Changes in activity and structure of jaw muscles in Parkinson's disease model rats

Abstract

Parkinson's disease (PD), a major neurological disease, is characterised by a marked loss of dopaminergic neurons in the substantia nigra. Patients with PD frequently show chewing and swallowing dysfunctions, but little is known about the characteristics of their stomatognathic functions. The purpose of this study was to evaluate the influence of PD on jaw muscle fibre and functions. PD model rats were made by means of the injection of 6-hydroxydopamine (6-OHDA) into the striatum of 8-week-old Sprague-Dawley male rats. Five weeks after the injection, a radio-telemetric device was implanted to record muscle activity continuously from the superficial masseter and anterior belly of digastric muscles. Muscle activity was recorded for 3 days and was evaluated by the total duration of muscle activity per day (duty time). After recording the muscle activities, jaw muscles were isolated for immunohistochemical and PCR analyses. In PD model rats, the following findings of the digastrics muscles verify that compared to the control group: (i) the higher duty time exceeding 5% of the peak activity level, (ii) the higher expression of the mRNA of myosin heavy chain type I, and (iii) the tendency for fast to slow fibre-type transition. With respect to the masseter muscle, there were no significant differences in all analyses. In conclusion, PD leads to the changes in the jaw behaviours, resulting in a PD-specific chewing and swallowing dysfunctions.

Protective Effects of Clenbuterol against Dexamethasone-Induced Masseter Muscle Atrophy and Myosin Heavy Chain Transition

“…Chronic administration of CB induces slow-to-fast MHC isoform transition [ 3 – 5 ] and chronic administration of DEX induces fast-to-slow MHC isoform transition in skeletal muscle [ 6 ]. However, the effect of CB on DEX-induced fast-to-slow MHC isoform transition in the masseter muscle has not been examined.…”

“…β 2 -agonists and glucocorticoids exert opposite effects, i.e., β 2 -agonists promote skeletal muscle hypertrophy and are used as anabolic drugs to increase skeletal muscle weight, whereas glucocorticoids induce myopathy, characterized by muscle weakness, atrophy, and fatigue [ 1 , 2 ]. Furthermore, β 2 -agonists induce slow-to-fast myosin heavy chain (MHC) isoform transition [ 3 – 5 ], while glucocorticoids induce fast-to-slow MHC isoform transition [ 6 ]. Glucocorticoids, such as dexamethasone (DEX) are potent immunosuppressants and anti-inflammatory agents, and are widely used to treat various clinical conditions, including asthma and autoimmune diseases.…”

Effects of the masticatory demand on the rat mandibular development

“…To examine the functional regime of a muscle, its contraction pattern has to be evaluated for at least one complete day, hence incorporating the complete range of functional demands . Radio telemetry enables muscle activity recording in freely moving animals, which ensures normal daily behaviour .…”

Spinocerebellar ataxia: Functional analysis of the stomatognathic system

“…Among the numerous forms of ataxias, spinocerebellar ataxia is defined as a disease that progressively affects the spinocerebellar region with initial clinical manifestations of impaired balance and motor coordination (5,6). The clinical picture is very variable and can include dysmetria, dysdiadochokinesia, and tremors in the appendicular skeleton, signs of pyramidal diseases, cognitive dysfunction, epilepsy, peripheral neuropathies, dementias, parkinsonian syndrome, dystonia, and involuntary movements (7,8).…”

“…Individuals with neurological disorders often have dysfunctions related to swallowing and chewing, but little is known, with scientific evidence, what happened with stomatognathic functions (6).…”