title: A stereologic study of the plantar fat pad in young and aged rats.
abstract: Plantar fat pad (PFP) is a tissue structure that absorbs the initial impact of walking and running and ultimately bears body weight at standing. This study was designed to quantify the histomorphological changes of the PFP in aged rats. The most medial PFP was dissected from the hind feet of young rats (4 months old, n = 6) and aged rats (24 months old, n = 6). Histological structure and cellular senescence of PFP were analyzed stereologically and histomorphometrically. Immunohistochemistry of matrix metalloproteinase 9 (MMP9) was also performed on PFP tissue sections. Compared with young rats, the thickness of epidermis, dermis and septa of the PFP were significantly reduced in the aged rats. The total volume of adipose tissue in the PFP of aged rats was only about 65% of that in the young rats. The microvascular density and the number of fat pad units (FPU), a cluster of adipocytes enclosed by elastin septa, in the PFP were unchanged in the aged rats. In the aged rats, the number of adipocytes per FPU was reduced but the number of simple adipocyte clusters, without surrounding septa, was increased. The shift of the types of adipocyte clusters in the aged PFP was accompanied by degradation of elastin fibers and increased expression of MMP9. In conclusion, the PFP, particularly the elastic septa, degenerates significantly in aged rats and this may contribute to the pathology of PFP-related diseases.
authors.affiliation: Orthobiologic Laboratory, Medstar Union Memorial Hospital, Baltimore, MD, USA.
authors.forename: Jeremy
authors.initials: J
authors.lastname: Molligan
authors.forename: Lew
authors.initials: L
authors.lastname: Schon
authors.forename: Zijun
authors.initials: Z
authors.lastname: Zhang
mesh_terms: D017667:Adipocytes / Q000166:cytology; D000273:Adipose Tissue / Q000033:anatomy & histology*; D000375:Aging / Q000502:physiology*; D000818:Animals; D005528:Foot / Q000033:anatomy & histology*; D007150:Immunohistochemistry; D008297:Male; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism; D051381:Rats; D020318:Rats, Long-Evans; D012867:Skin / Q000033:anatomy & histology
chemical_list: D020780:Matrix Metalloproteinase 9
keywords: adipocytes; aging; fat pad; rats; stereology
references.citation: Biochem J. 1993 Jun 15;292 ( Pt 3):873-6
references.pmid: 8318015
references.citation: Arthritis Res Ther. 2008;10(6):R133
references.pmid: 19014513
references.citation: J Foot Ankle Surg. 2010 May-Jun;49(3 Suppl):S1-19
references.pmid: 20439021
references.citation: Foot Ankle Int. 2011 Aug;32(8):802-10
references.pmid: 22049867
references.citation: J Foot Ankle Surg. 2009 Nov-Dec;48(6):648-52
references.pmid: 19857820
references.citation: Ann Rehabil Med. 2011 Aug;35(4):507-13
references.pmid: 22506166
references.citation: Eur J Appl Physiol Occup Physiol. 1996;73(5):404-9
references.pmid: 8803499
references.citation: J Microsc. 1986 Jun;142(Pt 3):259-76
references.pmid: 3735415
references.citation: Proc Natl Acad Sci U S A. 1995 Sep 26;92(20):9363-7
references.pmid: 7568133
references.citation: J Allergy Clin Immunol. 2003 Dec;112(6):1243-5
references.pmid: 14657892
references.citation: Ann N Y Acad Sci. 2007 Nov;1119:40-50
references.pmid: 18056953
references.citation: Biomed Tech (Berl). 1995 Jul-Aug;40(7-8):205-9
references.pmid: 7548685
references.citation: Acta Morphol Neerl Scand. 1984 Dec;22(4):313-23
references.pmid: 6524463
references.citation: Foot Ankle. 1992 Jun;13(5):233-42
references.pmid: 1624186
references.citation: Aging Cell. 2010 Oct;9(5):667-84
references.pmid: 20701600
references.citation: J Anat. 1990 Aug;171:131-8
references.pmid: 2081699
references.citation: J Biomech Eng. 2012 Mar;134(3):031002
references.pmid: 22482682
references.citation: J Appl Biomech. 2008 Nov;24(4):377-81
references.pmid: 19075307
references.citation: J Bone Joint Surg Br. 1994 Jan;76(1):140-2
references.pmid: 8300659
references.citation: Foot Ankle Int. 1999 Oct;20(10):663-8
references.pmid: 10541000
references.citation: Clin Biomech (Bristol, Avon). 2006 Feb;21(2):204-12
references.pmid: 16289518
references.citation: J Biomech Eng. 2009 Sep;131(9):094502
references.pmid: 19725699
references.citation: Laryngoscope. 2005 Mar;115(3):405-11
references.pmid: 15744148
references.citation: Ultrasound Med Biol. 2011 Jul;37(7):1029-38
references.pmid: 21640473
references.citation: Clin Biomech (Bristol, Avon). 2010 Jul;25(6):601-5
references.pmid: 20457479
references.citation: J Orthop Res. 2012 Oct;30(10):1604-10
references.pmid: 22508407
references.citation: Ann Plast Surg. 2009 Apr;62(4):423-9
references.pmid: 19325351
references.citation: Ageing Res Rev. 2011 Jan;10(1):146-52
references.pmid: 20946972
references.citation: J Foot Ankle Surg. 2001 Jan-Feb;40(1):21-7
references.pmid: 11202764
references.citation: Clin Geriatr Med. 1989 Feb;5(1):53-67
references.pmid: 2646002
references.citation: J Rheumatol. 2011 Sep;38(9):1966-72
references.pmid: 21765106
references.citation: Proc Natl Acad Sci U S A. 2010 Oct 19;107(42):18226-31
references.pmid: 20921416
references.citation: J Biomech. 2002 Dec;35(12):1523-31
references.pmid: 12445605
references.citation: J Microsc. 2007 Jan;225(Pt 1):1-9
references.pmid: 17286690
references.citation: Foot Ankle Int. 1995 May;16(5):254-8
references.pmid: 7633580
references.citation: Med Eng Phys. 2012 Nov;34(9):1253-9
references.pmid: 22265099
references.citation: J Biomech. 2012 Jan 10;45(2):364-70
references.pmid: 22079385
references.citation: BMC Cell Biol. 2011 Apr 15;12:16
references.pmid: 21496240
references.citation: J Am Podiatr Med Assoc. 2004 Jan-Feb;94(1):47-52
references.pmid: 14729991
references.citation: Arthritis Rheum. 2008 Mar;58(3):854-63
references.pmid: 18311803
references.citation: Menopause Int. 2007 Jun;13(2):60-4
references.pmid: 17540135
references.citation: Pflugers Arch. 2009 Oct;458(6):1103-14
references.pmid: 19585142
references.citation: J Biomech. 2010 Jun 18;43(9):1754-60
references.pmid: 20207359
references.citation: Osteoarthritis Cartilage. 2009 Jun;17(6):805-12
references.pmid: 19114312
references.citation: Clin Pharmacol Ther. 2013 Jan;93(1):105-16
references.pmid: 23212104