title: Regulation of lipid droplet-associated proteins following growth hormone administration and feed restriction in lactating Holstein cows.
abstract: Lipid metabolism plays a crucial role in the adaptation of dairy cows to periods of energy insufficiency. The objective of the current study was to determine if lipolytic proteins are consistently regulated when energy mobilization is stimulated by different factors. We evaluated 2 models of altered energy balance in mid-lactation Holstein cows, including feed restriction (FR) and administration of bovine growth hormone (GH), by quantifying the abundance and (or) phosphorylation of hormone-sensitive lipase (HSL), perilipin (PLIN), and adipose triglyceride lipase (ATGL). For GH administration, adipose tissue and blood samples were collected 4d before and 3 and 7d after administration of GH (n=20 cows). Similarly, adipose and blood samples were obtained 6d before and 1 and 4d after initiation of FR (n=18 cows). Estimated net energy balance decreased and nonesterified fatty acid concentration increased in both experimental models. Decreased ATGL and PLIN protein abundance was observed with GH administration and FR. Additionally, the abundance of phosphorylated HSLSer565 decreased in both models. Decreased abundance of phosphorylated PLIN was observed with GH administration, but not FR. Decreased ATGL protein abundance appears to be a consistent response to energy insufficiency in lactating cows, as this response was also described with negative energy balance at the onset of lactation. In contrast, the abundance of PLIN protein and phosphorylation of HSL using antibodies targeting serine residue 565 of HSL (HSLSer565) were altered in the current research, but not at the onset of lactation. Our findings demonstrate that lipolysis is altered through the regulation of multiple proteins, and that this regulation differs according to physiological state in lactating cows.
authors.affiliation: Department of Animal Science, Iowa State University, Ames 50011.
authors.forename: M P
authors.initials: MP
authors.lastname: Faylon
authors.affiliation: Department of Animal Science, Iowa State University, Ames 50011.
authors.forename: D E
authors.initials: DE
authors.lastname: Koltes
authors.affiliation: Department of Animal Science, Iowa State University, Ames 50011. Electronic address: moodyd@iastate.edu.
authors.forename: D M
authors.initials: DM
authors.lastname: Spurlock
mesh_terms: D000818:Animals; D002352:Carrier Proteins; D002417:Cattle / Q000097:blood / Q000502:physiology*; D004734:Energy Metabolism / Q000187:drug effects* / Q000502:physiology; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D005508:Food Deprivation / Q000502:physiology*; D013006:Growth Hormone / Q000494:pharmacology*; D007774:Lactation / Q000502:physiology; D066292:Lipid Droplets / Q000502:physiology*; D050356:Lipid Metabolism / Q000502:physiology*; D008066:Lipolysis / Q000502:physiology; D000070778:Perilipin-1; D010750:Phosphoproteins; D010766:Phosphorylation / Q000502:physiology; D002787:Sterol Esterase / Q000235:genetics / Q000378:metabolism
chemical_list: D002352:Carrier Proteins; D005230:Fatty Acids, Nonesterified; D000070778:Perilipin-1; D010750:Phosphoproteins; C073294:growth hormone, bovine; D013006:Growth Hormone; D002787:Sterol Esterase
keywords: adipose triglyceride lipase; energy balance; hormone-sensitive lipase; perilipin