Thesis (PhD)--Stellenbosch University, 2000. / ENGLISH ABSTRACT: Diabetes Mellitus (DM) is synonymous with "B-cell failure". Ligation of the pancreatic
duct distally to its confluence into the bile duct has been shown to induce endocrine
tissue regeneration from a number of probable sources. The cells responsible for
regeneration are supposed to possess either dormant pluripotent stem cell ability and/or
the plasticity to undergo metaplasia to form new and surplus endocrine tissue able to
replace pathologically and/or experimentally compromised pancreas. The sequence of
events (cell lineage) during this process of neogenesis, has been the source of
controversy for quite some time as various studies suggest that the cell lineage differs
from in vivo and in vitro studies, according to experimental model and species of
laboratory animal.
The object of this study was to utilise an established experimental laboratory animal
model to study islet morphological changes, neogenesis and or both in vivo. Further
aims of the study were to determine the extent, sequence and magnitude of pancreatic
duct ligation (PDL) induced endocrine neogenesis/morphogenesis in a laboratory rat
model using occlusive pancreatic duct ligation.
PDL's were performed on six groups of 25 normal adult Sprague-Dawley (SD) rats
(300g+) according to the method of Hultquist and Jonsson (1965). Experimental
animals were sacrificed at 12 hr intervals from day one post-PDL to day 10 and every
24 hrs thereafter to day 14 as described by Wang, Klëppel, Bouwens (1995). Animals
received BrdU (a thymidine marker and cell proliferation indicator) 50mglkg
intraperitoneally as described by Wang et al. (1995), one hour prior to removal of the
pancreas after which it was fixed in Bouin's solution and histologically processed.
Seven consecutive 3-6 urn thick serial sections were sequentially stained with H & E,
insulin (I), glucagon (G), somatostatin (ST), pancreatic polypeptide (PP), neuropeptide
tyrosine (NPY) and peptide tyrosine tyrosine (PYY). Immunolabeling was done
according to the method of Guesdon, Temynck , Avrameas (1979). Double
immunolabeling for BrdU and each pancreatic peptide was performed on the sections
on days 3,5, 7, 9 and 11 as described by Wang et al (1994). Cellular transformation between one and 3Yz days was characterised by simultaneous
total deletion and/or transdifferentiation of the acinar compartment and the appearance
of immunoreactive cells for I (11.53 ±1.5%), G (1.85 ±0.8%), pp (1.50 ±0.09%), and
ST (1.96 ±0.24%). Changes in the endocrine composition in existing islets, occurred
along a pathway that saw PP- and ST-cells invading the islet core, islet mantle glucagon
deletion and random appearance of all endocrine cell types within the inter-islet
interstitium on day 3Yz. Days 4 to 6Yz saw further endocrine expansion while days 7 to
14 were distinguished by islet reconstitution and consolidation. NPY immunoreactivity
appeared on day 4Y2 and persisted intermittently throughout while PVV first appeared
on day 4 and disappeared after day 7Yz.
The results suggest that PDL firstly induced the development of endocrine tissue
distributed haphazardly throughout the space previously occupied by acinar parenchyma.
Secondly, the appearance of insulin is preceded by the appearance of PP, glucagon and
somatostatin by 24-hours. A still to be determined proportion of the ligation induced
endocrine formation appeared to be associated with existing islets, resulting in a number
of very large islets, some of which might have secretory access through the glomerularlike
capillary network known to occupy the islet core. The remainder appeared to form
separate "new" islets, which have a dubious access to the blood stream.
In conclusion, if it is true that the pancreas can regenerate some of its endocrine tissue
then it has potential clinical implication for the stabilising of diabetes mellitus. Ligated
exocrine pancreatic tissue, devoid of its acinar component, has been shown to contain
notable quantities of insulin positive cells. This presents intriguing possibilities as an
alternative for donor tissue, usually obtained from rat foetuses, during foetal rat pancreas
transplantation studies. Pancreas tissue harvested from duct ligated rats could replace
the foetal tissue currently used in the treatment of experimental diabetes mellitus in
laboratory animals in this laboratory. / AFRIKAANSE OPSOMMING: Diabetes Mellitus is sinoniem met B-sel disfunksie. Endokriene regenerasie kan
segmenteel bewerkstellig word deur eksperimentele afbinding van die pankreasbuis
distaal tot sy samesmelting met die gemene galbuis. 'n Verskeidenheid van selle word
vermoedelik by hierdie proses betrek. Dormante stamselle besit die vermoë en/of
plastisiteit om 'n aantal vorms van metaplasie te ondergaan om nuwe en/of oortollige
endokriene weefsel te vorm wat patologiese en/of eksperimenteel gekompromiseerde
weefsel vervang. Die selontwikkelings volgorde wat tydens hierdie proses plaasvind
is al vir 'n geruime tyd die middelpunt van 'n meningsverskil. Sommige studies dui
daarop dat die in vivo selontwikkelingsvolgorde verskil van in vitro, volgens
eksperimentele model en tipe proefdier gebruik.
Die doel van die studie was die gebruik van 'n bestaande eksperimentele laboratorium
proefdier model om pankreas eiland morfologiese verandering en/ofneogenese of beide
in vivo te evalueer. Die oogmerk van die studie was om die omvang en volgorde van
veranderings in die endokriene kompartement (neogenese/morfogenese) te bepaal deur
gebruik te maak van 'n pankreas buis afbindings (PBA) model wat totale afsnyding van
die buis tot gevolg het.
PBA's is uitgevoer op ses groepe van 25 volwasse normale Sprague-Dawley (SD)
laboratorium rotte (±300g) soos beskryf deur Hultquist en Jonsson (1965). Proefdiere
is elke 12 uur geoffer vanaf dag een post-PBA tot dag tien en elke 24 uur daarna tot dag
14 soos beskryf deur Wang, Bouwens, Kloppel (1995) na die toediening van 50 mg/kg
5-Bromo-2-deoksi-uridien intraperitoneaal ('n selprolifererings aanduider) soos beskryf
deur Wang et al. (1995). Die pankreas is werwyder, in Bouin se oplossing gefikseer en
histologies geprosesseer. Sewe openvolgende seriesnitte (3-6 urn) is alternatiewelik
gekleur met H & E, en immunositochemies, soos beskryf deur Guesdon, Terugnek,
Avrameas (1979), vir insulien (I), glukagon (G), somatostatien (ST), pankreatiesepolipeptied
(PP), neuropeptied tirosien (NPY) en peptied tirosien-tirosien (PYY). BrdU
dubbel-immuunkleuring is ingesluit op dae 3,5, 7, 9 en 11 soos beskryf deur Wang et
al. (1994). Sellulêre transformasie tussen dae een en 3~ dae is gekenmerk deur gelyktydige en
totale uitwissing en/ofmetaplasie van die asinêre kompartement en die verskyning van
selle immunorektiefvir I(11.53 ±1.5%), G (1.85 ±0.8%), PP (1.50 ±0.09%), ST (1.96
±0.24%). Metaplasie was verantwoordelik vir merkbare veranderings in bestaande
endokriene weefsel langs In transformasie weg waar eiland insulien kemselle vervang
is deur PP- en ST-selle, glukagon buitelaag uitwissing en die toevallige verskyning van
alle endokriene seltipes in the inter-eiland interstitium teen dag 3Y2. Dae 4Y2deur 6~
is gekenmerk deur verdere endokrinetoename terwyl dag 7 deur 14 gekenmerk is deur
eiland hersamestelling en konsolidering. NPY immunoreaktiwiteit was vanaf dag 4~,
met afwisseling, te bespeur terwyl PVV slegs tussen dae 4 en 7 In verskyning gemaak
het.
. Die resultate suggereer eerstens, PBA induseer die ontwikkeling van oortollige
endokriene weefsel op In lukrake wyse versprei deur die ruimte voorheen deur asinêre
parenchiem beset. Tweedens, dat die verskyning van insulien deur dié van PP,
glukagon en somatostatien met minstens 24-uur voorafgegaan is. Die verhouding, van
nuutgevormde endokriene weefsel wat met bestaande eilande assosieer om In aantal baie
groot eilande te vorm, moet nog vasgestel word. Sulke strukture mag moontlik
afskeidings toegang hê tot die bloedstroom, deur die glomerulusagtige kapillêre netwerk,
in die eilandkern teenwoordig terwyl die oorblywende nuutgevormde endokrine weefsel
"nuwe" apparte eilande vorm wat wel of gladnie toegang tot die bloedstroom mag hê nie.
As gevolgtrekking, indien dit waar is dat volwasse pankreas eilandweefsel wel
regenerasie kan ondergaan, dan het dit kliniese implikasie vir die stabilisering van
diabetes mellitus. Weefsel verkry uit PBA bevat geen asinêre weefsel nie maar wel
merkbare hoeveelhede endokriene weefsel, veral insulin positief. Dit bied dan
interessante alternatiewe as skenker weefsel by fetal rot pankreas oorplantings. PBA
en/of die oorplanting van pankreasbuis afgebinde weefsel, na in vitro weefsel kultuur,
bied moontlikhede vir die behandeling van diabetes mellitus.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/51573 |
| Date | 03 1900 |
| Creators | Page, Benedict J. (Benedict John) |
| Contributors | Du Toit, Don F., Wolfe-coote, Sonia A., Stellenbosch University. Faculty of Medicine & Health Science. Dept. of Biomedical Sciences. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
| Format | 253 p. : ill. |
| Rights | Stellenbosch University |
Page generated in 0.0034 seconds