was 53 and their ratio was 19.5 : 75.1: 5.4; in the group which received dexamethasone for a week following hypophysectomy, the average number per islet was 53 and the average ratio was 14.6 : 80.5: 4.9, and in the group which received dexamethasone for two weeks, the average number per islet was 37 and the ratio was 15.2 : 80.2 : 4.5. 5. The acini in the hypophysectomized dogs were rather atrophic and illustrated mild intracytoplasmic vacuolization, and the Langerhans islet demonstrated exhausted pattern with small and degranulated beta cells. However, the Langerhans islets of hypophysectomized dogs with dexamethasone administration showed regranulated beta cells in one dog. 6. In pancreas of hypophysectomized dogs increased number of mast cells along the interstitial tissue, periductal region, and peripancreatic fat tissue were observed. There were also one or two mast cells in the islet mainly along the capsule of islets. 7. In pancreas of hypophysectomized dog with dexamethasone administration a few mast cells were observed along the lobular margin and just beneath the capsule of the islets.
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