Long-Term Studies of Feeding Behavior of Obese, Diabetic, and Viable Yellow Mutant Mice under Ad Lib. and Operant Conditions

The feeding behavior of obese ( ob/ob), diabetic ( db2s/ db2s), and viable yellow ( Avv/a) mice was assessed in 2 separate experiments. When given access to solid food and sweet liquid food simultaneously, fat mutant mice ingest large quantities of sweet liquid food and gain weight more rapidly than controls. The behavior of diabetic and obese mice in this situation is quite similar. When given access to sweet liquid food reinforcement in an operant conditioning situation the behavior of the three mutant genotypes differs. The response rate of obese mice does not appear to be schedule dependent, while that of viable yellow mice clearly is schedule dependent. The response rates of viable yellow mice are consistently higher than the rates of their controls. The behavior of a diabetic mouse does not appear different from that of a control mouse in this situation. The use of mutant genotypes as “natural preparations” comparable to experimentally induced lesions is discussed.

Diet and calorie restriction

Current data suggest that the life spans of commonly held rodent species have decreased and the occurrence of tumors occurs earlier in the lifespan of ad libitum-fed animals. The most likely cause of this change in the life span of barrier-reared genetically defined animals is increased body weight. The effects of caloric restriction on a variety of functional measures and on age-dependent tumors and lesions are the focus of this presentation. Recommendations for caloric restriction, or at least "dietary control," will be discussed.

Mouse and rat genotype choices

There are advantages and disadvantages to all animal models for aging research. Investigators need to understand these issues, as well as the nature of each relevant model, to choose the best model for their research. There is no, "best" or "worst" model for aging research. Five genetically defined rodent models of potential utility in aging research are: (1) inbred strains and F1 hybrid mice and rats, (2) single gene mutations and other single locus effects, (3) congenic lines, (4) recombinant Inbred (RI) strains, and (5) genetically selected strains and stocks. Animals of each of these types are available for research, but only inbred and F1 hybrid mice and rats are commercially available as aged animals. A genetic understanding of the need for careful genetic definition and for the best available barriér-breeding facilities has improved the quality of aging research significantly in the last one decades.

FRAR course on laboratory approaches to aging. Mouse and rat genotype choices

There are advantages and disadvantages to all animal models for aging research. Investigators need to understand these issues as well as the nature of each relevant model, in order to choose the best model for their research. There is no "best" or "worst" model for aging research. Five genetically defined rodent models of potential utility in aging research are: 1. Inbred strains and F1 Hybrid mice and rats; 2. Single gene mutations and other single locus effects; 3. Congenic lines; 4. Recombinant Inbred (RI) strains; 5. Genetically selected strains and stocks. Animals of each of these types are available for research, but only inbred and F1 hybrid mice and rats are commercially available as aged animals. A general understanding of the need for careful genetic definition and for the best available barrier-breeding facilities has improved the quality of aging research significantly in the last two decades.

Development of animal models of aging at the National Institute of Aging

The suitability of various animal species as experimental models of aging has been a continuing concern of the National Institute on Aging (NIA) for over 20 years. The history of the decisions made by NIA in providing aged animals for research may be helpful to individual investigators seeking to understand why certain models are available and which of them to choose for their work.

Biomarkers of aging

This article presents a conceptual discussion of some aspects involved in biomarkers of aging. A biomarker of aging is a biological parameter of an organism that either alone or in some multivariate composite will, in the absence of disease, better predict functional capability at some late age than will chronological age. The reasons for undertaking biomarker research, criteria for putative biomarkers, measurement and assessment of putative biomarkers, and the new initiative by the National Institute on Aging in biomarker research are discussed.

The effects of age and genotype upon the jaw-jerk reflex in inbred mice

The threshold of the jaw-jerk reflex to electrical stimulation of the hard palate was measured in a cross-sectional design using C57BL/6J and DBA/2J mice at 2, 8, 20, 25, and 30 mo of age, in order to assess CNS sensitivity as a function of increasing age. The thresholds of DBA/2J mice were higher than those of C57BL/6J mice at all ages tested. No age-related changes in threshold were observed in mice of either strain.

Effects of situational variables on performance of inbred mice in active- and passive-avoidance situations

A group of experiments were conducted to assess the interaction between environmental factors and specific genetic loci upon the performance of mice in avoidance learning situations. The performance of all mice was better in passive-avoidance than in active-avoidance situations. The performance of C57BL/6J mice was generally superior to that of DBA/2J mice. C57BL/6J mice usually avoided foot-shocks, while DBA/2J mice attempted to escape them. DBA/2J mice performed poorly in the presence of mild foot-shocks, while C57-BL/6J mice performed poorly in the presence of intense foot-shocks. Analysis of the data suggested that the loci involved probably exerted their influence by affecting the subject's response to its environment.

Behavioral characteristics of C57BL/6J. DBA/2J, and B6D2F1 mice which are potentially useful for gerontological research

This review summarizes the behavioral characteristics of C57BL/6J, DBA/2J, and B6D2F1, hybrid mice which are most likely to be of interest to gerontological scientists. Where possible, the characteristics of young and old mice are included. Where no information exists about the behavior of older mice of these genotypes, but there is reason to believe that information about mice might be useful for aging research, this information is included. The purpose of the review is to acquaint gerontologists with the availability of genetically defined animal models for aging research, to present what is known about these models, and to suggest areas of research which could profit from more attention.

Avoidance learning, behavior genetics, and aging: a critical review and comment on methodology

Animal models of human aging problems are potentially of enormous value to gerontological research. Models of behavioral problems have not often lived up to their promise. This review examines one such model system, avoidance learning in aging rodents. This model system has become increasingly popular among behavioral gerontologists, yet it has not provided the unambiguous answers to experimental questions which investigators expected. Our effort has been to determine why the system has failed, and to provide useful suggestions for future research. At the same time we have tried to provide a comprehensive review of the relevant literature and to assess the strengths and weaknesses of studies which have been conducted in the last two decades.

Effects of age and genotype on acquisition of an active avoidance response in mice

Two experiments were conducted in which inbred C57BL/6J and DBA/2J mice were trained in an active avoidance jump-up task under distributed practice conditions at a variety of ages comprising a large part of their life-span. DBA/2J mice were found to be basically an escaping strain and exhibited little change in behavior as a function of age. C57BL/6J mice developed consistent avoidance behavior when training was initiated at 31-36 days of age. Avoidance behavior appeared to reach a peak in the 45-day-old group and progressively decreased in 145- and 560-day-old groups. Increased footshock intensity in old DBA/2J mice enhanced escape responding without increasing avoidance responding. Increased footshock intensity in old C57BL/6J mice enhanced avoidance responding.

Genetic analysis of active avoidance performance in mice

Mice of two inbred strains, C57BL/6J and DBA/2J, and the F1 hybrid of a cross between them were trained in an active avoidance jump-up task under distributed practice conditions. Significant differences in the performance of mice of the two strains were observed, with relatively poor performance by DBA/2J mice and relatively good performance by C57BL/6 mice. The performance of F1 hybrid mice did not differ significantly from DBA/2J mice. Crosses were made to produce segregating generations of mice. Their performance supported a single-locus model of inheritance for active avoidance jump-up behavior. Under these experimental conditions the dominant allelle (Aapd) was associated with poor performance while homozygosity for the recessive allele (Aapb) was associated with superior performance.

Behavioral studies using genetically defined mice. A bibliography

References in this bibliography have been selected from the Subject-Strain Bibliography of Inbred Strains of Mice, maintained at The Jackson Laboratory, which attempts to include all published papers dealing with specific inbred strains of mice, named genes in mice, or named transplantable tumors. We have selected all references which appear to be of behavioral interest, including reports of the effects of neurological mutations, but have omitted genetic studies conducted with these mutants. Studies using "white", "Swiss", or undesignated mice are not included. This bibliography covers literature published from 1922 through late 1973. The authors would like to be informed of omissions, and to receive reprints of omitted papers. The bibliography is divided into three sections. The first section includes all references in which a behavioral measure appears to be the variable of primary interest. This section is divided into 16 behavioral categories: activity, aggression, audiogenic seizures, communication, emotionality, feeding, learning, maternal, memory, psychomotor, regulation, reproduction, biorhythms, sensation, social, and miscellaneous. References are assigned to a category on the basis of their apparent emphasis. The second section includes all references in which the effects of a treatment on behavior appear to be the variables of primary interest. This section is divided into nine treatment categories: age, alcohol, central nervous system, mutations, neonatal and teratogenic, population size, pharmacological agents, genetic selection, and miscellaneous. Where multiple treatments were used, references are assigned to the category of the most important treatment. The third section contains reviews and theoretical references. Each item in the bibliography is assigned to a category in one of the three sections and given a reference number. At the end of each category is a list of the reference numbers from other categories which contain information pertinent to that category. References are arranged alphabetically within each category.

Open-field behavior in aging inbred mice

Open-field activity levels of young (2- to 6-month-old) and older (12- to 30-month-old) C57BL/6J and DBA/2J mice were assessed in two experiments conducted in separate laboratories. A large decrement in activity level was observed with advancing age in mice of both genotypes. The environment in which the subjects were maintained and tested also appeared to be a major contributor to behavioral variability in the openfield.

Social olfaction: a review of the role of olfaction in a variety of animal behaviors

Behavioral olfactory experiments were reviewed, relating the behavioral effects of pheromones to the psychophysical work in olfaction. Short descriptions of various experiments were used to show the importance of olfaction to the social behavior of animals by tracing the history of the experimental evidence and viewing the behavioral data pertaining to the discharge of pheromones and their effects and to look at the psychophysical evidence for olfactory acuity and the behavioral implications for the role of the physiological structures in olfaction.

"Fear communication" via odor in inbred mice

The application of a treatment to one group of Ss had effects upon another group of Ss not so treated. The effects, largely upon resistance to extinction, were probably mediated by odor. The data suggested that Ss exhibited conditioned and unconditioned responses to odors left by other Ss.

Barometric pressure fluctuations: effects on the activity of laboratory mice

Fluctuations in naturally occurring levels of barometric pressure appear to be an important determinant of activity in laboratory mice. In three experiments, activity was higher after increases in barometric pressure than it was after decreases. When the barometric pressure remained relatively stable, intermediate levels of activity were observed.

Retrograde amnesia in two strains of mice

The administration of electroconvulsive shock after foot shock in a passive avoidance learning situation produced retrograde amnesia if electroconvulsive shock occurred within 20 sec. of the foot shock. If the time interval between foot shock and electroconvulsive shock was 20 sec. or longer, retrograde amnesia was not observed. No behavioral differences were observed between two inbred strains of mice, the DBA/2J and the C57BL/6J.

The effects of electroconvulsive shock on the action of a reinforcing stimulus

Three experiments sought to evaluate the effect of electroconvulsive shock on the action of a reinforcing stimulus. In all experiments behavior was maintained on a 2 min variable interval schedule for food reinforcement. Foot shock at the termination of a buzzer stimulus served as the reinforcing stimulus for conditioned suppression during the ensuing buzzer interval. Omission of foot shock at the termination of the buzzer stimulus was followed by normal responding (no conditioned suppression) during the next buzzer interval. In Exp I electroconvulsive shock followed foot shock at varying time intervals. In the first subsidiary experiment electroconvulsive shock followed an unreinforced buzzer stimulus at varying time intervals. In the second subsidiary experiment electroconvulsive shock followed foot shock at varying time intervals and an additional buzzer stimulus was sounded between the termination of foot shock and the onset of electroconvulsive shock. These three experiments demonstrated that electroconvulsive shock invariably abolished the effects of the reinforcing stimulus if it followed conditioning by no more than 10.0 sec and never had an effect if it followed conditioning by 12.5 sec or more; electroconvulsive shock was not acting as a reinforcing stimulus in this situation.