Search PubMed⌕ Search

Biomedical subjects

A Sclafani

Publications and source records attributed to A Sclafani.

160 records · Page 9Linked to original sources
PubMed1975

Effects of hypothalamic knife cuts on the ingestive responses to glucose and insulin.

Parasagittal knife cuts through the perifornical hypothalamus either medial or lateral to the fornix produced hyperphagia and obesity and altered the rat's ingestive responses to dilute glucose solutions. The lateral knife cut rats drank less dilute glucose solution under both nondeprived and food deprived conditions and displayed less of a feeding suppressive response to glucose ingestion compared to controls. The lateral cut rats were also deficient in their feeding response to insulin-induced hypoglycemia, although their altered sensitivity to glucose and insulin did not appear to be causally related. The medial knife cuts decreased the responsivity to glucose, but less so than the lateral cuts, and did not alter the ingestive response to insulin. Both the medial and lateral knife cuts did not appear to change the rat's responsivity to concentrated blucose solutions. The neuroanatomical and functional nature of the disorder responsible for these effects and its relationship to the hyper-phagia-obesity syndrome are discussed.

Animals↗
PubMed1975

Multiple knife cuts between the medial and lateral hypothalamus in the rat: a reevaluation of hypothalamic feeding circuitry.

Single or multiple sets of bilateral knife cuts were made in female rats just lateral to the ventromedial hypothalamus (VMH) and/or just medial to the lateral hypothalamus (LH). The lateral VMH cuts by themselves produced greater hyperphagia and obesity than did the medial LH cuts. The lateral VMH knife cuts also significantly increased food intake and body weight in rats previously given bilateral cuts along the medial LH border. These findings indicate that the feeding inhibitory fibers responsible for the hyperphagia syndrome do not project from the VMH to the LH, and this calls for a reevaluation of hypothalamic circuitry. It was also discovered that sham surgery has a significant suppressive effect on the hyperphagia syndrome produced by hypothalamic knife cuts.

Animals↗
PubMedDate not supplied

Starch and sugar tastes in rodents: an update.

Rats are strongly attracted to the sweet taste of sugar. Recent behavioral studies demonstrate that rats also have a well-developed taste for starch-derived polysaccharides (e.g., Polycose). In fact, rats prefer Polycose to sucrose and other sugars at low concentrations. Polycose appetite develops at a very young age (9 days) and, thus, appears to be innate. The results of conditioned taste aversion tests suggest that rats taste Polycose as qualitatively different from sucrose. Recent electrophysiological findings support the idea that rodents have separate taste channels for polysaccharides and sugars. In particular, copper chloride suppresses the chorda tympani nerve response to sucrose and other sugars but has minimal effect on the neural response to Polycose. Also, Polycose evokes a profile of neural activity in the nucleus tractus solitarius that differs substantially from that produced by sucrose. Preliminary results indicate that polysaccharide and sugar tastes also differ in their metabolic consequences, i.e., unlike sugars, Polycose does not elicit a cephalic phase insulin response. The presumed function of polysaccharide taste is to facilitate the identification of starch-rich foods. Recent findings demonstrate that rats can readily detect starch even at low concentrations, but whether polysaccharide taste receptors or other orosensory receptors mediate this response remains to be clarified.

Animals↗
PubMedDate not supplied

Conditioned enhancement of flavor evaluation reinforced by intragastric glucose: I. Intake acceptance and preference analysis.

Rats acquire strong preferences for flavors that are paired with intragastric (IG) glucose infusions. The present study assessed the magnitude of this nutrient-conditioned change in flavor evaluation by comparing the strength of the rats' conditioned preference to their unconditioned preference for the sweet taste of sugar. Food-restricted rats were first trained (20 h/day) to associate one flavor (CS+) with IG 16% glucose infusions and another flavor (CS-) with IG water infusions. Then, in a series of 30 min/day two-bottle tests, the CS+ and CS- were separately offered in a choice vs. fructose of varying concentrations. The CS- was preferred to 2% fructose, but not 4% fructose. The CS+ was preferred to 2%, 4%, and 8% fructose and was isopreferred to 16% fructose. This CS+ vs. fructose preference profile was replicated and found to be independent of deprivation state. The intake-stimulating efficacy of the CS+ flavor and of fructose taste was also compared in one-bottle sham-feeding tests. Intakes of CS+ and of 16% fructose increased by similar amounts in the first sham-feeding test. However, with repeated testing, fructose intake continued to increase, whereas CS+ intake declined. This profile suggests extinction of the conditioned satiation response to fructose and extinction of the conditioned acceptance response to the CS+, respectively. These findings provide novel evidence for a robust learned shift in flavor evaluation reinforced by the postingestive actions of glucose.

Animals↗
PubMedDate not supplied

Conditioned enhancement of flavor evaluation reinforced by intragastric glucose. II. Taste reactivity analysis.

Rats learn to prefer a flavor that is paired with intragastric (IG) glucose infusion, which may represent a learned shift in the hedonic evaluation or palatability of the flavor. The present study used the taste reactivity (TR) test to infer nutrient-conditioned changes in flavor palatability. Rats were first conditioned in 20-h/day and then 30-min/day sessions to associate a flavored saccharin solution (the CS+) with IG infusions of 16% glucose, and a different flavored saccharin solution (the CS-) with IG water infusions. They strongly preferred the CS+ to the CS- in two-bottle intake tests. When next tested with brief intraoral (IO) infusions of the CS flavors, the rats exhibited significantly more hedonic TR responses to the CS+ flavor than the CS- flavor, which indicates an enhanced hedonic evaluation. A subsequent series of two-bottle tests established that the CS- flavor was equally preferred to 3% fructose, whereas the CS+ flavor was equally preferred to 16% fructose. In addition, the difference between the TR responses to 3% and 16% fructose paralleled the difference between the TR responses to CS- and CS+. These findings support the idea that pairing flavored saccharin with the postingestive effects of glucose produces a learned shift in palatability comparable to that produced by increasing the concentration of a sugar solution.

Animals↗