5-HT3A -driven green fluorescent protein delineates gustatory fibers innervating sour-responsive taste cells: A labeled line for sour taste?

Taste buds contain multiple cell types with each type expressing receptors and transduction components for a subset of taste qualities. The sour sensing cells, Type III cells, release serotonin (5-HT) in response to the presence of sour (acidic) tastants and this released 5-HT activates 5-HT3 receptors on the gustatory nerves. We show here, using 5-HT3A GFP mice, that 5-HT3 -expressing nerve fibers preferentially contact and receive synaptic contact from Type III taste cells. Further, these 5-HT3 -expressing nerve fibers terminate in a restricted central-lateral portion of the nucleus of the solitary tract (nTS)-the same area that shows increased c-Fos expression upon presentation of a sour tastant (30 mM citric acid). This acid stimulation also evokes c-Fos in the laterally adjacent mediodorsal spinal trigeminal nucleus (DMSp5), but this trigeminal activation is not associated with the presence of 5-HT3 -expressing nerve fibers as it is in the nTS. Rather, the neuronal activation in the trigeminal complex likely is attributable to direct depolarization of acid-sensitive trigeminal nerve fibers, for example, polymodal nociceptors, rather than through taste buds. Taken together, these findings suggest that transmission of sour taste information involves communication between Type III taste cells and 5-HT3 -expressing afferent nerve fibers that project to a restricted portion of the nTS consistent with a crude mapping of taste quality information in the primary gustatory nucleus.

Differences in bingeing behavior and cocaine reward following intermittent access to sucrose, glucose or fructose solutions.

Daily intermittent access to sugar solutions results in intense bouts of sugar intake (i.e. bingeing) in rats. Bingeing on sucrose, a disaccharide of glucose and fructose, has been associated with a "primed" mesolimbic dopamine (DA) pathway. Recent studies suggest glucose and fructose engage brain reward and energy-sensing mechanisms in opposing ways and may drive sucrose intake through unique neuronal circuits. Here, we examined in male Sprague-Dawley rats whether or not (1) intermittent access to isocaloric solutions of sucrose, glucose or fructose results in distinctive sugar-bingeing profiles and (2) previous sugar bingeing alters cocaine locomotor activation and/or reward, as determined by conditioned place preference (CPP). To encourage bingeing, rats were given 24-h access to water and 12-h-intermittent access to chow plus an intermittent bottle that contained water (control) or 8% solutions of sucrose, glucose or fructose for 9days, followed by ad libitum chow diet and a 10-day cocaine (15mg/kg; i.p.) CPP paradigm. By day 4 of the sugar-bingeing diet, sugar bingeing in the fructose group surpassed the glucose group, with the sucrose group being intermediate. All three sugar groups had similar chow and water intake throughout the diet. In contrast, controls exhibited chow bingeing by day 5 without altering water intake. Similar magnitudes of cocaine CPP were observed in rats with a history of sucrose, fructose or chow (control) bingeing. Notably, the glucose-bingeing rats did not demonstrate a significant cocaine CPP despite showing similar cocaine-induced locomotor activity as the other diet groups. Overall, these results show that fructose and glucose, the monosaccharide components of sucrose, produce divergent degrees of bingeing and cocaine reward.

Methods of assessing gingival and periodontal disease: a review.

There has been an effort by the dental profession working in the field of gingival and periodontal disease to find a method of recording the extent and degree of pathological change in tissues leading from gingivitis to periodontitis and to measure reversible as well as irreversible changes. It is obvious that some form of index is required and it should have the following well-defined criteria: (1) Simplicity, (2) Accuracy, (3) Quantitativeness, (4) Reproducibility, (5) Speed, (6) Objectivity, and (7) Amenability to statistical analysis. Indices, as well as determining the prevalence of disease in the group under investigation at a given period in time, must also provide information on incidence of disease, i.e. at different periods of time. Indices must also give data that make it possible to verify the nature, severity and aetiology of the disease process and to evaluate therapeutic measures. Indices yield information about the success or failure of control and prevention of disease, affecting the gingivae and the periodontal tissues. A review of methods of assessing and recording gingival and periodontal disease is presented starting from the early investigations of the century. It is shown that subsequently many variations evolved, often with the same inherent difficulties of interpretation or application. Usually the initial stages of inflammation of the gingivae are more difficult to recognize than established disease. Present methods of recording as objectively and as quickly as possible the gingival state in population groups are discussed with emphasis upon the necessity for providing effective preventive measures based upon assessment of schoolchildren.