Interaction with demonstrator rats changes observer rats' affective responses to flavors.

The authors examined whether exposing naive rats (observers) to recently fed conspecific demonstrator rats changed the observers' later affective responses to foods their demonstrators ate. In Experiment 1, observers learned an aversion to a flavored fluid, then interacted with demonstrators that had drunk that fluid. These observers, but not those interacting with demonstrators that had drunk water, increased their intake of the averted fluid and exhibited fewer negative responses when the averted fluid was infused into their mouths. Rats in Experiment 2 entered the arm of a T maze known to lead to banana-flavored pellets more frequently after interacting with demonstrators fed banana-flavored pellets than after interacting with demonstrators fed chow-flavored pellets. Results of both experiments indicated that interaction with demonstrator rats changed observer rats' affective responses to flavors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Influence of diets with qualitatively different carbohydrates on lipid metabolism

Tissue cultures of HeLa cells in Hank's medium suspension, previously mixed with a solution containing reticulocyte polysomes and/or free globin, hemoglobin and blood plasma from bled rabbits, were homogenized, and an electrophoretic pattern of hemoglobin band was obtained from the supernatant; hemoglobin denatures under the tissue culture conditions. HeLa cells show typical hemosomes, identidical to those found in immature erythrocytes of embryos, and adult mammals with hemolytic anemias. When HeLa cell suspensions are mixed with solutions void of anemic blood plasma, or containing normal rabbit blood plasma, anomalous organelles are formed in the cells, and no hemoglobin biosynthesis occurs.     

Taste aversions to food flavors and vaginal secretion in golden hamsters.

Although rodents readily associate virtually any distinctive flavor with gastrointestinal illness when the flavor and illness have been paired, experience with a flavor can provide information that interferes with later attempts to produce aversions to the familiar taste. The vaginal secretion of female hamsters carries sexual information for males, which does not depend on previous experience; it was studied, in the present 3 experiments, whether that built-in information might interfere with associations between flavor of the excretion and illness. Surprisingly, the Ss, 32 male Syrian hamsters, showed dramatic changes in behavior toward the vaginal secretion when its presentation was followed by lithium chloride poisoning. Results suggest that mammalian responses to sex pheromones are far more easily modified by experience than has been supposed. (30 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Stimulus preexposure reduces generalization of conditioned taste aversions between alcohol and non-alcohol flavors in infant rats.

Results of 3 experiments showed that infant rats (age 13-17 days) generalize conditioned taste aversions between alcohol and non-alcohol tastes such as a mixture of sucrose and quinine, apple cider vinegar, or coffee. Nonreinforced preexposure to those tastes reduced generalized aversions between them. Generalization between alcohol and sucrose-quinine was reduced not only after preexposure to both tastes, but also when only the nonconditioned taste was preexposed, whereas with alcohol and vinegar, both tastes had to be preexposed to obtain that effect. In no case was generalization reduced when only the to-be-conditioned taste was preexposed. Previous experience with alcohol alone, as well as with similar gustatory stimuli, may enhance subjects' ability to differentiate them during infantile stages in rats. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Female Wistar-Kyoto and SHR/y rats have the same genotype but different patterns of expression of renin and angiotensinogen genes

BACKGROUND: Prevalence estimates vary 2750-fold among the 20 studies of essential tremor (ET). It is not clear how the choice of diagnostic criteria affects research results. OBJECTIVE: To determine the impact of alternative sets of diagnostic criteria on the diagnosis of ET. METHODS: As part of the Washington Heights-Inwood Genetic Study of ET (WHIGET), a population-based study of ET, 285 subjects who include 36 case subjects with probable or definite ET, 34 case subjects with possible ET, and 215 normal subjects were interviewed and examined. All diagnoses in WHIGET were assigned by 2 neurologists. Ten of the 20 published prevalence studies of ET provided diagnostic criteria for ET. Criteria differed in terms of requirements for the distribution, duration, and severity of tremor. These 10 sets of criteria were then each separately applied to the subjects in the WHIGET cohort to determine their impact on the diagnosis of ET. RESULTS: Depending on which diagnostic criteria were applied to the WHIGET cohort, the proportion of WHIGET case subjects with definite or probable ET who would have been diagnosed as having ET was as low as 14% and the proportion of WHIGET normal subjects who would have been diagnosed as having ET was as high as 51%. Diagnostic criteria that included a positive family history of ET or a lengthy duration of tremor would have classified many WHIGET case subjects with ET as normal, whereas criteria that did not specify a minimal tremor severity would have classified many WHIGET normal subjects as having ET. CONCLUSIONS: Alternative sets of diagnostic criteria for ET greatly impact on the diagnosis of ET. For population-based studies, information on tremor type and severity rather than family history should be included in diagnostic criteria.     

Evidence that oral and nutrient reinforcers differentially condition appetitive and consummatory responses to flavors

Rats tend to increase their intake of a flavor that has previously been paired with either sweet taste or with caloric repletion. However, it is unclear whether such a change in intake is caused by changes in appetitive behaviors such as orienting and approach, or changes in consummatory behaviors and oral responsiveness. Also, it is unclear whether oral reinforcers (sweetness) and postingestive reinforcers (nutrients) lead to the same kinds of behavioral change. In the current experiments, weanling rats with oral and gastric cannulas repeatedly experienced a flavor paired with either sweetness, high caloric density, or neither. Rats were then tested for differences in appetitive olfactory orienting and consummatory oral responsiveness elicited by the flavor. Results suggest that oral reinforcement (sweetness) produces conditioning of appetitive responding to the flavor, while postingestive reinforcement produces conditioning of consummatory responding. A second experiment indicates that these behavioral changes are specific increases in responsiveness conditioned by flavor + unconditioned stimulus (US) pairing, and are unlikely to be nonspecific effects of daily unconditioned stimulus exposure.     

Constraints have different concurrent effects and aftereffects on variability.

Three experiments showed that constraints imposed early in learning have different effects on variability when they are in effect and after they are removed. Task constraints, which determine how something can be done, limited the number of possible responses in a computer game. Variability constraints, which specify how differently something must be done, required that each response differ from some number of prior responses. Less restrictive constraints (Experiments 1 and 2) produced higher variability during the constraints. More restrictive constraints (Experiments 2 and 3) led to higher variability after the constraints were relaxed. The authors discuss how these differences reflect strategies acquired during the constraints (default rules) and modified in closely related ways (exception rules) afterward. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Do tricyclic responders have different brain laterality?

A previous study showed that depressed patients who improved with tricyclic antidepressant medication had dichotic complex tones test results suggesting right-hemisphere dysfunction relative to nonresponders and controls (G. E. Bruder et al., 1990). A new sample of 68 depressed patients completed dichotic consonant-vowel (CV) and complex tones (CT) tests and then were treated with imipramine or placebo. A significant Ear?×?Test?×?Treatment?×?Response interaction was accounted for by significantly poorer left-ear accuracy for CVs among imipramine responders compared with nonresponders, placebo responders, and controls. CV left-ear accuracy was also significantly greater among placebo responders than placebo nonresponders; and controls. The results only partially replicate the prior study in that evidence of right-hemisphere dysfunction in tricyclic responders was seen for the CV test but not the CT test. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Do depressed patients in different treatment settings have different levels of well-being and functioning?

Differences in the functioning and well-being of adult patients with current or past depressive disorder who visited clinicians of different specialties in HMOs, solo practices, or large multispecialty group practices were examined. For patients in different systems, there were no significant differences in functioning and well-being across 12 domains tested. Patients of mental health specialists had worse mental health and more limitations in social activities, whereas patients of medical clinicians had worse physical functioning, more pain, more physical/psychophysiologic symptoms, and worse health perceptions. Thus, each system of care had depressed patients with a similar functioning and well-being "burden," but specialty sectors had patients with slightly different functioning and well-being profiles, probably reflecting patient selection of type of provider. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of rilmenidine on rats made insulin resistant and hypertensive by a high fructose diet

This study was aimed to determine the effects of rilmenidine, an hypertensive drug, in an animal model of hypertension associated with insulin resistance, i.e. rats fed on a high fructose diet. Wistar rats were fed during four weeks either on a standard diet (S) or on a high fructose diet (F, 34.5% de fructose). In half of the F groups, rilmenidine (1 mg/kg/day) was added to the drinking water during the two last weeks of the diet (FR). Arterial blood pressure as well as insulin efficiency were determined at the end of the four weeks. Body weight gain was higher in F than in S rats (66 +/- 8 g versus 45 +/- 8 g; p < 0.05), this was prevented by rilmenidine treatment (32 +/- 2 g). Arterial systolic blood pressure was increased in F rats (162 +/- 2 vs 155 +/- 2 mmHg; p < 0.05), rilmenidine brought this value back to normal (149 +/- 3 mmHg). During the euglycemic hyperinsulinemic clamp, glucose utilization was lower (10 +/- 1 vs 14 +/- 1.5 mg/min/kg; p < 0.05) and hepatic glucose production higher (1 +/- 0.01 vs 0 mg/min/kg; p < 0.01) in F than in S rats. These changes in insulin action were totally abolished by rilmenidine. These data demonstrate that rilmenidine can ameliorate the deleterious effects of a high fructose diet, i.e. weight gain, hypertension and resistance to the effects of insulin Rilmenidine could represent a potential therapeutic agent for the treatment of hypertension associated with metabolic disorders such as syndrom X and obesity.     

Sucrose preferences of hungry and thirsty rats as a function of duration of stimulus presentation.

Studied sucrose preference in 3 experiments with 6, 12, and 12 male Holtzman albino rats. With progressively shorter intervals of repeated stimulus presentation (continuous down to 10 sec/min) in 2-choice brief exposure tests, thirsty Ss dropped from 90-50% preference for 6 or 12% sucrose over water, and showed little preference for 12 over 6%. Hungry Ss maintained a 90% preference for sucrose over water at all intervals but showed a decrement for 12 over 6% sucrose. For thirsty Ss (a) sucrose preference was a joint function of amount of exposure time and time between exposures, and (b) presentation order of different exposure durations was important. Results are discussed in terms of approach "arousal" and "decay" as a function of concentration and type of deprivation. (20 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Membrane-Transport Systems for Sucrose in Relation to Whole-Plant Carbon Partitioning

T Sucrose is the principal product of photosynthesis used for the distribution of assimilated carbon in plants. Transport mechanisms and efficiency influence photosynthetic productivity by relieving product inhibition and contribute to plant vigor by controlling source/sink relationships and biomass partitioning. Sucrose is synthesized in the cytoplasm and may move cell to cell through plasmodesmata or may cross membranes to be compartmentalized or exported to the apoplasm for uptake into adjacent cells. As a relatively large polar compound, sucrose requires proteins to facilitate efficient membrane transport. Transport across the tonoplast by facilitated diffusion, antiport with protons, and symport with protons have been proposed; for transport across plasma membranes, symport with protons and a mechanism resembling facilitated diffusion are evident. Despite decades of research, only symport with protons is well established at the molecular level. This review aims to integrate recent and older studies on sucrose flux across membranes with principles of whole-plant carbon partitioning.     

Biochemical and ultra-structural reactions to parenteral nutrition with two different fat emulsions in rats

OBJECTIVE: To compare the effects on fat metabolism and Kupffer cell morphology by total parenteral nutrition (TPN) with two different fat emulsions. DESIGN: Thirty-two male Sprague-Dawley rats, divided into three groups, were investigated. Rats fed orally were used as a reference group, and a group of rats receiving TPN with fat emulsions containing pure long-chain triglycerides (LCT) was compared to a group of rats receiving fat emulsions containing both long-chain triglycerides and medium-chain triglycerides (MCT/LCT). The TPN regimens were equicaloric and administered continuously via a jugular catheter for 10 days. INTERVENTIONS: After suffocation, blood of the rats was collected for the determination of serum lipids. Epididymal fat and heart were collected for the analysis of lipoprotein lipase (LPL) activities, and liver specimens were saved for analyses of hepatic triglyceride concentration, as well as activities of hepatic lipase (HL) and lysosomal enzymes. Light and electron microscopy were used for examination of the Kupffer cell reaction. RESULTS: Directly after termination of parenteral feeding, the levels of serum triglycerides and high density lipoprotein (HDL) triglycerides were higher in the MCT/LCT group than in the LCT group, while no differences concerning cholesterol and phospholipid concentrations were found. No significant difference in liver steatosis was found between the two TPN groups. Comparison of the TPN groups showed that the MCT/ LCT group had significantly decreased LPL activity in adipose tissue, while the LCT group had significantly increased LPL activity in the heart. The activity of HL was low in both groups, but significantly lower in the LCT group. Lipid accumulation and an increased number of lysosomes were found in all Kupffer cell when TPN with LCTemulsions was used. Moreover, TPN induced a pronounced increase in various liver lysosomal enzyme activities, but there was no notable difference between LCT and MCT/LCT effects. CONCLUSIONS: Compared to treatment with pure LCTemulsions, treatment with MCT/LCT emulsions evoked weaker biochemical reactions in terms of lower activity of lipoprotein lipase in fat and heart together with higher serum and HDL triglyceride levels. Morphological signs of increased Kupffer cell activity such as the appearance of multiple lysosomes and fat vacuoles in the cytoplasm followed treatment with pure LCT emulsions. However, both TPN groups showed a marked increase in activities of liver lysosomal enzymes.