Rahman K M, Lovich J E, Lam C, Camp M E, Wiley A A, Bartol F F, Bagnell C A
Department of Animal Sciences, Endocrinology and Animal Biosciences Program, Rutgers University, New Brunswick, NJ, USA.
Department of Anatomy, Physiology and Pharmacology, Cellular and Molecular Biosciences Program, Auburn University, Auburn, AL, USA.
Domest Anim Endocrinol. 2014 Jul;48:84-92. doi: 10.1016/j.domaniend.2014.02.006. Epub 2014 Mar 5.
The lactocrine hypothesis suggests a mechanism whereby milk-borne bioactive factors delivered to nursing offspring affect development of neonatal tissues. The objective of this study was to assess whether nursing affects testicular development in neonatal boars as reflected by: (1) Sertoli cell number and proliferation measured by GATA-4 expression and proliferating cell nuclear antigen immunostaining patterns; (2) Leydig cell development and steroidogenic activity as reflected by insulin-like factor 3 (INSL3), and P450 side chain cleavage (scc) enzyme expression; and (3) expression of estrogen receptor-alpha (ESR1), vascular endothelial growth factor (VEGF) A, and relaxin family peptide receptor (RXFP) 1. At birth, boars were randomly assigned (n = 6-7/group) to nurse ad libitum or to be pan fed porcine milk replacer for 48 h. Testes were collected from boars at birth, before nursing and from nursed and replacer-fed boars at 50 h on postnatal day (PND) 2. Sertoli cell proliferating cell nuclear antigen labeling index increased (P < 0.01) from birth to PND 2 in nursed, but not in replacer-fed boars. Sertoli cell number and testicular GATA-4 protein levels increased (P < 0.01) from PND 0 to PND 2 only in nursed boars. Neither age nor nursing affected testicular INSL3, P450scc, ESR1, or VEGFA levels. However, testicular relaxin family peptide receptor 1 (RXFP1) levels increased (P < 0.01) with age and were greater in replacer-fed boars on PND 2. Results suggest that nursing supports neonatal porcine testicular development and provide additional evidence for the importance of lactocrine signaling in pigs.
泌乳内分泌假说提出了一种机制，即通过乳汁传递给哺乳后代的生物活性因子会影响新生组织的发育。本研究的目的是评估哺乳是否会影响新生公猪的睾丸发育，具体通过以下指标来反映：（1）通过GATA-4表达和增殖细胞核抗原免疫染色模式测量支持细胞数量和增殖；（2）胰岛素样因子3（INSL3）和P450侧链裂解酶（scc）表达所反映的睾丸间质细胞发育和类固醇生成活性；（3）雌激素受体α（ESR1）、血管内皮生长因子（VEGF）A和松弛素家族肽受体（RXFP）1的表达。出生时，将公猪随机分组（每组n = 6 - 7头），一组自由哺乳，另一组人工饲喂猪乳代用品，持续48小时。在出生时、哺乳前以及出生后第2天（PND）50小时，分别从自由哺乳和人工饲喂代用品的公猪中采集睾丸。自由哺乳的公猪从出生到PND 2，其支持细胞增殖细胞核抗原标记指数增加（P < 0.01），而人工饲喂代用品的公猪则未增加。仅在自由哺乳的公猪中，从PND 0到PND 2，支持细胞数量和睾丸GATA-4蛋白水平增加（P < 0.01）。年龄和哺乳均未影响睾丸INSL3、P450scc、ESR1或VEGFA水平。然而，睾丸松弛素家族肽受体1（RXFP1）水平随年龄增加（P < 0.01），且在PND 2时，人工饲喂代用品的公猪中该水平更高。结果表明，哺乳有助于新生仔猪睾丸发育，并为泌乳内分泌信号在猪中的重要性提供了额外证据。
