Govoni N, Galeati G, Castellani G, Tamanini C
Dipartimento di Morfofisiologia Veterinaria e Produzioni Animali, University of Bologna, Ozzano Emilia (BO), Italy.
Horm Metab Res. 2005 Mar;37(3):152-8. doi: 10.1055/s-2005-861300.
This study's aim was to examine whether fasting and refeeding would influence leptin levels in both plasma and follicular fluid from prepubertal gilts, and whether insulin affects leptin levels in fasting gilts. In experiment 1, four gilts were fasted for 72 h and then refed. Blood samples were withdrawn during normoalimentation, at the end of fasting, and for 4 h after refeeding. All samples were assayed for leptin; alternate samples were assayed for insulin, glucose and non-esterified fatty acids (NEFA). Fasting caused a decrease in leptin, glucose and insulin levels in plasma, while NEFA concentrations increased. In experiment 2, four gilts were given insulin as a bolus (0.2 IU/kg body weight) after 68 h of fasting. Blood samples were collected every 15 min around insulin administration and were assayed for leptin, insulin and glucose. This experiment shows that insulin administration increases leptin levels during fasting. In experiment 3, gilts were ovariectomized during normal alimentation (n=4), after 48 h of fasting (n=4), and after 48 h of realimentation following 48 h of fasting (n=4). Leptin levels in both plasma and follicular fluid collected after 48 h of fasting were significantly lower than those observed during normoalimentation or refeeding. In conclusion, a transient increase in insulin during fasting is effective in restoring leptin concentrations; in addition, leptin levels in follicular fluid parallel those in plasma.
本研究的目的是检验禁食和再喂养是否会影响青春期前小母猪血浆和卵泡液中的瘦素水平，以及胰岛素是否会影响禁食小母猪的瘦素水平。在实验1中，4头小母猪禁食72小时，然后再喂养。在正常进食期间、禁食结束时以及再喂养后4小时采集血样。所有样本均检测瘦素；交替样本检测胰岛素、葡萄糖和非酯化脂肪酸（NEFA）。禁食导致血浆中瘦素、葡萄糖和胰岛素水平下降，而NEFA浓度升高。在实验2中，4头小母猪在禁食68小时后给予胰岛素推注（0.2 IU/kg体重）。在注射胰岛素前后每隔15分钟采集血样，检测瘦素、胰岛素和葡萄糖。该实验表明，在禁食期间注射胰岛素会增加瘦素水平。在实验3中，小母猪在正常进食期间（n = 4）、禁食48小时后（n = 4）以及禁食48小时后再喂养48小时后（n = 4）进行卵巢切除。禁食48小时后采集的血浆和卵泡液中的瘦素水平显著低于正常进食或再喂养期间观察到的水平。总之，禁食期间胰岛素的短暂增加可有效恢复瘦素浓度；此外，卵泡液中的瘦素水平与血浆中的瘦素水平平行。
