ABSTRACT
Twenty brother-sister pairs of mice were randomly selected from a genetically heterogeneous population of mice to begin a schedule of inbreeding that lasted for six generations (F = 0 to F = .732). We examined a number of indices of reproductive behavior and found that all declined as a function of inbreeding. Specifically, there was a consistent decline in the number of fertile matings, in the number of offspring that survived to weaning, and in the weight of the pups at the time of weaning (21 days of age). We also examined a number of behaviors with the following results: there was a systematic increase in the number of trials required to learn an active avoidance task and a consistent decrease in the number of trials required to extinguish this habit. We observed a statistically significant difference in the retention of a passive avoidance habit, but these results were quite variable and not consistent across generations of inbreeding. Finally, we observed that inbreeding had little effect on measures of locomotor behavior.
Subject(s)
Behavior, Animal/physiology , Infertility/genetics , Mice, Inbred Strains/genetics , Animals , Avoidance Learning/physiology , Female , Litter Size , Male , Mice , Motor Activity/physiology , Phenotype , PregnancyABSTRACT
To explain the persistence of schizophrenia in human populations at relatively high and constant rates, it is proposed that the schizoid-paranoid personality (designated as the Odyssean personality) which characterizes so many nonpsychotic relatives of schizophrenics, represents a selective advantage. It is assumed that odyssean relatives carry the gene or genes predisposing to schizophrenia, but not in sufficient quantity for the development of the psychosis. It is suggested that because of their schizoid-paranoid out-look, Odysseans have an increased probability of contributing to the gene pool of succeeding generations since, in a world plagued by terror, strife, and war, they, rather than their trusting peers, are the ones more likely to survive long enough to ensure the survival of their progeny.
Subject(s)
Genes , Paranoid Disorders/genetics , Paranoid Personality Disorder/genetics , Schizoid Personality Disorder/genetics , Schizophrenia/genetics , Adaptation, Psychological , Adoption , Biological Evolution , Diseases in Twins , Genetics , Heterozygote , Humans , Interpersonal Relations , Schizophrenic Psychology , Social ConditionsABSTRACT
Data on eight generations of selective breeding for acoustic priming efficacy are reported. The realized heritability of this trait is approximately 0.2-0.3, indicating that the trait is determined in part by genetic factors. Animals selectively bred for acoustic priming do not differ in terms of first-trial (i.e., non-priming-induced) audiogenic seizures. These data suggest that acoustic priming and first-trial audiogenic seizures are controlled by different genetic mechanisms.
Subject(s)
Genes , Seizures/genetics , Acoustic Stimulation , Age Factors , Animals , Breeding , Female , Male , Mice , Noise , Seizures/etiology , Sex FactorsABSTRACT
Samples of mice from each of 6 inbred strains were tested for audiogenic and electroconvulsive seizures at 5 ages (14, 21, 28, 35, and 42 days). A moderately large within-strain correlation (.67) was found, indicating that developmental patterns of susceptibility to audiogenic and electroconvulsive seizures are similar within each strain. The finding of an even larger between-strain correlation (.91) indicated that strains which are highly susceptible to audiogenic seizures are also likely to be highly susceptible to electroconvulsive seizures. In a 2nd experiment, whole brain norepinephrine and serotonin were assayed in each of 5 inbred strains at 21 and 42 days of age. Results were consistent with the hypothesis that levels of these amines are inversely related to seizure susceptibility. Mice from strains which were susceptible to seizures at 21 days of age had significantly lower levels of norepinephrine and serotonin in brain than did 42-day-old, seizure-resistant animals.
Subject(s)
Disease Susceptibility , Mice, Inbred Strains/physiology , Seizures/etiology , Acoustic Stimulation , Age Factors , Animals , Brain Chemistry , Electroshock , Genotype , Mice , Mice, Inbred C57BL , Mice, Inbred DBA , Motor Activity/physiology , Norepinephrine/metabolism , Seizures/mortality , Serotonin/metabolism , Species SpecificityABSTRACT
The activities of catechol-O-methyl transferase (COMT), monoamine oxidase (MAO), and a methanol forming enzyme were studied in whole brain homogenates and in livers obtained from DBA/2J, C57B1/6J, and F1 hybrid mice. DBA/2J mice are extremely susceptible to audiogenic seizures, whereas C57B1/6J mice are resistant to sound-induced convulsions. C57B1/6J mice were found to have significantly higher brain levels of COMT, while MAO activities were not different in animals of these genotypes. No methanol forming activity was detected in animals of either strain. No differences were found in hepatic activities of either COMT or MAO. Pyrogallol was shown to protect DBA/2J animals against audiogenic seizures.