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Biomedical subjects

C A Hardy

Publications and source records attributed to C A Hardy.

5 recordsLinked to original sources
PubMed1990

Altered T-lymphocyte response following aggressive encounters in mice.

Intermale aggression is a natural form of psychosocial stress that can alter a variety of physiological functions, including immune function. In Experiment 1, daily fighting between pairs of previously isolated male mice differentially altered immunological measures of T-cell responsiveness in dominant and submissive animals. Submissive mice had lower T-cell proliferation and IL-2 production, when compared to dominant, nonfought, or witness mice. Since the fighting behavior often results in wounding of the submissive animal, Experiment 2 used a relatively nonaggressive test to determine whether the immunological differences between dominant and submissive mice were due to wounding or due to the psychosocial state of dominance. Dominant mice had elevated T-cell proliferation and IL-2 production when compared to the other treatment groups. Therefore, it appears that in dominant/submissive pairs of mice a severe physical stress, such as intense fighting, influences the immune system in a different manner than psychological or mild aggressive encounters.

Aggression↗
PubMed1987

Age- and sex-related induction of excessive grooming and "wet-dog" shakes by the codeinone RX 336-M in the rat.

Peripheral administration of the dihydrocodeinone RX 336-M (6 mg/kg) stimulated vigorous "wet-dog" shakes and excessive grooming in young drug-naive rats. The effects of RX 336-M were greater in younger than in older animals of both sexes, and were greater in 39-day-old male rats than in female rats of the same age. In a second experiment, female rats were pretreated with testosterone benzoate (1 mg/kg/day) for 1 week prior to testing the effects of RX 336-M at 39 days of age. The sex hormone pretreatment enhanced the ability to RX 336-M to induce "wet-dog" shakes and excessive grooming in female rats. The results suggest that both sex- and hormone-dependent developmental status are critical in the display of the so-called "quasi-morphine withdrawal syndrome." The results imply, and are consistent with previous studies which suggest, that different neural mechanisms underlie the behavioral responses induced by ACTH and RX 336-M.

Age Factors↗
PubMed1985

The progression of behavioral and pathological effects of the parasite Toxocara canis in the mouse.

Toxocara canis, the parasitic roundworm of the dog may infect aberrant hosts including mice and humans. The present study examined the behavioral and pathological changes at each of three postintubation periods (Period 1: 8-10 days, 2: 49-51 days, and 3: 84-86 days postintubation, respectively) in independent groups of mice intubated with 1000 eggs of T. canis. Eight-ten days after intubation Toxocara infected animals typically showed depressed levels of activity relative to saline-intubated controls. The scope and severity of behavioral changes were attenuated when different mice were tested 49-51 days after infection, and then became more severe when the third set of animals was tested 84-86 days after intubation. While brain pathology increased over the three periods, visceral organs showed marked pathology 8-10 days after intubation followed by a decrease in severity. These data suggest that Toxocara associated pathological changes in visceral organs and in the brain have behavioral consequences in mice. Given the similarity in migratory pathways of this parasite in rodents and humans, and the findings of T. canis larvae in human brain tissue, the results of this animal study may have implications concerning the possible etiology of behavioral disorders for children who have a known history of pica for dirt.

Animals↗