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Biomedical subjects

C A Cornwell-Jones

Publications and source records attributed to C A Cornwell-Jones.

12 recordsLinked to original sources
PubMed1992

Housing influences exploration and social interaction of control and DSP-4-treated rats.

Exploratory behavior and social interaction were investigated in rats that were reared in different social environments following neonatal injection with either water vehicle or the norepinephrine neurotoxin, DSP-4. At weaning, they were placed in a familiar or novel bedding type and were housed in either vehicle control-only, DSP-4-only, or mixed vehicle control and DSP-4 groups for 10 days. They were then observed in three different situations: the home cage, the cage of an unfamiliar rat, and an open field. Compared to rats housed in vehicle control-only or DSP-4-only groups, rats housed in mixed DSP-4 and vehicle control groups showed elevated exploration behavior in the home cage. Also, rats housed in mixed groups in the familiar bedding, but not the novel one, showed abnormally low levels of rearing in an open field test and reduced social interaction with unfamiliar rats. The implications of these results for a new animal model of anxiety are discussed.

Adrenergic Agents↗
PubMed1990

Norepinephrine depletion reduces the effects of social and olfactory experience.

Control juvenile rats adapted normally to a new home-cage bedding odor if they were caged with rats neonatally treated with 6-hydroxydopa, but not DSP-4. Neither social nor olfactory experience influenced preferences of NE-depleted rats. In some forebrain regions of controls caged with DSP-4 rats, monoamine concentrations were depressed and a metabolite elevated, suggesting the situation was stressful. DSP-4 treatment decreased the effect of footshock on hippocampal cholinergic activity, implying that NE depletion reduced sensitivity to stress. Thus, norepinephrine may modulate the biobehavioral effects of the postweaning olfactory and social environment.

Adaptation, Physiological↗
PubMed1989

Neonatal 6-hydroxydopa, but not DSP-4, elevates brainstem monoamines and impairs inhibitory avoidance learning in developing rats.

The involvement of brain monoamines in learning and memory in developing rats was studied by comparing the effects of 3 different noradrenergic neurotoxin treatments. Two experimental groups of male Sprague-Dawley rat pups were injected systemically with 50 micrograms/g of N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4) either on the day of birth or on postnatal days 17-18. Rats in the third experimental group were injected systemically with 60 micrograms/g of 6-hydroxydopa (6-OHDOPA) on postnatal days 0 and 2. Control littermates received vehicle. The animals were trained on an inhibitory avoidance task on postnatal days 27-29 and tested for retention 24 h later. The drug treatments produced comparable depletion of norepinephrine in the hippocampus and frontal cortex. 6-OHDOPA, but neither DSP-4 treatment, significantly elevated brainstem concentrations of norepinephrine and serotonin. In addition, 6-OHDOPA, but not DSP-4, significantly impaired retention of the inhibitory avoidance task. The impairment did not reflect insensitivity to the footshock used in training: both neonatal drug treatments tended to lower, not raise, footshock thresholds, as measured by a flinch test. High affinity choline uptake was not affected by either neonatal drug treatment in any of the brain areas examined. Thus, the 6-OHDOPA-induced behavioral deficit did not involve altered acetylcholine function. The results implicate brainstem monoamines in the modulation of learning and memory during development.

Animals↗
PubMed1988

Early experience influences adult retention of aversively motivated tasks in normal, but not DSP4-treated rats.

Sprague-Dawley rat pups were injected with DSP4 or water within 48 hr of birth and tested as adults in an inhibitory avoidance task and in a Y-maze discrimination reversal task. Half of the animals were also tested as juveniles during postnatal weeks 4-5, in tasks assessing odor preferences and general investigatory behavior. Controls, but not drug-treated adults, which received the juvenile testing, showed significantly better retention on both tasks than either controls or drug-treated animals not tested as juveniles. Neonatal DSP4 significantly reduced norepinephrine concentrations in the hippocampus and frontal cortex, but not the heart. The results suggest that central norepinephrine may modulate the effects of early experience on adult learning.

Animals↗
PubMed1988

DSP4, a noradrenergic neurotoxin, impairs male rats' attraction to conspecific odors.

Olfactory investigation was examined in male Sprague-Dawley rats injected with 50 mg/kg of the noradrenergic neurotoxin, DSP4, 10 days before testing. In a two-choice preference test, the odor of pine shavings from the nest of a female and her litter attracted sexually experienced control males, but not drug-treated males. Further, odors from anesthetized females increased the mean number of entries made by control males, but not drug-treated males, into a cage containing pups' nest shavings. Combining a novel odor with nest shavings significantly reduced the number of entries made by both groups of males. Drug treatment decreased norepinephrine (NE) levels by 66, 62, and 68% in the olfactory cortex, olfactory bulb, and frontal cortex, respectively. Dopamine concentrations were not significantly affected. NE concentrations in the heart, and serotonin levels in the olfactory bulb, were moderately depleted (by 37 and 40%, respectively). The results support the view that central NE modulates systems regulating attraction to conspecific odors in male rats.

Adrenergic Fibers↗
PubMed1983

Neonatal 6-hydroxydopa alters conspecific odor investigation by male rats.

Odor-guided behavior was examined in male rats injected at birth and 48 h later with either the catecholaminergic neurotoxin 6-hydroxydopamine (60 micrograms/g, i.p.) or vehicle. In odor preference tests administered 8 or 74 days postnatally, drug-treated animals avoided novel odors which were neutral for controls and showed reduced preference for conspecific nest odors. In emergence tests administered 73-75 days postnatally, odors from an anesthetized female reduced approach latency and increased investigation of familiar conspecific odors for control but not drug-treated males. Neonatal drug treatment decreased adult olfactory cortex norepinephrine (NE) levels by 50%, but did not significantly influence either cardiac NE or olfactory cortex dopamine. The results imply that brain NE facilitates attraction to familiar conspecific odors.

Animals↗
PubMed1982

Olfactory development in gerbil pups.

In a 2-choice situation, Mongolian gerbil pups show a preference for home-cage bedding oder that appears during the 2nd postnatal week and is consistently high between Days 8 and 14. Pups show responses to certain nonanimal odors as early as Day 4, indicating that the motor capacity to orient to odors precedes in emergency of nest odor preference. Increases in pups' nest odor preference appear to parallel increases in the frequency of maternal nest-building, an activity which can eject pups from the nest. This coincidence suggests that olfaction helps displaced pups to return to their nests.

Aging↗
PubMed1981

Conspecific odor preferences of male albino rats are reversed by intracerebral 6-hydroxydopamine.

The odor of pine shavings from the nest of a female and her litter attracted sexually experienced male Sprague-Dawley rats tested in a two-choice situation. The preference persisted after surgery in controls treated with bilateral intracerebral injections of saline-ascorbic vehicle into the vicinity of the ascending noradrenergic bundle. In contrast, 7 out of 8 animals receiving bilateral injections of the neurotoxin 6-hydroxydopamine (6-OHDA), preferred the odor of clean pine to pine nest odor after surgery, indicating preference reversal. 6-hydroxydopamine also reduced olfactory cortex norepinephrine (NE) concentrations by 85%. Pretreatment with intracerebral injection of amphetamine, a catecholamine uptake inhibitor and releaser, prevented 6-OHDA-induced preference reversal in 7 out of 8 animals and limited NE reduction to 38% of concentrations measured in amphetamine-pretreated vehicle-injected controls. The data implicate central NE in the modulation of responses to conspecific odors.

Amphetamine↗
PubMed1980

Castration decreases olfactory bulb norepinephrine in male rats but not hamsters.

Norepinephrine (NE) concentrations were measured in the olfactory bulbs and olfactory cortex of male albino rats and golden hamsters sacrificed 13-16 days after castration or sham surgery. Castration significantly decreased NE concentrations in the olfactory bulbs of rats but not hamsters. Castration had no significant influence on NE levels in the olfactory cortex of either species. Regional brain weights were not influenced by surgery, and previous olfactory exposure had no significant effect on any variable measured. The decrease in rat olfactory bulb NE levels may be involved in castration-induced changes in preferences for conspecific odors.

Animals↗