4 research outputs found
Ultrastructural response of arcuate nucleus neurons to fasting in aged rats
The arcuate nucleus of the hypothalamus (ARH) is involved in the control of
energy homeostasis. Leptin - an adipocyte derived hormone - is known to
act on the hypothalamic nuclei and thus to control body weight by food intake
reduction. Oxidative stress is believed to be implicated in leptin signalling. However,
its relevance for leptin-induced signal transduction within ARH remains
unclear. The goal of the study was to investigate the effect of fasting on morphological
alterations of the neuronal endoplasmic reticulum/Golgi network as
well as on the expression of leptin receptors in the arcuate nucleus of aged
rats. Male Wistar rats, aged 24 months, were fasted for 96 hours. The control
animals were fed ad libitum. Membranous whorls in the ARH neurons were
visualized using the electron microscopy technique. Leptin receptors in the
membranes of ARH neurons were determined immunohistochemically (IHC),
and soluble leptin receptors in the plasma as well as plasma isoprostanes were
quantified immunochemically (ELISA). An intense formation of membranous
whorls was observed, directly associated with the cisternae of the rough endoplasmic
reticulum, as well as lamellar bodies. Interestingly, the whorls were
often localized near a well-developed Golgi complex. Moreover, some Golgi
complexes displayed an early stage of whorl formation. Groups of residual
lipofuscin granules were found in the immediate proximity of the whorls. An
increased immunoreactivity with neuronal leptin receptors suggests that hypersensitive
neurons may still effectively respond to the fasting serum levels of
leptin, mediating ultrastructural transformation of ARH neurons during short-term fasting. Having observed a significant accumulation of lipofuscin granules
and a marked increase of total 8-isoprostane serum level in the fasting rats, we
hypothesize that signal transduction within the neurons of ARH is dependent
on oxidative stress phenomena
Morphological alterations in the jejunal mucosa of aged rats and the possible protective role of green tea
Introduction. Gastrointestinal disorders become more prevalent with ageing. This study is aimed to describe morphological changes that occur in the jejunal mucosa of male albino rats as a result of ageing and the protecÂtive effect of green tea (GT) extract.
Material and methods. The experiment was performed on sixty rats: thirty young-adult (6-month old, body mass 200–220 g) and thirty old (24-month-old, body mass 220–260 g) animals. Each group was further divided into two subgroups (n = 15 each): control rats and GT-treated rats that received 1.5 mL (300 mg/kg/day) of GT extract for 14 weeks by oral gavage. Sections of the jejunum were stained with hematoxylin and eosin, periodic acid Schiff, toluidine blue and Mallory trichrome methods. The presence of proliferating cell nuclear antigen (PCNA)- and CD68-positive cells was evaluated by immunohistochemical staining. Ultrathin sections were prepared and examined by a transmission electron microscope (TEM).
Results. Jejunal sections of the old control rats showed distortion of submucosa and attenuated muscularis externa with decreased height of intestinal villi. The villi also showed partial loss of acidophilic brush border with wide spaces between enterocytes. Swollen, short, blunt or broad villi with abundant mononuclear cell infiltration of lamina propria and congested blood vessels were evident both by light and electron microscopy. The number of PCNA- and CD68-positive cells in jejunal mucosa of old rats was higher than in young rats. The activity of glutathione peroxidase (GPX) and total antioxidant capacity (TAC) in the mucosa of old control rats were lower, whereas malondialdehyde (MDA) levels were higher in the jejunal homogenates of old rats as compared to young control rats. Administration of GT extract protected the jejunal mucosa from age-related changes by restoring its histological structure. The treatment of old rats with GT extract significantly decreased MDA levels in the jejunum and increased TAC and GPX activity.
Conclusions. The age-related changes of the morphology of rat jejunum could be ameliorated by prolonged supplementation of the green tea extract