Individual and typological behavioral characteristics of CBA/CaLac mice.

Individual characteristics of higher nervous activity were studied in CBA/CaLac mice. The animals were divided into groups by the parameters of drinking response conditioning in a complex spatial environment. As distinct from bad learners, good learners exhibited higher orientation and exploratory activity in the open field, rapid adaptation, and low ability to retain the responses. Changes in conditioned reflex activity during neuroses were more pronounced in good learners.

Comparison of the behavior of the curly tail and CBA mouse on a neurologic scale.

ct/ct mice are a mutation of the CBA strain with a high incidence of spina bifida (SB). Because humans with SB can exhibit abnormal behavior, we compared ct/ct and CBA mice using a neurologic assessment tool. ct/ct mice are more active and engage in more climbing, and stereotypical and compulsive behavior. When stimulated during cage removal ct/ct mice react more vigorously. ct/ct mice react more vigorously to a novel stimulus, and will vigorously search for a stable surface during visual placement. In the open field ct/ct mice crossed more lines and reared more than CBA. ct/ct mice demonstrated deficient performance in a modified Morris water maze. No differences were noted for other behaviors tested. The results argue that the mutation that produces SB in ct/ct mice also alters brain structure or chemistry. This is consistent with the findings in humans where SB can produce a variety of behavioral anomalies, most notably hyperactivity, attentional disorders, learning disabilities, and developmental lags.

The cage design affects intermale aggression in small groups of male laboratory mice: strain specific consequences on social organization, and endocrine activations in two inbred strains (DBA/2J and CBA/J).

Effects of the enrichment of conventional laboratory housing cages with an additional labyrinth on intermale aggression, social organization, and activations of the pituitary-adrenocortical and sympathetic-adrenomedullary neuroendocrine subsystems are compared between adult male DBA/2J and CBA/J mice, differing genetically in their intermale aggression. Mice of both strains were kept three per cage for six weeks either in standard laboratory cages (SC) or in enriched cages (EC). Intermale aggression against a strange intruder and between cagemates was monitored once a week within each group. Dominance relations were derived from the distribution of attacks within a group. Plasma corticosterone titers (PCT) and activities of the tyrosinehydroxylase (TH) and phenylethanolamine N-methyltransferase (PNMT) were determined for each mouse at the end of the study. The main findings were: 1. Intermale aggression increased in both strains in groups kept in EC. 2. In the more aggressive DBA/2J the pattern of social organization shifted from groups with a single permanent dominant mouse in SC to groups with a frequently changing dominant mouse in EC. 3. In CBA interchanges of the dominant mouse was prevailing and did not differ between the two housing conditions. 4. In DBA/2J mice PCT were significantly elevated in EC. 5. In CBA/J mice activities of TH and PNMT were significantly elevated in EC. 6. Body weight gain was significantly delayed in mice kept in EC in both strains. Findings revealed strainspecific environmental effects on both social organization and endocrine states. The PCT increase obtained only in DBA/2J indicate that alterations of the social relations between cagemates are more likely to induce states of stress than an increase in intermale aggression alone.

Immune responses in male mice with aggressive and submissive behavior patterns: strain differences.

Immune responses in two strains of male mice with aggressive and submissive behavior patterns was studied. In aggressive CBA males immunized on the 10th day of agonistic confrontations with submissive partners, greater numbers of plaque-forming cells (PFC) and rosette-forming cells (RFC) were noted compared to control mice. Unlike the CBA strain, both PFC and RFC levels in aggressive C57BL males did not increase, but both PFC and RFC numbers decreased in submissive animals.