Jellyman J K, Valenzuela O A, Allen V L, Holdstock N B, Fowden A L
Department of Physiology, Development and Neuroscience, University of Cambridge, UK.
Equine Vet J. 2014 Nov;46(6):722-8. doi: 10.1111/evj.12230. Epub 2014 Apr 14.
Pancreatic β cells are responsive to a range of stimuli during early post natal life in healthy pony foals. However, little is known about whether these responses are sex-linked.
To determine pancreatic β cell responses to the insulin secretagogues, glucose, arginine and tolbutamide, in fillies and colts during the first 3 months after birth.
In vivo experiment examining sex differences in pancreatic β cell function in foals.
Female (n = 8) and male (n = 5) pony foals were infused i.v. with glucose (0.5 g/kg bwt 40% dextrose), arginine (100 mg/kg bwt) or tolbutamide (10 or 20 mg/kg bwt) over 5 min, at 48 h intervals, to assess pancreatic β cell function at ages 2 and 12 weeks. Blood samples (4 ml) were taken through a jugular catheter at -30, -15 and 0 min (immediately before) and 5, 15, 30, 45, 60, 90 and 120 min after glucose, arginine and tolbutamide administration for measurements of plasma glucose, α-amino-nitrogen and insulin concentrations.
The maximum increment in plasma insulin concentration in response to glucose was significantly higher in female (395 ± 58 ng/l) than male (172 ± 37 ng/l, P<0.05) pony foals 2 weeks after birth and the area under the insulin curve was significantly greater in females at this age. At 12 weeks, the insulin increment in response to glucose was significantly greater in fillies 45 min post infusion. The β cell responses to arginine and tolbutamide were not sex-linked at either age.
These data show that in ponies, fillies have a greater β cell response to glucose than colts in early post natal life. Since glucose clearance was unaffected by sex, the results suggest that fillies may be less insulin sensitive than colts shortly after birth. Innate sex differences in the secretion and action of insulin in early post natal life may influence tissue development and growth with potentially more long-term metabolic consequences.
在健康小马驹出生后的早期生活中，胰腺β细胞对一系列刺激有反应。然而，对于这些反应是否与性别相关，人们了解甚少。
确定出生后前3个月内，雌性和雄性小马驹的胰腺β细胞对胰岛素促分泌剂、葡萄糖、精氨酸和甲苯磺丁脲的反应。
一项体内实验，研究小马驹胰腺β细胞功能的性别差异。
对8匹雌性和5匹雄性小马驹每隔48小时静脉输注葡萄糖（0.5 g/kg体重的40%葡萄糖）、精氨酸（100 mg/kg体重）或甲苯磺丁脲（10或20 mg/kg体重），持续5分钟，以评估2周龄和12周龄时的胰腺β细胞功能。在输注葡萄糖、精氨酸和甲苯磺丁脲前30分钟、15分钟和0分钟（即将输注前）以及输注后5分钟、15分钟、30分钟、45分钟、60分钟、90分钟和120分钟，通过颈静脉导管采集4毫升血样，用于测量血浆葡萄糖、α-氨基氮和胰岛素浓度。
出生2周后的雌性小马驹（395±58 ng/l）对葡萄糖反应的血浆胰岛素浓度最大增幅显著高于雄性（172±37 ng/l，P<0.05），且该年龄段雌性的胰岛素曲线下面积显著更大。在12周龄时，输注后45分钟，雌性小马驹对葡萄糖的胰岛素增幅显著更大。在两个年龄阶段，β细胞对精氨酸和甲苯磺丁脲的反应均与性别无关。
这些数据表明，在小马驹出生后的早期生活中，雌性对葡萄糖的β细胞反应比雄性更强。由于葡萄糖清除不受性别影响，结果表明出生后不久雌性可能比雄性对胰岛素的敏感性更低。出生后早期胰岛素分泌和作用的先天性性别差异可能会影响组织发育和生长，并可能产生更长期的代谢后果。
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