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Biomedical subjects

C M Mistretta

Publications and source records attributed to C M Mistretta.

At least 37 records · Page 2Linked to original sources
PubMed1986

Quantitative anatomical study of taste buds in fungiform papillae of young and old Fischer rats.

To determine if differences in neural taste responses relate to taste bud loss in old age, taste buds were counted in fungiform papillae of Fischer 344 rats aged 4 to 6 months, 20 to 24 months, and 30 to 37 months. Papillae anterior to the intermolar eminence on one half of the tongue were examined in serial sections. Presence or absence of a taste bud was noted and taste bud diameter was measured. Average percentages of papillae that contained a taste bud in the three groups were 99.6, 99.3, and 94.7%. This is a significant age-related difference but actual number of taste buds lost in the oldest rats was small. Taste bud diameter did not differ with age and general anatomical characteristics of buds were similar in all groups. Thus, anatomical observations on taste bud maintenance in rats over a wide age range, coupled with neurophysiological data, demonstrate that the integrity of the peripheral gustatory system is not altered greatly in old age.

Aging↗
PubMed1985

Transganglionic transport of HRP from the circumvallate papilla of the rat.

To learn whether horseradish peroxidase (HRP) injections in gustatory papillae on the tongue can be used to study central topographical projections of taste buds and papillae, injections were made into the circumvallate papilla in rats. Labeled central projections after papilla injections were compared to projections after applying HRP to the cut glossopharyngeal nerve. Papilla injections result in HRP transport by afferent and efferent fibers of the glossopharyngeal nerve, and the pattern of central projections is similar to that after labeling the cut nerve. Projections include a separation in the brainstem of afferent, dorsally located fibers and efferent, ventrally located fibers. Afferent fibers project to the solitary nucleus and the trigeminal system. Efferent projections label muscle motorneurons in the nucleus ambiguus and the cells of origin of parasympathetic preganglionic fibers, which from the inferior salivatory nucleus. The parasympathetic neurons labeled after papilla projections are preganglionic fibers to Remak's ganglia in the tongue; post-ganglionic fibers of these ganglia are the secretomotor supply to the von Ebner's glands. In summary, injections of HRP into gustatory papillae reliably label central projections of the papilla and can be used for studies to discern topography in central projections of the taste system. Injections into the circumvallate papilla also have demonstrated that the parasympathetic neurons innervating von Ebner's glands are located in the inferior salivatory nucleus.

Animals↗
PubMed1985

Age does not affect numbers of taste buds and papillae in adult rhesus monkeys.

Taste buds and papillae in tongues of rhesus monkeys were examined and counted to determine if there are age-related differences in general morphology or numbers of receptor organs. Tongues from 15 monkeys in five groups aged 4-31 years were studied with light microscopy. Fungiform, circumvallate, and foliate papillae were examined and taste buds in each papilla type were counted. Numbers of papillae did not differ with age through 31 years; however, at 24 years and older, fungiform papillae were reduced in number in some animals that had lost tongue tips due to trauma. There were no age-related differences in numbers of taste buds in any of the three gustatory papilla types, nor did taste bud diameter alter with age. From data on each papilla type, estimates were made of total numbers of lingual taste buds. Totals ranged from about 8,000 to 10,000 and there were no age-related differences. These results support other recent reports that taste buds are not decreased in number in old rats or humans. Since taste bud numbers and general morphology are maintained even in old age, any age-related differences in taste behavior cannot be attributed to gross degenerative changes in lingual taste buds.

Aging↗
PubMed1984

Maintenance of chorda tympani salt taste responses after nerve transection in rats.

To determine whether neurophysiological responses to salts change differentially or in parallel during long recording sessions after nerve transection, we recorded from the cut chorda tympani nerve in rats while stimulating the anterior tongue with NaCl, LiCl, NH4Cl and KCl. In nerve preparations that were not disturbed once recording began, responses were maintained at or above initial magnitudes for an average of 10 h and declined to 50% by 15 h. If the cut end of the nerve was redissected when responses began to decline, stable responses were maintained for an average of 12 h, and did not decline to 50% until 21-24 h. In all rats, responses to the 4 salts altered in parallel for at least 19 h. However in two animals, after 23 h the responses to NaCl and LiCl declined disproportionately, relative to NH4Cl and KCl. Therefore in the course of a typical recording session, i.e. 10-12 h, stable taste responses are obtained and even when responses begin to decline after longer periods, response magnitudes to 4 salts alter in parallel. This indicates that receptor membrane components interacting with specific monochloride salts do not degenerate differentially during the first 19 h after nerve cut.

Ammonium Chloride↗
PubMed1984

Quantitative study of taste buds in fungiform and circumvallate papillae of young and aged rats.

To ascertain whether an age-related decrease in number of taste buds occurs in the tongue of aged rats, taste buds were counted in fungiform and circumvallate papillae of Wistar-derived rats aged 5-7 months and 23-24 months. There was no difference in number or size of taste buds in papillae in anterior and posterior areas of the tongue from the two age groups. However, both fungiform and circumvallate papillae were larger in old rats. These results complement a recent study demonstrating no difference in numbers of taste buds in human fungiform papillae from birth to old age (Arvidson, 1979). Both anatomical investigations and human taste threshold studies indicate that age-related differences in the gustatory system are not as substantial as investigators have suggested in the past.

Aging↗
PubMed1983

Superior laryngeal nerve response patterns to chemical stimulation of sheep epiglottis.

Responses were recorded from single fibers of the sheep superior laryngeal nerve during stimulation of the epiglottis with 0.5 M KCl, NH4Cl, NaCl and LiCl, distilled water, 0.005 M citric acid, and 0.01 N HCl. Recordings were made from both lambs and ewes. KCl elicited a response from 99% of fibers followed in order of effective stimulation by NH4Cl, HCl, distilled water, citric acid, NaCl and LiCl. Analysis of the variation in response frequency with time demonstrated differences in the response patterns for these stimuli. The pattern of frequency over time is sufficient to discriminate among the salts, between some of the salts and acids, and between some of the salts and water. Therefore the response pattern may be significant in initiating the various reflex activities that occur during chemical stimulation of the larynx.

Aging↗
PubMed1983

Neural basis of developing salt taste sensation: response changes in fetal, postnatal, and adult sheep.

To learn whether salt taste responses change during mammalian development, we recorded from multifiber preparations of the chorda tympani while stimulating the anterior tongue in sheep fetuses, lambs, and adults. Stimuli were 0.5 M NH4Cl, KCl, NaCl, and LiCl, and 0.05-0.75 M concentration series of the first three salts. Ultrastructural studies were made of taste buds at different ages to determine whether morphological elements such as microvilli and tight junctions are present in young fetuses. Substantial changes occur in relative salt taste responses, throughout development. In fetuses that are beginning the last third of gestation, NaCl and LiCl elicit much smaller response magnitudes than NH4Cl and KCl. Throughout the rest of gestation and postnatally, the NaCl and LiCl responses gradually increase in magnitude relative to NH4Cl and KCl. In adults, NaCl, LiCl, and NH4Cl all elicit similar response magnitudes and KCl is less effective as a taste stimulus. At ages when response ratios for the 0.5 M salts are changing, there are no changes in shapes of the response/concentration functions for individual salts. Furthermore, microvilli are present on taste bud cell apices and tight junctions are found between cells in the youngest fetuses studied. Therefore, initial stimulus-receptor membrane contacts are probably similar to those in adults. Our data suggest that different membrane components interact with the various monochloride salts and that taste receptors contain different proportions of these various membrane components at different developmental stages. Therefore young taste bud cells do not have the same salt response characteristics as mature cells, and a changing neural substrate underlies development of salt taste function, both pre- and postnatally.

Animals↗
PubMed1983

Developmental changes in taste responses from glossopharyngeal nerve in sheep and comparisons with chorda tympani responses.

To learn whether there are developmental changes in salt and acid taste responses from the posterior tongue, we recorded from the glossopharyngeal nerve, which innervates taste buds in circumvallate papillae, in sheep fetuses, lambs and adults. Multifiber responses to NH4Cl, KCl, NaCl, LiCl, citric and hydrochloric acids were expressed as ratios, relative to responses for two standard chemicals, NH4Cl and KCl. Response ratios for NaCl and LiCl, relative to either standard, increased during development, but the magnitude of the change was small. KCl elicited very large magnitude responses, relative to NH4Cl, in the youngest fetuses, and then decreased by 50% in stimulating effectiveness. Relative responses to both acids also decreased developmentally. The general shapes of KCl response-concentration functions did not change throughout development; however, in the youngest fetuses, the NH4Cl responses-concentration function was not similar to that in older animals. These developmental changes are different than those for responses from anterior tongue taste buds recorded from the chorda tympani nerve. Anterior tongue responses to NaCl and LiCl change most substantially and those to KCl change very little; acid responses do not change. The developmental differences for anterior versus posterior tongue responses suggest that membrane composition and maturational changes of taste buds in the two locations are not the same. Response-concentration functions from both tongue areas support the proposition that specific membrane components interacting with various salts are added during development.

Aging↗
PubMed1983

Development of taste responses in rat nucleus of solitary tract.

Extracellular responses from neurons in the nucleus of the solitary tract (NST) were studied in rats aged 5 days to adulthood during chemical stimulation of the tongue with monochloride salts, citric and hydrochloric acids, sucrose, sodium saccharin, and quinine hydrochloride. Multiunit taste responses were recorded in rats at 5-7 days of age and single-unit responses were recorded from 111 neurons in four other age groups of 14-20 days, 25-35 days, 50-60 days, and adult. NST neurons in rats aged 5-7 days consistently responded to relatively high concentrations (0.5 M) of NH4Cl and KCl and to citric and hydrochloric acid. However, they often did not respond to 0.5 M NaCl or to 0.1 M NH4Cl. Single NST neurons in rats aged 14 days and older characteristically responded to all 0.1 and 0.5 M salts and to both acids. At least 75% of neurons also responded to sucrose and sodium saccharin, and 46% responded to all of these stimuli and quinine hydrochloride. After 14 days, no developmental changes occurred in the number of stimuli to which neurons responded. There were substantial developmental alterations in the response magnitudes to some chemical stimuli. Average response frequencies increased after 35 days of age for 0.1 and 0.5 M NaCl, LiCl, KCl, and for sucrose and sodium saccharin. Response frequencies for NH4Cl, citric and hydrochloric acid, and quinine hydrochloride, however, did not change throughout development. The proportion of single NST neurons that responded maximally to specific monochloride salts did not change during development. Most single neurons in all age groups responded equally well to NH4Cl, NaCl, and LiCl. No NST neuron responded maximally to KCl. There were also no developmental differences in response latencies in rats aged 14 days and older. Response frequencies of second-order NST neurons generally reflect changes in responses from the primary afferent, chorda tympani fibers, throughout development; however, the increases in salt response frequencies from NST neurons occur comparatively later in development. Furthermore, at all ages, the taste responses to monochloride salts include higher response frequencies and a general loss in response specificity in NST compared to chorda tympani neurons.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1983

A quantitative study of cat epiglottal taste buds during development.

To quantify the development of upper airway chemoreceptors, epiglottal taste buds were counted in cat fetuses, kittens and adults. Taste buds with structural characteristics similar to those in the adult were observed in all fetuses close to term and in kittens from birth. During the first postnatal week a mean of 76 taste buds was present on the kitten epiglottis and by adulthood 800 were observed. The number of taste buds increased as a logarithmic function of both age and weight, but the correlation with weight is better than that with age. The presence of epiglottal taste buds from very early developmental stages suggests that these receptors may mediate the reflex apnoea and swallowing that occur in response to chemical stimulation of the larynx in newborns.

Aging↗
PubMed1982

Sucrose taste thresholds: age-related differences.

Sucrose taste detection thresholds were measured in 71 adults aged 20 to 88 years. A forced-choice, tracking procedure was used to eliminate subject response bias and rinses were included between all stimuli. A significant age-related decrease in sensitivity was observed. However, the loss of sensitivity was not great and elderly people had highly variable thresholds. A similar study on salt taste acuity has been reported from this laboratory demonstrating a small, but statistically significant threshold increment with age. The observation that age-related differences in taste sensitivity are not large is consistent with biological information that taste bud cells are continuously replaced in adult mammals.

Adult↗
PubMed1981

Development of chorda tympani taste responses in rat.

To learn whether neurophysiological taste responses change during structural development of the gustatory system, we recorded from the chorda tympani nerve in rats aged 7 to 92 days after birth. Chemical stimuli applied to the anterior tongue included four monochloride salts, two acids, sucrose, and urea. Responses to all chemicals were obtained as early as 7 days postnatally. Developmental changes in salt, acid, and sucrose responses were observed. Relative to NaCl and LiCl, NH4Cl and KCl gradually decrease in effectiveness as taste stimuli; or, relative to NH4Cl and KCl, NaCl and LiCl become more effective stimuli. These changes are similar to those observed prenatally and postnatally in sheep. Also, relative to NaCl, citric acid, hydrochloric acid, and sucrose become less effective stimuli; or, NaC1 becomes more effective as a stimulus, relative to these acids and sucrose. The period of most rapid functional change overlaps a period of rapid structural change. It seems most reasonable to hypothesize that the altering taste responses reflect developmental changes in receptor membrane composition. Since the taste system is not programmed to respond in a mature manner from the moment function begins, there is ample opportunity for changing taste experience to influence the developing taste system.

Aging↗
PubMed1981

Tactile sensitivity as a function of age.

To learn whether tactile sensitivity is decreased in elderly adults, we measured touch thresholds on the pad of the index finger in individuals aged 19 to 88 years. Semmes-Weinstein aesthesiometer filaments were used in a forced-choice procedure to eliminate response biases among subjects. Digit temperature and health data were also collected. Tactile thresholds increased significantly with age. A large proportion of elderly individuals had thresholds that were higher than the average for young adults, although older people varied widely in touch sensitivity. Neither reported illness nor medication use was significantly related in tactile threshold.

Adult↗
PubMed1980

Developmental changes in neurophysiological taste responses from the medulla in sheep.

To determine whether functional characteristics of the taste system change during development, electrophysiological taste responses were recorded from neurons in the solitary complex (nucleus and tractus solitarius) in the medulla of fetal, newborn and adult sheep. Taste stimuli included NH4Cl, KCl, NaCl, LiCl, citric acid, and HCl, applied to the anterior tongue. Fetal neurons at all ages (84-137 days of gestation) responded to stimulation of the tongue with NH4Cl and KCl, but responses to NaCl and LiCl were only obtained in older fetuses (after 114 days of gestation), lambs and adults. Responses to citric aicd were obtained at all ages; however, HCl responses were only infrequently obtained in young fetuses. Other developmental changes included a progressive decrease in latency of the responses to NH4Cl, KCl, citric acid and HCl, and an increase in the duration of the neural response discharge as a function of gestational age. Since taste buds do not acquire the structural characteristics of the adult until the last third of gestation (approximately 100-147 days), these functional changes in taste response characteristics take place concurrently with structural development. Mammalian fetuses swallow amniotic fluid in utero, and, therefore, the fetal taste system is stimulated during structural and functional development. Thus, there is an opportunity for fetal gustatory experience to influence the developing taste system.

Aging↗
PubMed1979

Age-related differences in salt taste acuity.

Salt taste detection thresholds were measured in 76 adults aged 23 to 92 years using a forced-choice staircase procedure, with distilled water rinses between all stimuli. Although an age-related decrease in salt taste acuity was observed, the decrement was smaller than previously reported in other studies. Past reports have probably exaggerated taste deficits in the elderly, because adequate rinse procedures and controls for subject response biases have not been incorporated in threshold measures.

Adult↗
PubMed1978

Taste responses in sheep medulla: changes during development.

Response characteristics of taste neurons in the sheep solitary tract and nuclei alter during development. Solitary tract cells in younger fetuses respond to stimulation of the tongue with fewer salts and acids than do cells in older fetuses, lambs, and adults. Further, responses to specific salts and acids develop in a particular sequence, not randomly. These changes may relate to maturation of taste receptor sites.

Age Factors↗