Scaramal J D, Renauld A, Gómez N V, Garrido D, Wanke M M, Márquez A G
Departamento de Medicina, Facultad de Ciencias Veterinarias, Universidad de Buenos Aires.
Medicina (B Aires). 1997;57(2):169-80.
The influence of spontaneous "sex seasons" on blood sugar (BS) and serum insulin levels was studied in bitches with natural diabetes mellitus (DM) and normal controls, in the basal condition and during glucose and insulin tests, was studied. DM increased basal BS, reduced glucose tolerance, distribution space (DS) and clearance from blood, and induced resistance to insulin hypoglycemic action. In normals occurrence of "seasons", inconsistently modified basal BS, increased glucose tolerance and DS; during estrogenic phase (EP), these variables were above those during luteal phase (LP). In diabetics at LP, BS found in lasting condition and during glucose test were higher than in diabetic bitches at EP (respective values at anestrous (A) in between) and glucose DS was smaller. Rate of glucose clearance from blood remained unaffected by "seasons" in both dog groups. Basal serum IRI was not modified by DM or "seasons". In normals, serum IRI response to glucose load was nonsignificant during A and increased during the "seasons"; either insulin DS or the rate of insulin clearance from blood stream remained unchanged under the circumstances, the increase being mediated by insulin secretion. During EP, the increase was particularly intense and mean insulinogenic index (MII) rose. During LP, MII returned to A value, whereby diabetic states might be manifest. Serum IRI profiles during insulin test were not modified by "seasons" in normal bitches; such response in diabetic bitches was intense during A, then decreased (EP) or was later abolished (LP). Either in normal or diabetic bitches, the sensitivity to exogenous insulin hypoglycemic action remained unchanged in spite of "seasons". In diabetic bitches at A, serum IRI after glucose challenge peaked higher than in respective normal controls (insulin clearance and insulin DS were similar): they exhibited relative insulin shortage and resistance to insulin hypoglycemic action partly compensated by promoted insulin secretion. Along with "season", abolished serum IRI response to glucose load in diabetics was observed. During EP, extrapancreatic factors regulating serum IRI concentration and MII did not change in respect to A, whereby abolishment appears mediated by depressed insulin secretion. During LP, insulin antagonism in conjunction with 1) absolute insulin deficiency and 2) intense decrease in MII appears as a powerful factor exposing diabetic bitches to a severe or fatal derangement in diabetic disease.
研究了自然糖尿病（DM）母犬和正常对照母犬在基础状态以及葡萄糖和胰岛素测试期间，自发“发情季节”对血糖（BS）和血清胰岛素水平的影响。糖尿病增加了基础血糖，降低了葡萄糖耐量、分布空间（DS）和血液清除率，并诱导了对胰岛素降糖作用的抵抗。在正常母犬中，“发情季节”的出现不一致地改变了基础血糖，增加了葡萄糖耐量和分布空间；在雌激素期（EP），这些变量高于黄体期（LP）。在糖尿病母犬的黄体期，持续状态和葡萄糖测试期间的血糖高于雌激素期的糖尿病母犬（发情间期（A）的相应值介于两者之间），且葡萄糖分布空间较小。两组犬中，血液中葡萄糖清除率不受“发情季节”影响。基础血清IRI不受糖尿病或“发情季节”影响。在正常母犬中，发情间期对葡萄糖负荷的血清IRI反应不显著，在“发情季节”增加；在此情况下，胰岛素分布空间或胰岛素从血流中的清除率保持不变，增加由胰岛素分泌介导。在雌激素期，增加尤为强烈，平均胰岛素生成指数（MII）升高。在黄体期，MII恢复到发情间期的值，从而可能表现出糖尿病状态。正常母犬胰岛素测试期间的血清IRI曲线不受“发情季节”影响；糖尿病母犬的这种反应在发情间期强烈，然后降低（雌激素期）或随后消失（黄体期）。无论在正常还是糖尿病母犬中，尽管有“发情季节”，对外源胰岛素降糖作用的敏感性保持不变。在发情间期的糖尿病母犬中，葡萄糖激发后的血清IRI峰值高于相应的正常对照（胰岛素清除率和胰岛素分布空间相似）：它们表现出相对胰岛素缺乏和对胰岛素降糖作用的抵抗，部分通过促进胰岛素分泌得到补偿。随着“发情季节”，观察到糖尿病母犬血清IRI对葡萄糖负荷的反应消失。在雌激素期，调节血清IRI浓度和MII的胰腺外因素相对于发情间期没有变化，因此消失似乎是由胰岛素分泌受抑制介导的。在黄体期，胰岛素拮抗作用与1）绝对胰岛素缺乏和2）MII的强烈降低一起，似乎是使糖尿病母犬面临糖尿病严重或致命紊乱的一个重要因素。
