Intravaginal instillation of gonadotropin-releasing hormone analogues with an absorption enhancer induced a surge of luteinizing hormone in lactating dairy cows
Intravaginal instillation of gonadotropin-releasing hormone analogues with an absorption enhancer induced a surge of luteinizing hormone in lactating dairy cows
复制标题
DOI：
10.3168/jds.2016-12513
复制
发表时间：
2017-09-01
影响因子：
3.5
通讯作者：
Giordano, J. O.
中科院分区：
文献类型：
--
作者：
Wijma, R.;Stangaferro, M. L.;Giordano, J. O.
我们的目的是评估泌乳奶牛阴道内（IVG）滴注GnRH类似物后的循环LH浓度。在2个实验中，泌乳荷斯坦奶牛（实验1：n = 32;实验2：n = 47）在2种PGF（2 α）中的第一种后48 h接受实验处理，间隔12 h和在修改的Ovsynch方案（GnRH在-7 d，PGF（2 α），在-24 h，PGF（2 α），在-56 h，GnRH在0 h）后7 d给予处理。在实验1中，将奶牛按胎次分层，并随机分配接受以下治疗：2 mL盐水IVG（SAL，n = 6），100 μ g戈那瑞林（Gon）i.m.（G100-IM，n = 5）和100（G100，n = 7）、500（G500，n = 8）或1，000 μ g Gon IVG（G1000，n = 7）。在实验2中，处理为SAL（n = 8）、G100-IM（n = 8）、G1000（n = 7）、1，000 μ g Gon +10%柠檬酸（CA）IVG（G1000 CA，n = 8）、80 μ g布舍瑞林IVG（B80，n = 8）和80 μ g布舍瑞林+10% CA IVG（B80 CA，n = 8）。在两项实验中，从-15分钟到4小时每15分钟采集一次血液，从治疗后4小时到6小时每30分钟采集一次血液。使用SAS的PROC MIXED（9.4版，SAS Institute Inc.，卡里，北卡罗来纳州）。使用SAS的PROC FREQ，采用Fisher精确检验评价LH激增的奶牛比例。在这两个实验中，LH浓度受治疗，时间和治疗时间相互作用的影响。在实验1中，G100-IM处理的LH AUC和最大LH浓度最大，G1000处理的AUC和最大LH浓度大于SAL和G500处理。观察到LH激增的奶牛比例为100%，接受Gon i.m.的奶牛为0%。和IVG。在实验2中，G100-IM、G1000 CA和B8 OCA治疗的AUC和最大LH浓度高于其他IVG治疗。LH激增的奶牛比例因处理而异（SAL = 0%，G100-IM = 100%，G1000 = 14%，G1000 CA = 88%，B80 = 13%和B8 OCA = 100%）。对于LH激增的处理，G100-IM处理的LH达到最大浓度的时间最短，G1000 CA处理居中，B8 OCA处理的奶牛最长。总之，单次IVG滴注后，Gon（高达1，000 μ g）通过完整阴道上皮的吸收不足以引起正常水平的LH激增。相反，IVG滴注1，000 μ g Gon和80 μ g布舍瑞林并加入柠檬酸作为吸收促进剂，导致LH激增，其特征与i.m.注射100 μ g Gon。
Our objectives were to evaluate circulating LH concentrations after intravaginal (IVG) instillation of GnRH analogs in lactating dairy cows. In 2 experiments, lactating Holstein cows (experiment 1: n = 32; experiment 2: n = 47) received the experimental treatments 48 h after the first of 2 PGF(2 alpha), treatments given 12 h apart and 7 d after a modified Ovsynch protocol (GnRH at -7 d, PGF(2 alpha), at -24 h, PGF(2 alpha), at -56 h, GnRH at 0 h). In experiment 1, cows were stratified by parity and randomly allocated to receive the following treatments: 2 mL of saline IVG (SAL, n = 6), 100 mu g of gonadorelin (Gon) i.m. (G100-IM, n = 5), and 100 (G100, n = 7), 500 (G500, n = 8), or 1,000 mu g of Gon IVG (G1000, n = 7). In experiment 2, treatments were SAL (n = 8), G100-IM (n = 8), G1000 (n = 7), 1,000 mu g of Gon plus 10% citric acid (CA) IVG (G1000CA, n = 8), 80 mu g of buserelin IVG (B80, n = 8), and 80 mu g of buserelin plus 10% CA IVG (B80CA, n = 8). In both experiments, blood was collected every 15 min from -15 min to 4 h, and every 30 min from 4 to 6 h after treatment. Data for area under the curve (AUC), mean LH concentrations, and time to maximum LH concentration were analyzed by ANOVA with (mean LH only) or without repeated measures using PROC MIXED of SAS (version 9.4, SAS Institute Inc., Cary, NC). The proportion of cows with a surge of LH was evaluated with Fisher's exact test using PROC FREQ of SAS. In both experiments, LH concentrations were affected by treatment, time, and the treatment by time interaction. In experiment 1, the AUC for LH and maximum LH concentration were greatest for the G100-IM treatment and were greater for the G1000 than for the SAL and G500 treatments. The proportion of cows with an observed surge of LH was 100 and 0% for cows that received Gon i.m. and IVG, respectively. In experiment 2, the AUC and maximum LH concentrations were greater for the G100-IM, G1000CA, and B8OCA treatments than for the other IVG treatments. The proportion of cows with a surge of LH differed by treatment (SAL = 0%, G100-IM = 100%, G1000 = 14%, G1000CA = 88%, B80 = 13%, and B8OCA = 100%). For the treatments with a surge of LH, time to maximum concentration of LH was the shortest for the G100-IM treatment, intermediate for the G1000CA treatment, and the longest for cows in the B8OCA treatment. In conclusion, Gon (up to 1,000 mu g) absorption through intact vaginal epithelium after a single IVG instillation was insufficient to elicit a surge of LH of normal magnitude. Conversely, IVG instillation of 1,000 mu g of Gon and 80 mu g of buserelin with the addition of citric acid as absorption enhancer resulted in a surge of LH of similar characteristics than that induced after i.m. injection of 100 mu g of Gon.