Evaluation of sympathetic skin response in Parkinson's disease.

There is no clear definition on the role of sympathetic skin response (SSR) in the evaluation of patients with Parkinson's disease (PD). We recorded the SSR of the palms of 64 controls and 46 patients with PD to electrical stimulation of the median nerve at the wrist. We analyzed onset latency and peak-to-peak amplitude. A study of parasympathetic function (R-R interval analysis) was also undertaken. We found that patients with PD had more absent SSRs than controls. The mean amplitude of the SSR was significantly reduced in both lower and upper limbs of PD patients in comparison with control subjects (p<0.001). The onset latency was longer in the lower limbs of these patients in respect to the control group (p<0.003). There was a significant inverse correlation between SSR amplitudes and age, severity and late onset of the disease. There was no association of these parameters with dysautonomic symptoms or R-R interval variation. In conclusion, there is a significant association between altered SSR and PD and an inverse correlation in this group of patients between SSR values and older age, greater severity and later onset of disease. Therefore, the study of SSR may provide valuable information on cholinergic sympathetic function in patients with PD.

Effect of photic stimuli on rat salivary glands. Role of sympathetic nervous system.

Saliva secretion during feeding facilitates chewing, swallowing and other oral functions. Between meals, a "resting saliva" is elicited to allow speaking and contribute to maintain soft and hard tissues health. Chewing is the main stimulus for "stimulated saliva" secretion. Mouth dryness and other less well known stimuli control "resting saliva". In humans the stimulus of the light increases the parotid saliva flow rate. Saliva secretion occurs in response to a reflex. Both motor branches of the autonomous nervous system drive efferent outputs to the salivary glands. Cellular bodies of sympathetic motor fibers innervating salivary glands are located in the superior cervical ganglia. A multisynaptic pathway couples the superior cervical ganglia to hypothalamic areas related to the control of autonomous and endocrine functions. Projections from suprachiasmatic nuclei involved in circadian rhythms control reach those areas. Salivary glands postsynaptic beta-adrenoceptors control synthesis and secretion of proteins. Postsynaptic alpha 2-adrenoceptors modulate salivary responses mediated by alpha 1 and beta-adrenoceptors. Parotid alpha-amylase circadian rhythm in suckling rats, suggest that the sympathetic nervous system mediates an effect of light on saliva secretion. Analysis of: 1) parotid fine structure, 2) submandibular secretory response to adrenergic agonists, and 3) submandibular 3H-clonidine binding to alpha 2-adrenoceptors, demonstrated that an increase of sympathetic reflex activity occurs in salivary glands of rats chronically exposed to constant light. Similar effects were observed in rats chronically exposed to immobilization stress. Catecholamine biosynthetic enzyme mRNA levels in adrenal glands and superior cervical ganglia suggest that changes induced by light on salivary sympathetic reflex activity are mediated by plasma catecholamines released by adrenal glands. Post and presynaptic alpha 2 adrenoceptors could play an important role in saliva secretion control when light or stress stimuli modify the sympathoadrenal system.