Breathing impairments, such as an alteration in breathing
pattern, dyspnoea, and sleep apnoea, are common health deficits
recognised in Parkinson’s disease (PD). The mechanism that
underlies these disturbances, however, remains unclear. We
investigated the effect of the unilateral damage to the rat
nigrostriatal pathway on the central ventilatory response to
hypercapnia, evoked by administering 6-hydroxydopamine
(6-OHDA) into the right medial forebrain bundle (MFB). The
respiratory experiments were carried out in conscious animals in
the plethysmography chamber. The ventilatory parameters were
studied in normocapnic and hyperoxic hypercapnia before and
14 days after the neurotoxin injection. Lesion with the 6-OHDA
produced an increased tidal volume during normoxia. The
magnified response of tidal volume and a decrease of breathing
frequency to hypercapnia were observed in comparison to the
pre-lesion and sham controls. Changes in both respiratory
parameters resulted in an increase of minute ventilation of the
response to CO2 by 28 % in comparison to the pre-lesion state
at 60 s. Our results demonstrate that rats with implemented
unilateral PD model presented an altered respiratory pattern
most often during a ventilatory response to hypercapnia.
Preserved noradrenaline and specific changes in dopamine and
serotonin characteristic for this model could be responsible for
the pattern of breathing observed during hypercapnia.
The present review brings the survey of the most frequently used behavioural tests in experimental models of Parkinson's disease (PD). Although there is no spontaneous occurrence of parkinsonism in animals, several experimental animal models of PD have been developed to achieve the same clinical features in animals. The techniques employing neurotoxins in lesioning the nigrostriatal dopaminergic (DA) system have a large selectivity and reproducibility. The most frequently used neurotoxins are l-methyl-4-phenyl-l,2,3,6-tetrahydropyridine (MPTP) and 6-hydroxydopamine (6-OHDA). MPTP-lesioned monkeys mimic best the symptomatology of PD in human patients while rats appear to be refractory to MPTP. For that reason, 6-OHDA is used to damage the substantia nigra in a rodent model. Behavioural tests of animals with nigrostriatal lesion represent valuable non- invasive methods for assessing the influence of damaged DA system on locomotor activity. The most frequently used experimental model of PD is the drug-evoked rotation in 6-OHDA unilaterally lesioned rats. This model produces well-defined and stable behavioural deficits. The rotation test is a useful parameter for evaluating imbalances of dopamine in both striata of the hemi-parkinsonian rat model. T-maze, treadmill running test or sensorimotor tests are used to evaluate spontaneous locomotor activity of lesioned animals. Skilled motor tasks measure the influence of dopamine-depleting lesions on complex motor acts. Transplantation of DA tissue into the striatum offers a new approach to the treatment of PD. Experimental models and behavioural tests are used to evaluate the extent of graft-induced recovery of MPTP- or 6-OHDA-lesioned animals. Different results obtained after the use of different tests reflect the level of graft integration into the host circuitry.
Parkinson's disease (PD), which is the second most common
neurodegenerative disorder after Alzheimer's disease, is firstly
defined after James Parkinson's report. It carries motor
symptoms such as resting tremor, bradykinesia and rigidity of
skeletal muscle and freezing of gait. Furthermore, non-motor
symptoms such as cognitive and behavioral problems, besides
sensory impairments are seen in the patients. However, they
may also suffer from sleep disorders or autonomic dysfunction.
Although there are some medications in order to symptomatic
management, but unfortunately, scientist could not have found
exact approaches to cure this disease. Hence, producing a model
which can express the most pathophysiologic and behavioral
aspects of the disease is a desire. In this paper, we aimed to
describe the different models of Parkinson's disease in brief.
Parkinson's disease (PD) is most commonly manifested by the
presence of motor symptoms. However, non-motor symptoms
occur several years before the onset of motor symptoms
themselves. Hallmarks of dysfunction of the respiratory system are
still outside the main focus of interest, whether by clinicians or
scientists, despite their indisputable contribution to the morbidity
and mortality of patients suffering from PD. In addition, many of
the respiratory symptoms are already present in the early stages
of the disease and efforts to utilize these parameters in the early
diagnosis of PD are now intensifying. Mechanisms that lead to the
development and progression of respiratory symptoms are only
partially understood. This review focuses mainly on the
comparison of respiratory problems observed in clinical studies
with available findings obtained from experimental animal models.
It also explains pathological changes observed in non-neuronal
tissues in subjects with PD.