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D K Ingram

Publications and source records attributed to D K Ingram.

At least 163 records · Page 9Linked to original sources
PubMed1983

Differential effects of intermittent feeding and voluntary exercise on body weight and lifespan in adult rats.

Male wistar rats were housed in laboratory cages or activity-wheel cages at eight 10.5 or 18 months of age. Part of each cage group continued to be fed ad libitum, whereas the remaining animals were fed every other day. Compared with the ad libitum condition, intermittent feeding decreased body weight and increased lifespan at both ages in both caging conditions. Compared with the caged condition, voluntary exercise in activity wheels reduced body weight only in the 10.5-month-old group fed ad libitum but produced no effect on survival of either age group. The results suggest that intermittent feeding can enhance survival in mature rats even beyond ages at which body weight growth usually ceases, whereas voluntary exercise appears to have an early threshold beyond which increases in longevity are not observed.

Animals↗
PubMed1983

Influence of dietary carbohydrate on the induction of diabetes in C57BL/KsJ-db/db diabetes mice.

Genetically diabetic C57BL/KsJ-db/db and normal littermate mice of both sexes were fed one of nine defined diets from weaning. The objective was to study dietary carbohydrate interaction with the diabetogenic genes through isocaloric substitution of protein for carbohydrate (either sucrose or dextrin starch) at concentrations of 0, 8, 24, and 60%. In addition, at 60% concentration, the effect of type of carbohydrate (e.g., glucose, fructose, sucrose or dextrin starch) on the deterioration of endocrine pancreatic structure and function was analyzed. The carbohydrate-free diet produced the greatest survival to 1 year of age and allowed the expression of an obesity syndrome uncomplicated by severe hyperglycemia or by extensive necrosis of pancreatic beta cells and islet atrophy. Those diets containing intermediate levels of carbohydrate (8 or 24% of sucrose or dextrin), or 60% dextrin starch, in comparison to diets containing 60% refined carbohydrates, extended life span and produced a more protracted pathogenesis, but were unable to circumvent eventual severe hyperglycemia and islet destruction. The diets containing 60% glucose, fructose, or sucrose all led to the rapid induction of diabetes. Thus, pathogenesis entails an interaction between dietary carbohydrate, the db gene, and other diabetes-predisposing genes in the genome.

Animals↗
PubMed1983

Age and strain comparisons of neurotransmitter synthetic enzyme activities in the mouse.

Activities of the neurotransmitter synthetic enzymes, choline acetyltransferase (EC 2.3.1.6; ChAT), glutamic acid decarboxylase (EC 4.1.1.15; GAD), and tyrosine hydroxylase (EC 1.14.3.2; TH), were assayed in four brain regions of A/J and C57BL/6J mice at three ages (4, 18, and 24 months). The brain regions assayed were the fronto-parietal cortex, hippocampus, striatum, and cerebellum. Strain effects: In some brain regions, at several ages, ChAT activity did not differ among the two strains. However, ChAT was higher in the C57BL/6J strain in the cortex at 18 months, the hippocampus at 18 and 24 months, the striatum at 24 months, and the cerebellum at 4 months. The reverse was true in the cerebellum at 24 months, where ChAT was higher in A/J mice. GAD activity in C57BL/6J mice compared to that of A/J mice was higher in the striatum and cortex, and lower in the hippocampus and cerebellum. TH activities in all four regions were generally higher in C57BL/6J mice than in A/J mice. Age effects: Age differences in enzyme activities varied with the genetic strain. ChAT activity generally was higher in brain regions of older mice of both strains.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1982

Decreased resistance to extinction in ob/ob mice following operant training.

Inconsistent results have emerged from past studies in which operant conditioning paradigms were used to assess the hunger motivation of genetically obese mice relative to that of normal mice. Methodological considerations indicated the need to examine operant performance to a criterion, rather than performance during time-based sessions, and then to focus upon response differences in resistance to extinction. Therefore, genetically obese (ob/ob) mice and normal littermates were trained successfully to bar-press for 100 food rewards on either a CRF or a FR-10 schedule of reinforcement. Extinction behavior was then examined over 9 daily 1-hr sessions. While obese and normal mice evidenced similar patterns of learning, or response discrimination for food rewards, they evidenced different levels of hunger motivation during extinction conditions. Obese mice displayed a greater reduction in responding across extinction sessions, or less resistance to extinction, than normal mice following training on both schedules of reinforcement. These findings suggest that ob/ob mice exhibit lower levels of hunger motivation than normal littermates.

Animals↗
PubMed1982

The relationship of genotype, sex, body weight, and growth parameters to lifespan in inbred and hybrid mice.

Data from nine inbred and six hybrid mouse strains of both sexes were used in a correlational analysis to examine the relationships between lifespan and several growth parameters, including body weight at weaning, at 6 weeks after weaning, and at 1 year, and estimates of growth rate, food consumption, and feeding efficiency during early life. The analysis revealed strong relationships of genotype to all variables. Hybridization was associated with longer lifespan, but sex was not related to lifespan. Several growth parameters were significantly related to lifespan, but the directions of the correlations were sex-dependent. Several body weight and growth parameters were positively correlated to lifespan in males, while negatively correlated to lifespan in females. Genotype accounted for most of the variance in these relationships with the exception of hybrid males, where the correlation between growth rate and lifespan was attributable largely to environmental factors. In demonstrating significant correlations between lifespan and constitutional variables within a species, the results supported a morphogenetically based hypothesis of lifespan inheritance; however, the sex differential in the direction of the relationship between growth and lifespan further demonstrated the difficulty of making predictions deduced from the hypothesis.

Animals↗
PubMed1982

Circadian rhythmicity and sleep: effects of aging in laboratory animals.

This literature review of research on age-related differences in sleep and rhythmic phenomena in laboratory animals covers three general areas: (1) age-related differences in biorhythms in general; (2) age-related differences in sleep patterns as assessed by psychophysiological measures; and (3) neurobiological correlates of biorhythms and sleep, including consideration of possible morphological, chemical, and endocrine bases of age-related defects in animal models. It is concluded that systematic research bridging these areas is lacking although several promising areas have been explored.

Aging↗
PubMed1982

Physiological and behavioral correlates of lifespan in aged C57BL/6J mice.

Physiological and behavioral measurements were made in a cohort of 29-month-old male C57BL/6J mice to determine whether any correlated significantly with lifespan. Significant linear relationships with lifespan were found among the physiological measures, including hematocrit and hemoglobin levels and collagen denaturation rate; however, body weight failed to be a significant predictor of survival. Among the behavioral variables studied, significant quadratic relationships with lifespan were found for exploratory activity and passive avoidance learning, while performance on a rotorod and a tightwire showed no significant relationships with lifespan. Through the use of multiple regression techniques, about one-third of the variance in lifespan could be explained by a combination of physiological variables, and about two-fifths could be explained by a combination of behavioral variables.

Aging↗
PubMed1982

Relationship of sex, exercise, and growth rate of life span in the Wistar rat: a multivariate correlational approach.

Measures of body weight change were calculated and examined in relation to the life span of 68 male and 71 female Wistar rats that were maintained either in wheel-cage units of cages without wheels. The analysis revealed the following: (a) sex and wheel exercise accounted for nearly one third of the obtained variation in life span; (b) growth rate, defined as the ratio of peak body weight to growth duration, accounted for over 15% of the variance in life span unattributable to sex and exercise; (c) measures of body weight gain early in the developmental span were virtually unrelated to life span; (d) beyond 9 months of age, measures of body weight gain showed a significant positive relationship with life span. Thus, there was no evidence of a negative relationship between life span and body weight gain during early life.

Aging↗
PubMed1982

Effects of intermittent feeding upon growth and life span in rats.

From weaning to death, 28 male Wistar rats were maintained on an ad libitum (AL) diet, and 24 counterparts were provided the diet every-other-day (EOD). The mean life span of the EOD group represented an 83% increase over that of the AL group. Furthermore, a Gompertzian analysis of mortality rates suggested that the rate of aging was retarded in the EOD group. While body weight and growth rate were reduced in the EOD group, their growth duration was 75% longer compared to the AL group. Significant positive relationships emerged between life span and growth rate parameters in the AL group; however, no significant relationships were found between life span and body weight parameters in the EOD group. Therefore, in support of the hypothesis that dietary restriction effects prolongevity through retarded development, evidence was produced only in the between-group comparisons of AL- and EOD-fed animals.

Aging↗
PubMed1982

Lithium chloride-induced taste aversion in C57BL/6J and DBA/2J mice.

Male C57BL/6J and DBA/2J mice (Mus musculus) were tested in a one-bottle conditioned taste aversion paradigm with 15% sucrose as the conditioned stimulus and lithium chloride (LiCl) as the unconditioned stimulus. The results of a dose-response experiment yielded evidence that higher doses of LiCl than used in past studies were required to produce profound aversions in these mice, with a 6.0 mEq/kg dose appearing as optimal. When the mice were conditioned with the 6.0 mEq/kg dose in one-bottle tests, there was little evidence of a strain difference in the acquisition of a taste aversion. During extinction trials, however, DBA/2J mice exhibited stronger resistance to extinction than did C57BL/6J mice. Additional analyses of fluid consumption suggested that strain differences in drinking behavior were evident in the paradigm and that these must be considered in interpreting the strain differences observed in conditioned taste aversion.

Animals↗
PubMed1981

Dietary restriction retards the age-associated loss of rat striatal dopaminergic receptors.

In male Wistar rats subjected to dietary restriction by alternate days of feeding and fasting the normal age-associated loss of striatal dopamine receptors in the brain was substantially retarded. The mean survival time of the rats on the restricted diet was increased by approximately 40 percent compared to control rats given free access to food. Dopamine receptor concentrations in striata of 24-month-old rats that had been on a restricted diet since weaning were 50 percent higher than those of control animals of the same age, and essentially comparable to 3- and 6-month-old control rats.

Aging↗
PubMed1981

Differential effects of age on motor performance in two mouse strains.

The performance of male A/J and C57BL/6J mice from three age groups (4, 18, and 24 months) was observed in a battery of tests designed to assess age-related impairments in motor abilities. A/J mice were superior to C57BL/6J mice in tasks requiring upper body strength, such as tests of grip strength and tightrope performance. C57BL/6J mice were superior performers in tasks requiring balance and coordination, such as movement on stationary and rotating rods. In addition, the C57BL/6J strain generally exhibited greater locomotor activity, such as measured in open field and wheel-running tests. Significant age-related deficits were observe among A/J mice in tests of grip strength, balance rod, rotorod, and wheel activity; and among C57BL/6J mice, in balance, rod, tightrope, exploratory activity, and wheel activity tests. Except for scores of exploratory activity (free versus forced exploration), the test measures tended to be uncorrelated; however, the degree and magnitude of intercorrelation among test scores increased with age. The results underscore the need to consider genotype in the assessment of age-related motor impairments in animal models.

Aging↗
PubMed1981

Age and neurochemical correlates of radial maze performance in rats.

Young adult (8 months) and aged (26 months) female Wister rats were tested in a 12-arm radial maze in which the optimal strategy was to enter all arms without a repetition. In order to determine if possible age-associated alterations in behavior were correlated with defects in cholinergic. GABAergic and adrenergic neurons in the hippocampus and cerebral cortex, the activities of choline acetyltransferase (CAT), glutamic acid decarboxylase (GAD) and tyrosine hydroxylase (TH) were assayed in these regions of all animals after testing in the radial maze. In the maze, the aged rats continued to perform at the chance level after 15 trials, whereas the young rats had virtually mastered the task. The only significant neurochemical age effect was an increase in hippocampal TH. However, analysis of individual differences among rats revealed positive correlations between maze performance and hippocampal CAT in the aged group and cortical GAD in both the young and aged groups.

Aging↗
PubMed1980

An overview of neurobiological comparisons in mouse strains.

A literature review of research dealing with mouse strain comparisons along neurobiological parameters is presented in tabular form which provides a rank-ordering of strains and estimates of percentage differences in individual parameters. Drawing from 86 references, three tables deal respectively, with comparisons of neurochemical, neuroanatomical, and neuropsychophysiological parameters.

Aging↗
PubMed1980

Failure of B6 deficiency to affect performance of aging rats in a passive avoidance task.

Male Fischer-344 rats from three age groups (6-7, 15-16, and 27-29 months) were given either a pyridoxine deficient diet or control diet for five weeks. Differences in body weight produced by the diets were evident in the youngest age groups but not in the oldest group in which all animals tended to lose weight. There was no evidence that diet or age affected performance during passive avoidance learning.

Aging↗
PubMed1980

Conditioned taste aversion as a function of age in mature male rats.

Experimental groups of young mature (90-120 days), mature (365-395 days), and aged (730-760 days) Fischer-344 rats were allowed to drink a saccharin solution followed by lithium chloride toxicosis initiated at one of three intervals, either 15, 60, or 240 minutes. Control groups were given saline placebos according to the same schedule. In a preference test conducted 48 hours after conditioning, there was little evidence of age differences in the acquisition of a saccharin aversion. Age differences were noted in the extinction of the aversion which was tested by monitoring preference over a period of 32 days of continuous access to saccharin and water. Older animals tended to show greater resistance to extinction.

Aging↗