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G Ellison

Publications and source records attributed to G Ellison.

At least 73 records · Page 4Linked to original sources
PubMed1982

Low-level continuous amphetamine administration selectively increases alcohol consumption.

Rats dramatically increased alcohol preference following the subcutaneous implantation of slow-release d-amphetamine pellets, so long as access to ethanol was withheld during the initial 6 days after pellet implantation. This increased ethanol preference was not due to a conditioned flavor aversion, nor to increased caloric intake, nor to alcohol deprivation. d-Amphetamine must be administered in a continuous fashion in order to obtain this effect, for daily injections of the same amount of the drug did not increase ethanol intake. This increased ethanol preference is interpreted as self-medication. This effect may provide a new animal model for the tension-reduction theory of ethanol intake.

Alcohol Drinking↗
PubMed1982

Cytotoxic activity of peripheral blood and cerebrospinal fluid lymphocytes from patients with multiple sclerosis and other neurological diseases. Analysis at the single cell level using morphological and surface marker phenotype criteria.

The large granular lymphocyte (LGL) has been identified in normal individuals' MNC population as the NK-K cell (Ault and Weiner 1978; Timonen et al. 1981); it bears the OKM1 surface antigen (Breard et al. 1981; Fast et al. 1981) and while negative for T cell antigens OKT4 and OKT8, is a low avidity E-rosette forming cell. However, in a unfractionated nylon wool passed peripheral blood lymphocyte (NWP PBL) population, we show that not more than 50% of KN activity in normal or OND control NWP PBL and 30% NK activity in MS NWP PBL can be attributed to this cell. Nevertheless, 100% of control K cell activity and 50% of MS K cell activity can be mediated by an LGL. MS patients have normal proportions of LGLs in their NWP PBL. The proportion of LGLs in CSF of MS and OND patients is too low to account for the number of CSF K cells. While in control NWP PBLs, the LGLs are OKM1+ and mediate NK and ADCC, in MS the LGL NK effectors are probably different from LGL-K cell effectors. In MS both populations include effector cells with cell surface antigens. Thus, the OKM1+ LGL characteristics may not be used in analysis of NK and K cells in multiple sclerosis.

Acute Disease↗
PubMed1982

Alterations in the stages of continuous amphetamine intoxication produced by lesions of locus coeruleus and substantia nigra.

1. Slow-release silicone pellets containing d-amphetamine base were implanted subcutaneously in rats 20 days following radio-frequency lesions of the locus coeruleus (LC), substantia nigra (SN), or control operations. 2. LC-lesioned rats exhibited enhanced motor stereotypies soon after implantation, while SN-lesioned animals showed increased locomotion but decreased stereotypy and anorexia. 3. The later behavioral stages of continuous amphetamine intoxication were attenuated in both lesioned groups as controls then entered the most intense stereotypy, showed the greatest withdrawal to the burrows, and maximally exhibited the increase in socially disruptive behaviors which appear following four days of constant amphetamine intoxication. 4. The integrity of both dopaminergic and noradrenergic systems was necessary for the full expression of the late stages of this animal model of amphetamine psychosis.

Amphetamine↗
PubMed1981

Opposed stages of continuous amphetamine administration: parallel alterations in motor stereotypies and in vivo spiroperidol accumulation.

Rats pretreated with different regimens of chronic d-amphetamine (d-Amp) administration were injected 24 h after cessation of chronic d-Amp with either d-Amp (to test the degree to which it now elicited motor stereotypies) or with [3H]spiroperidol (to study in vivo accumulation in 7 brain regions). Rats pretreated with 28 daily injections of d-Amp subsequently evidenced heightened stereotypies to d-Amp whereas other rats pretreated with the same amount of d-Amp for 28 days using slow-release pellets showed decreased stereotypies to d-Amp. In neither of these chronic groups was spiroperidol accumulation altered. But the administration of d-Amp continuously over briefer periods induced large and phasic alterations in both d-Amp induced stereotypes and in spiroperidol accumulation. Rats given continuous d-Amp for 24 h, allowed a 24 h drug-free period, and then injected evidenced a large potentiation of both stereotypies and in vivo accumulation of spiroperidol in the caudate nucleus, whereas after 5 days of continuous d-Amp administration rats showed attenuated stereotypies and decreased [3H]spiroperidol accumulation in the caudate, accumbens, and substantia nigra. These results imply that brief periods of continuous d-Amp administration produce large and phasic changes in dopamine systems.

Animals↗
PubMed1981

The regional distribution of d-amphetamine and local glucose utilization in rat brain during continuous amphetamine administration.

The distribution of radioactivity following administration of either [3H]d-ampetamine or [3H]2-deoxy-d-glucose was examined by scintillation counting of 22 microdissected brain regions from rats pretreated with either acute or continuous amphetamine, or continuously administered labeled d-amphetamine. Animals continuously administered drug were sacrificed in behaviorally distinct stages of the continuous amphetamine syndrome, a potential animal model of amphetamine psychosis. Both isotopes were heterogeneously distributed within brain, and their distributions were differentially affected by acute or continuous amphetamine regimens. While the distribution of either isotope in naive rats was characterized by greatest concentrations of counts in rostral rather than caudal regions, and grey-matter rather than white-matter structures, continuous amphetamine administration resulted in progressively increased retention of amphetamine by mesolimbic but not nigrostriatal brain regions; this was accompanied by locally enhanced levels of glucose utilization. This effect was predominantly localized in the nucleus accumbens, which exhibited the greatest retention of amphetamine and greatest relative increase in glucose utilization of any region studied during that stage of the continuous amphetamine syndrome thought to best model amphetamine psychosis. Alterations in amphetamine distribution and local levels of neural activity may reflect a change in the principal locus of control of amphetamine effects within brain as animals progress through the stages of the continuous amphetamine syndrome.

Amphetamine↗
PubMed1981

A silicone delivery system for producing binge and continuous ethanol intoxication in rats.

A silicone delivery system for administering large quantities of ethanol (ETOH) to rats is described. When implanted subcutaneously and filled with 95% ETOH (v/v), lethal quantities can be administered within 5 days. Two different models are described: a rapid release thin-walled silicone pillow which can be filled with 95% ETOH for 3 hours daily so as to induce binge-like, transient high blood ETOH levels and motor impairment, and a thicker pillow which can be filled daily with 84% ETOH (v/v) so as to produce continuous ETOH administration. When different groups of rats administered similar amounts of ETOH using these two different regimens were compared, it was found that caloric intake (food + ETOH) and body weight were reduced in the Binge group whereas the Continuous group gained weight although their total caloric intake was similar to Controls. This delivery system can deliver appreciable amounts of ETOH to rats in the absence of gustatory stimulation and in two intake patterns which have been reported to occur in alcoholics.

Alcoholic Intoxication↗
PubMed1981

The regional distribution of amphetamine in rat brain is altered by dosage and by prior exposure to the drug.

Rats were sacrificed 30 min after an i.p. injection of tritium-labeled d-amphetamine and the regional distribution of radioactivity was determined in 22 discreet brain regions. Amphetamine accumulation was greatest in rostral brain areas such as cortex ad forebrain and least in brainstem and white matter. Sensory regions (occipital cortex and thalamus) retained more label than did nonsensory regions (entorhinal cortex and hypothalamus). The regional distribution of d-amphetamine in drug naive animals was altered by variations in carrier dosage with heightened drug accumulation in occipital cortex and thalamus at a 1.5 mg/kg carrier dose and enhanced accumulation in the hippocampus and amygdala with a 5.0 mg/kg carrier dose. Increased amphetamine retention by dopamine-rich regions, such as the caudate, was observed in rats to which 28 daily injections of the drug had been administered previously. Thus, the regional distribution of d-amphetamine in rat brain is altered by variations in carrier dosage and previous drug experience.

Animals↗
PubMed1980

Decreased spiroperidol and LSD binding in rat brain after continuous amphetamine.

Rats were implanted with a silicone tubing pellet continuously releasing amphetamine base for several days. After five days of this treatment specific binding of spiroperidol (dopamine receptors) and LSD (serotonin receptors) was decreased in the corpus striatum and frontal cortex. In the striatum the number of dopamine receptors was decreased while the affinity was unchanged. These results indicate that dopamine and serotonin receptors can be regulated by the release of their own neurotransmitter.

Amphetamine↗
PubMed1980

Following several days of continuous administration d-amphetamine acquires hallucinogenlike properties.

Rats injected with LSD or mescaline show the behavioral syndrome which has been previously reported following injections of hallucinogens in higher mammals: limb flicks and whole body shakes. Although these behaviors are not elicited by acute injections of amphetamine, they are present in rats which have been pretreated for 108 h with a slow-release amphetamine pellet, given a 12 h rest period, and then injected with d-amphetamine. Such pellet-pretreated animals also groom their body surface excessively. We propose that this novel syndrome which follows continuous amphetamine administration can serve as an animal model of the type of amphetamine psychosis that is produced by a similar drug regimen in humans.

Animals↗
PubMed1980

Cumulative alterations in rat behavior during continuous administration of LSD or mescaline: absence of tolerance?

Male hooded rats were observed for 6 days following implantation with slow-release subcutaneous pellets containing LSD, mescaline, or control vehicle solution. In animals housed in isolation cages, continuous hallucinogen administration resulted in a gradual increase in head twitches and catatonic postures which peaked 3--4 days after pellet implantation and then declined. In animals housed in social colonies, there were also delayed increases in behavior following hallucinogen-pellet implantation, but these principally involved social behaviors such as fighting by mescaline-treated animals and social grooming by LSD-treated animals. This finding of gradual and cumulative effects of continuous hallucinogen administration contrasts with the usual finding of a rapid tolerance to hallucinogens following repeated injections.

Animals↗
PubMed1978

Long-term changes in dopaminergic innervation of caudate nucleus after continuous amphetamine administration.

Silicone pellets containing d-amphetamine base were implanted subcutaneously in rats. These pellets release amphetamine continuously for at least 10 days. Several days after implantation, swollen dopamine axons concomitant with large decreases in tyrosine hydroxylase activity were observed in the caudate nucleus. Decreased tyrosine hydroxylase activity was still present 110 days after pellet removal in the caudate but not in several other brain regions, nor in the caudate of rats injected with an equivalent amount of amphetamine in daily injections. This implies that continuous amphetamine administration has a selective neurotoxic effect on dopamine terminals in the caudate.

Animals↗
PubMed1978

Stages of constant amphetamine intoxication: delayed appearance of abnormal social behaviors in rat colonies.

Rats in colonies were observed for 7 days after half of them were implanted with slow-release silicone pellets containing d-amphetamine base. The drug-implanted animals were initially hyperactive and exploratory, but this gradually evolved over the next 24 h into motor stereotypies of an increasingly more circumscribed nature. On the 4th day after amphetamine implantation they transiently withdrew to the burrows area; thereafter they were characterized by heightened startle responses and increased social behaviors such as fighting and fleeing. During the last phase some of the drug-implanted animals tended to focus their fighting behaviors on one other drug-implanted animal. This late phase of constant amphetamine intoxication in rats has a number of similarities to amphetamine psychosis in humans, and can serve as a useful animal model for the study of its biochemical correlates.

Animals↗
PubMed1978

Stages of recovery from central norepinephrine lesions in enriched and impoverished environments: a behavioral and biochemical study.

Adult rats were injected intraventricularly with 6-OHDA and allowed to recover for varying time periods in either an enriched colony environment or in isolation cages. When tested behaviorally in a novel environment, isolated animals showed a cyclical recovery pattern, with behavioral changes at 14 days after lesioning which were different from those seen at 2 and 45 days after lesioning. In contrast, animals housed in a colony environment showed progressive improvement and better recovery than isolates. Biochemical studies of uptake of H3NE and histofluorescence indicated that colony housed animals had enrichment effects (higher cortical NE uptake), but they were also more susceptible to 6-OHDA and did not recover well from the lesions. Isolated animals showed somewhat better recovery of NE uptake following 6-OHDA injections, especially in cortex. Because behavioral recovery from 6-OHDA was dissociated from biochemical indicators of recovery in NE circuitry, these results imply that brain systems other than NE were primarily responsible for the enhanced behavioral recovery which occurs in enriched environments.

Animals↗