Background:There is evidence that sow heat stress (HS) during gestation affects fetal development with implications for impaired muscle growth. We have previously demonstrated that maternal HS during early to mid-gestation compromised muscle fibre hyperplasia in developing fetal pigs. Thus, we hypothesised these phenotypic changes are associated with a change in expression of genes regulating fetal skeletal muscle development and metabolism. To test this, at d 60 of gestation, RNA sequencing and immunohistochemistry were performed on fetal longissimus dorsi (LD) muscle biopsies collected from pregnant gilts that had experienced either thermoneutral control (CON, 20 ℃, n=7 gilts, 18 LD samples) or controlled HS (cyclic 28 to 33 ℃, n=8 gilts, 23 LD samples) conditions for 3 weeks. Results:A total of 282 genes were differentially expressed between the HS and CON groups in female LD muscles (false discovery rate (FDR)≤0.05), whereas no differentially expressed genes were detected in male LD muscles between the two groups (FDR>0.05). Gestational HS increased the expression of genes associated with transcription corepressor activity, adipogenesis cascades, negative regulation of angiogenesis and pro-inflammatory signalling in female LD muscles. Immunohistochemical analyses revealed a decreased muscle vascularity density in fetuses from HS group for both sexes compared to those from the CON group (P=0.004). Conclusions:These results reveal gilt HS during early to mid-gestation altered gene expression profiles in fetal LD muscles in a sexually dimorphic manner. The molecular responses, including transcription and angiogenesis repressions and enhanced adipogenesis cascades, were exclusively observed in females. However, the associated reductions in muscle vascularity were observed independently of sexes. Collectively this may indicate female fetal pigs are more adaptive to gestational HS in terms of gene expression changes, and/or there may be sexually dimorphic differences with respect to the timing of muscle molecular responses to gestational HS.

Weicheng Zhao;Mark P.Green;Christina D.Marth;Fan Liu;Hieu H.Le;Gordon S.Lynch;Alan W.Bell;Brian J.Leury;Frank R.Dunshea;Jeremy J.Cottrell

School of Agriculture and Food,Faculty of Veterinary and Agricultural Sciences,The University of Melbourne,Parkville,VIC 3010,Australia;School of BioSciences,Faculty of Science,The University of Melbourne,Parkville,VIC 3010,Australia;Melbourne Veterinary School,Faculty of Veterinary and Agricultural Sciences,The University of Melbourne,Werribee,VIC 3030, Australia;Rivalea Australia Pty Ltd,Corowa,NSW 2646,Australia;Centre for Muscle Research,Department of Anatomy and Physiology,The University of Melbourne,Parkville 3010,Australia;Department of Animal Science,Cornell University,Ithaca,NY 14853-4801,USA;Faculty of Biological Sciences,The University of Leeds,Leeds LS29JT,UK

畜牧与生物技术杂志（英文版）

[1]Weicheng Zhao;Mark P.Green;Christina D.Marth;Fan Liu;Hieu H.Le;Gordon S.Lynch;Alan W.Bell;Brian J.Leury;Frank R.Dunshea;Jeremy J.Cottrell-.Gestational heat stress alters skeletal muscle gene expression profiles and vascularity in fetal pigs in a sexually dimorphic manner)[J].畜牧与生物技术杂志（英文版）,2022(06):1785-1798

hypothesised,thermoneutral,corepressor,gilt,repressions

Gestational,heat,stress,alters,skeletal,expression,profiles,vascularity,fetal,pigs,sexually,dimorphic,manner,Background,There,evidence,that,sow,HS,during,affects,development,implications,impaired,growth,We,have,previously,demonstrated,maternal,early,mid,compromised,fibre,hyperplasia,developing,Thus,these,phenotypic,changes,associated,regulating,metabolism,To,test,this,sequencing,immunohistochemistry,were,performed,longissimus,dorsi,LD,biopsies,collected,from,pregnant,gilts,had,experienced,either,CON,samples,controlled,cyclic,conditions,weeks,Results,total,differentially,expressed,between,groups,muscles,false,discovery,FDR,whereas,detected,two,increased,transcription,activity,adipogenesis,cascades,negative,regulation,angiogenesis,inflammatory,signalling,Immunohistochemical,analyses,revealed,decreased,density,fetuses,both,sexes,compared,those,Conclusions,These,results,altered,molecular,responses,including,enhanced,exclusively,observed,females,However,reductions,independently,Collectively,may,indicate,more,adaptive,gestational,terms,there,differences,respect,timing

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