Effect of atropine-induced flow rate depression on the composition of unstimulated human parotid fluid

Impact of a simplified in situ protocol on enamel loss after erosive challenge

This study investigated the effect of the period of use and location of intraoral appliances on enamel surface loss. This randomized, single blind in situ study was conducted in 2 crossover phases based on the period of use, in which maxillary and mandibular appliances were simultaneously worn. Bovine enamel blocks (n = 120) were randomly divided among the studied groups by surface hardness. In each phase, fifteen volunteers used one maxillary appliance and two mandibular appliances for 5 days. Erosive challenge was performed 4X/day by immersion in 0.01 M HCL for 2 minutes. In the continuous phase, the intraoral appliances were worn for 20 hours. In the intermittent phase the appliances were worn for 8 hours and 30 minutes. Enamel loss was determined profilometrically. The discomfort of use of the appliances were evaluated in a questionnaire. Data were analyzed by two-way ANOVA/Tukey’s test and chi-square test (p<0.05). The maxillary appliance promoted higher enamel loss compared to the mandibular one (p<0.001). Intermittent use of appliances resulted in similar enamel loss to the continuous one (p = 0.686). All volunteers preferred to use the maxillary appliance in an intermittent regimen. The intermittent use of maxillary appliance is a simplified reliable protocol appropriated for in situ erosion studies in enamel.

Lewy pathology in the submandibular gland of individuals with incidental Lewy body disease and sporadic Parkinson's disease

A retrospective autopsy-based study of the human submandibular gland, one of the three major salivary glands, together with anatomically related peripheral structures (cervical superior ganglion, cervical sympathetic trunk, vagal nerve at the level of the carotid bifurcation), was conducted on a cohort consisting of 33 individuals, including 9 patients with neuropathologically confirmed Parkinson's disease (PD), three individuals with incidental Lewy body disease (iLBD), 2 individuals with neuropathologically confirmed multiple system atrophy (MSA), and 19 controls, using alpha-synuclein immunohistochemistry in 100 mum polyethylene glycol-embedded tissue sections. Lewy pathology (LP) was present in the submandibular glands and cervical superior ganglia in PD (9/9 cases) and iLBD (2/3 cases) but not in MSA or controls. The cervical sympathetic trunk (7/9 PD cases, 2/3 iLBD cases) and peripheral vagal nerves (9/9 PD cases, 2/3 iLBD cases) also displayed LP. The results are discussed within the context of hyposmia as well as autonomic dysfunction in PD (sialorrhea, sialopenia, dysphagia). Potential disease-related changes in salivary volume, contents, and viscosity might make it possible, in combination with other tests, to employ human saliva as a biomarker.

Regulation of salivary gland function by autonomic nerves

Oral homeostasis is dependent upon saliva and its content of proteins. Reflex salivary flow occurs at a low 'resting' rate and for short periods of the day more intense taste or chewing stimuli evoke up to ten fold increases in salivation. The secretion of salivary fluid and proteins is controlled by autonomic nerves. All salivary glands are supplied by cholinergic parasympathetic nerves which release acetylcholine that binds to M3 and (to a lesser extent) M1 muscarinic receptors, evoking the secretion of saliva by acinar cells in the endpieces of the salivary gland ductal tree. Most salivary glands also receive a variable innervation from sympathetic nerves which released noradrenaline from which tends to evoke greater release of stored proteins, mostly from acinar cells but also ductal cells. There is some 'cross-talk' between the calcium and cyclic AMP intracellular pathways coupling autonomic stimulation to secretion and salivary protein secretion is augmented during combined stimulation. Other non-adrenergic, non-cholinergic neuropeptides released from autonomic nerves evoke salivary gland secretion and parasympathetically derived vasointestinal peptide, acting through endothelial cell derived nitric oxide, plays a role in the reflex vasodilatation that accompanies secretion. Neuronal type, calcium-activated, soluble nitric oxide within salivary cells appears to play a role in mediating salivary protein secretion in response to autonomimetics. Fluid secretion by salivary glands involves aquaporin 5 and the extent to which the expression of aquaporin 5 on apical acinar cell membranes is upregulated by cholinomimetics remains uncertain. Extended periods of autonomic denervation, liquid diet feeding (reduced reflex stimulation) or duct ligation cause salivary gland atrophy. The latter two are reversible, demonstrating that glands can regenerate provided that the autonomic innervation remains intact. The mechanisms by which nerves integrate with salivary cells during regeneration or during salivary gland development remain to be elucidated.

Influences of emotion upon parotid secretion in human

Fluid of the parotid gland was collected from seven human subjects during sleep and four subjects during wakefulness. It was continuously weighed during collection on an electronic balance. The weight value was processed on line by a personal computer, and circadian rhythm in connection with the flow rate of saliva was studied. One subject showed no secretion of saliva throughout sleep, but in the other subjects, saliva was secreted, although it was slight. There was no difference between the flow rate in rapid eye movement (REM) sleep and non-REM sleep. Every subject during wakefulness showed a flow rate in a range from a very high value to one almost equal to the value during sleep. The flow rate during wakefulness varied greatly, and there seemed to be no rhythmic pattern to it. With the aid of auditory or visual stimuli etc., the influence of emotional state upon parotid secretion was investigated in 12 subjects. It was found that the flow rate decreased significantly from an intense, passionate state to a relaxed, pleasant state, to a tense or uneasy state and was lowest in a passive, indifferent state, being almost the same as that during sleep. These findings suggest that secretion of parotid saliva depends more on emotional state than circadian rhythm.

An evaluation of microdisks for dental identification

Twenty polyester dental identification microdisks were bonded to the surface of 20 extracted human mandibular molars and placed in 0.9% saline solution for 26 weeks, after which the teeth with bonded microdisks were embedded in bovine muscle tissue and incinerated for 11 minutes. Under the conditions of this study, 2 of the 20 polyester microdisks did not demonstrate deterioration and remained legible after storage in saline. The teeth and bonded microdisks did not appear to be affected by 11 minutes of incineration. A list of ideal characteristics for identification microdisks did proposed.

Salivary changes in solution pH: a source of individual differences in sour taste perception

The role of saliva in sour taste perception was investigated in a series of 4 experiments. In one pair of experiments, solution pH was measured before and after acetic, citric or hydrochloric acid solutions were mixed with saliva either normally in the oral cavity or after saliva was directly added to solutions. The results showed that large increases in solution pH occurred over a wide range of acid concentrations and that the changes in pH were related to individual salivary flow rates; greater increases in solution pH occurred among those individuals with higher flow rates. The other pair of experiments measured taste threshold and suprathreshold responses to different volumes of acids. The results demonstrated that individuals with high salivary flow rates were less sensitive to the taste of acids and that large volumes of acid were more easily perceived. The pattern of findings suggest that saliva-induced changes in solution pH are important in sour taste perception.

Influence of atropine on taste-stimulated parotid secretion

Elemental taste qualities as "sour" and "sweet" showed different stimulatory effects on the parotid secretion when given in concentrations with comparable gustatory intensity. Sweet (fructose 10%) exerted an adrenergic-like activity, sour (citric acid 1%) a more parasympathetic-like influence on parotid secretion. The vagal pathway of the gustatory stimuli was further investigated by the simultaneous infusion of atropine sulfate (17 micrograms/kg per 30 min). Atropine reduced the flow rate during sour and sweet stimulation in the range of 500% and 300%. In 60% of the test persons parotid flow rate could not be totally depressed in any of three 10-min sampling fractions by atropine when a sour stimulus was applied; in these subjects protein and amylase concentration increased significantly. Following fructose stimulation the flow rate was totally depressed in all subjects by atropine in the 20- and 30-min sampling fractions. In the first 10-min fraction protein and amylase concentration were not influenced by atropine. The cholinergic pathway seems to be responsible primarily for the flow rate and has further different modulating influence on the stimulatory effect of the individual taste qualities.

Long-term follow-up of the effect of tympanic neurectomy on sialadenosis and recurrent parotitis

We examined the effect of tympanic neurectomy on the clinical symptoms and secretory function of the parotids in 13 patients with chronic parotitis or sialadenosis for 3 years. Each patient had significantly fewer complaints immediately after the surgery. In quite a few patients the improvement was transient only. Three years after neurectomy 3 of the 10 examined patients were free from complaints and 4 further patients had less severe complaints than before the surgery. Neurectomy was followed by a significant decrease in parotid flow rate and an increase in the sodium concentration of parotid saliva, while potassium concentration showed a slight decrease. Three years after the surgery the flow rate and the sodium concentration were moderately higher than before that. There was a significant, long-lasting change in the amylase activity of parotid saliva; 3 years after neurectomy it attained one-third of the preoperative value. A pharmacological test, carried out 3 years after neurectomy in 2 patients, suggested parasympathetic reinnervation of the parotid.

Effects of pharmacologic reductions in salivary flow on taste thresholds in man

The effects of short-term salivary flow reductions on human taste thresholds were measured. Recognition and detection thresholds were obtained from 65 subjects during periods of both normal and reduced salivary flow. Decreased salivary flow was achieved by oral administration of either Elavil, Benadryl or atropine. Thresholds were measured for NaCl, citric acid, quinine sulphate and sucrose with a traditional series of aqueous solutions as well as with a series of dry taste stimuli using a filter-paper base. Whole mouth resting flow and stimulated salivary flow were measured before and after taste testing. The pharmacologic agents produced depressions in salivary flow ranging between 30 and 75 per cent of normal levels. The large decreases in flow produced no measurable changes in taste thresholds with the exception that an increased sensitivity to aqueous and dry citric acid stimuli consistently was observed following atropine administration. Changes in salivary bicarbonate levels, produced by atropine, may have mediated the observed shifts in oral sensitivity to citric acid.

Relationship of parotid saliva flow rate and composition with personality traits in healthy men

A number of studies have investigated the relationship between parotid saliva flow rate and clinical depression. However, no comprehensive study of the intercorrelations between parotid gland secretion and normal personality traits has been reported. The stimulated flow rate, pH, osmolality, and eleven composition variables were measured in 390 normal men and correlated against eight personality dimensions derived from scores obtained from the Cattell Sixteen Personality Factor questionnaire (16PF) and a modified form of the Eysenck Personality Inventory. Flow rate, pH, osmolality, and eight of the eleven salivary components were significantly correlated with four personality traits: anxiety, conscientiousness, shrewsness, and introversion. The relationship of personality traits to the parotid gland flow rate and saliva composition is discussed in terms of both physiologic models and the possible mediating effect by the sympathetic and parasympathetic nervous systems.

Fluoride in human parotid saliva

Gustatory stimulation was used to collect parotid saliva in an ascending flow rate pattern. F concentration was found to be independent of rate of flow. The F level in unstimulated parotid saliva, collected before the stimulate samplings, was significantly (P less than 0.01) higher than that for the stimulated collections. It is suggested that this is an apparent increase based on the movement of water out of the lumen, which is in turn triggered by sodium reabsorption. The level of F in unstimulated saliva increased almost tenfold within one hour after the oral administration of 10 mg of F, and a significant (P less than 0.01) increase persisted even at 24 hours after administration of the dosage.

[Clinical aspects of non-tumorous diseases of the salivary glands]

The vast field encompassed by the non-tumorous diseases of the salivary glands poses difficult problems for their diagnosis and therapy. In order to facilitate comprehension of the pathological processes and the therapeutical possibilities for their treatment, physiological and biochemical aspects of salivary gland function are presented in the introduction. There are also mentioned in detail most of the diagnostic methods clinically applied today and stress is laid on their respective diagnostic values. In contrast to the opinion of many authors, exploratory excision and puncture are shown to be very important diagnostic tools in salivary gland pathology. The specific application of these methods is often the only means for a reliable diagnosis. The classification of the diseases follows Seifert's (1971) proposal. The chronic diseases of the salivary glands are specifically mentioned with the chronic recurrent and the chronic myoepithelial sialoadenitis taking first place. The sialoses are presented in a larger chapter. An attempt was made to correlate clinical and experimental results, to establish working hypotheses concerning the development of sialoses, to suggest therapeutical possibilities and, last not least, to give an idea of the many clinical and patho-anatomical difficulties to be overcome for a satisfactory understanding of such pathological processes. Finally, various forms of salivary gland fistulas and their treatment are mentioned. The long list of references merely gives an approximation of the abundance of publications dealing with the problems of this field.

Circadian rhythms in human salivary flow rate and composition

1. Unstimulated whole saliva and parotid saliva stimulated at a constant flow rate of 1.0 ml./min were collected from eight subjects at about 07.00, 11.00, 14.00, 17.00 and 22.00 hr and oral temperature was recorded several times daily for time spans of between 4 and 26 days. A least-squares cosine wave was fitted to the data to test for the presence and characteristics of circadian rhythms.2. Estimates of mean level, amplitude, acrophase and period were obtained for different components and the results were subjected to cosinor analysis.3. Unstimulated whole saliva showed significant circadian rhythms in flow rate and in the concentrations of sodium and chloride but not in protein, potassium, calcium, phosphate or urea.4. Stimulated parotid saliva showed significant circadian rhythms in the concentrations of protein, sodium, potassium, calcium and chloride but not in phosphate or urea5. Oral temperature showed a circadian rhythm which, like the salivary rhythms, was of a 24.0 hr periodicity.