Davidson B D, Gonzales E T, Mast G L, Laporta J
Department of Animal and Dairy Sciences, University of Wisconsin-Madison, Madison, WI 53706.
JDS Commun. 2023 Aug 19;5(1):83-88. doi: 10.3168/jdsc.2023-0400. eCollection 2024 Jan.
Homeostasis and thermoregulation are influenced by the interplay of hair coat and skin characteristics. Our previous work indicated that hair and skin adaptations, triggered by in utero heat stress, affect thermoregulation in postnatal life. Herein, we investigate multigenerational carry-over effects of late-gestation heat stress on hair and skin characteristics beyond the first generation. Pregnant Holstein dams (F, grand-dams) were heat stressed (HT, shade, n = 41) or provided active cooling (CL, shade, fans, and water soakers, n = 41) for the last 56 d of gestation during summer (temperature-humidity index ≥68). The first generation of heifers (F daughters) who were in utero heat stressed (HT, n = 36) or not (CL, n = 37) were born and raised as a cohort from birth to first calving. Thirty second-generation heifers (F, granddaughters), born to HT (HT, n = 12) and CL (CL, n = 18), were raised as a cohort from birth to 70 d of age. Hair samples and skin biopsies from HT and CL were collected on postnatal d 70 (n = 6/group). Hair samples were subdivided into topcoat and undercoat, and skin tissue was fixed for ~18 h in 10% formalin, dehydrated, paraffin-embedded, sectioned, and stained with hematoxylin and eosin to visualize morphology. Variables analyzed included hair length and diameter; stratum corneum cross-sectional area and thickness; epidermis thickness; sweat gland depth, number, cross-sectional area, and average size; and sebaceous gland number, cross-sectional area, and average size. Measurements were performed using the ImageJ software and analyzed using PROC MIXED in SAS (SAS Institute Inc.). Hair length and diameter tended to be shorter and thicker in HT, compared with CL. The HT skin had smaller stratum corneum cross-sectional area and tended to a thinner epidermis. to CL, HT skin had more but smaller sebaceous glands, whereas no differences in sweat glands were observed. In summary, we report phenotypic alterations in hair and skin characteristics of granddaughters. Whether these adaptations grant improved postnatal thermoregulatory ability for the granddaughters remains to be investigated.
体内平衡和体温调节受毛发覆盖和皮肤特征相互作用的影响。我们之前的研究表明，子宫内热应激引发的毛发和皮肤适应性变化会影响出生后的体温调节。在此，我们研究妊娠后期热应激对第一代之后毛发和皮肤特征的多代延续效应。在夏季（温度 - 湿度指数≥68），对怀孕的荷斯坦奶牛（F，即祖母代）在妊娠的最后56天进行热应激处理（HT，置于阴凉处，n = 41）或提供主动降温（CL，置于阴凉处，配备风扇和喷水器，n = 41）。第一代小母牛（F代女儿）在子宫内经历过热应激（HT，n = 36）或未经历过热应激（CL，n = 37），从出生到首次产犊作为一个群体饲养。30头第二代小母牛（F代孙女），由经历过热应激（HT，n = 12）和未经历过热应激（CL，n = 18）的母牛所生，从出生到70日龄作为一个群体饲养。在出生后第70天收集HT组和CL组的毛发样本和皮肤活检组织（每组n = 6）。毛发样本分为外层毛和底层毛，皮肤组织在10%福尔马林中固定约18小时，脱水，石蜡包埋，切片，并用苏木精和伊红染色以观察形态。分析的变量包括毛发长度和直径；角质层横截面积和厚度；表皮厚度；汗腺深度、数量、横截面积和平均大小；以及皮脂腺数量、横截面积和平均大小。使用ImageJ软件进行测量，并在SAS（SAS Institute Inc.）中使用PROC MIXED进行分析。与CL组相比，HT组的毛发长度和直径往往更短、更粗。HT组皮肤的角质层横截面积更小且表皮往往更薄。与CL组相比，HT组皮肤的皮脂腺更多但更小，而汗腺未观察到差异。总之，我们报告了孙女代毛发和皮肤特征的表型改变。这些适应性变化是否能提高孙女代出生后的体温调节能力仍有待研究。
