ABSTRACT
We have adapted to mice a holeboard-learning task, which allows simultaneous assessment of spatial working and reference-memory performance. The holeboard apparatus consists of an open-field chamber with a 16-hole floor insert. Across trials, animals have to learn that the same four holes of 16 are always baited. Here, we show that C57BL/6 mice readily acquire this task within 4 days when submitted to six trials per day or within 8 days when submitted to only four trials per day. We also show that C57BL/6, Swiss-Webster, CD-1 and DBA/2 mice acquire this task similarly, despite the fact that some differences could be observed in measures of exploratory activity during habituation and training. Moreover, the muscarinic antagonist scopolamine disrupts learning at doses of 0.1 and 1.0 mg/kg, although the highest dose appeared to have side-effects. Lastly, we found that amyloid precursor protein transgenic mice have a selective disruption in their working-memory performance only during reversal training (i.e. after a change in the configuration of the baited holes). Overall, our data indicate that this spatial learning task is well adapted to mice and will be useful to characterize spatial memory in various genetic or pharmacological mouse models.
Subject(s)
Amyloid beta-Protein Precursor/physiology , Discrimination Learning/physiology , Exploratory Behavior/physiology , Memory, Short-Term/physiology , Spatial Behavior/physiology , Amyloid beta-Protein Precursor/genetics , Analysis of Variance , Animals , Discrimination Learning/drug effects , Dose-Response Relationship, Drug , Exploratory Behavior/drug effects , Genetics, Behavioral/methods , Male , Memory, Short-Term/drug effects , Mice , Mice, Inbred C57BL , Mice, Inbred DBA , Mice, Transgenic , Muscarinic Antagonists/administration & dosage , Reversal Learning/drug effects , Reversal Learning/physiology , Scopolamine/administration & dosage , Species Specificity , Statistics, NonparametricABSTRACT
BACKGROUND: The alcohol deprivation effect (ADE) is a temporary increase in the voluntary intake of ethanol solutions following a period of alcohol deprivation. Multiple deprivations can prolong the expression of an ADE. This study examined the effects of initial deprivation length, concurrent exposure to multiple ethanol concentrations, and number of deprivation exposures on the magnitude and duration of the ADE in alcohol-preferring (P) rats. METHODS: Adult female P rats received 24-hr free-choice access to 10, 20, and 30% ethanol and water for 6 weeks. Rats were then randomly assigned to three groups; one group served as a nondeprived control, whereas the other two groups were initially deprived of ethanol for 2 or 8 weeks. The ethanol solutions were restored to both deprived groups for 2 weeks before the groups were deprived of ethanol for another 2 weeks. This cycle was repeated three times for a total of four deprivations. RESULTS: After the initial ethanol deprivation period, both deprived groups displayed a similar 2-fold increased ethanol intake (g/Kg/day) during the initial 24-hr period when ethanol was restored. Both deprived groups showed greater than 2-fold increases in intake of the 20 and 30% ethanol solutions after re-exposure. Ethanol consumption returned to baseline levels within 2 weeks, before the subsequent deprivation period. Multiple deprivations increased the magnitude of the ADE over that observed in the first deprivation during the initial 24-hr period of re-exposure and prolonged the duration of the ADE. In addition, repeated deprivations increased ethanol intake in the first 2-hr period of re-exposure and produced blood ethanol levels in excess of 150 mg/100 ml. CONCLUSIONS: Alterations in the reinforcing and/or aversive effects of alcohol occurred after a single prolonged deprivation and were enhanced with repeated deprivations.
Subject(s)
Ethanol/administration & dosage , Animals , Dose-Response Relationship, Drug , Drinking , Ethanol/blood , Female , Food Preferences , Rats , Reinforcement, Psychology , Self Administration , Solutions , Time FactorsABSTRACT
The anti-tumor effects of actinomycin D (Act D) and recombinant human tumor necrosis factor (TNF)-alpha have been studied on 4 established murine tumor cell lines: MmB16 melanoma, Lewis lung (LL/2) carcinoma, L1 sarcoma and L1210 leukemia. During short-term incubation (24 hr) Act D produced dose-dependent cytostatic/cytotoxic effects against MmB16, LL/2 and L1 tumor cells but did not reduce the viability of these cells even at high concentration (10 micrograms/ml), below a threshold of 30-60%. However, L1210 leukemic cells were highly susceptible to Act D, and no viable cells were detected in cultures incubated with 1 microgram/ml of Act D. TNF-alpha alone, when used under the same culture conditions, had only a negligible effect on all cell lines tested. However, the combination of this cytokine with Act D produced synergistic cytotoxic effects against MmB16, LL/2 and L1 cells but not against L1210 leukemia cells. In an in vivo model of regional therapy in which tumor-bearing mice were treated with Act D and TNF-alpha, a correlation with in vitro results was observed. In mice bearing MmB16 melanoma, LL/2 carcinoma and L1 sarcoma, the most potent anti-tumor effects were observed in mice treated with Act D and TNF-alpha together. This treatment led to a delay of tumor growth and induced complete tumor regression in some cases. On the contrary, TNF-alpha did not enhance the effect of Act D in mice injected with L1210 leukemia cells. Our results show that TNF-alpha can potentiate the anti-tumor effects of Act D against tumors weakly susceptible to Act D and may be a useful adjuvant to chemotherapy in the local treatment of neoplasia.
Subject(s)
Antibiotics, Antineoplastic/toxicity , Dactinomycin/toxicity , Neoplasms, Experimental/drug therapy , Tumor Necrosis Factor-alpha/toxicity , Animals , Antibiotics, Antineoplastic/therapeutic use , Cell Line , Dactinomycin/therapeutic use , Drug Synergism , Leukemia L1210/drug therapy , Lung Neoplasms/drug therapy , Melanoma, Experimental/drug therapy , Mice , Mice, Inbred BALB C , Mice, Inbred C57BL , Mice, Inbred DBA , Neoplasms, Experimental/pathology , Sarcoma, Experimental/drug therapy , Time Factors , Tumor Cells, Cultured , Tumor Necrosis Factor-alpha/therapeutic useABSTRACT
Granulocyte-macrophage colony-stimulating factor (GM-CSF) has not been found to exert any influence on the proliferation of Lewis lung carcinoma (LLC) cells in vitro. Nevertheless, when administered intraperitoneally, GM-CSF accelerated the growth of subcutaneously growing LLC in mice.
Subject(s)
Carcinoma, Lewis Lung/pathology , Granulocyte-Macrophage Colony-Stimulating Factor/pharmacology , Animals , Cell Division/drug effects , Female , Mice , Mice, Inbred C57BL , Mice, Inbred DBAABSTRACT
The efficacy of combination treatment with actinomycin D (Act D), recombinant human tumor necrosis factor-alpha (TNF-alpha), and recombinant murine interferon-gamma (IFN-gamma) was examined on established MmB16 melanoma in mice. TNF-alpha alone had marginal effect in vitro on melanoma cells. However, when this cytokine was combined with either Act D or IFN-gamma, synergistic cytostatic/cytotoxic effects were observed. The highest cytotoxicity was demonstrated in cultures of melanoma cells in which all three agents together were added. In mice inoculated with 10(6) melanoma cells (into the footpad of the hind limb) and treated locally with Act D, TNF-alpha and IFN-gamma, beneficial therapeutic effects were found. When initiated 1 week after tumor cell inoculation, the 7-day treatment with all these agents administered together at daily doses: 0.2 microgram (Act D), 1 microgram (TNF-alpha), and 200 U (IFN-gamma) resulted in a significant delay of tumor progression in comparison to the therapy that included either Act D alone or TNF-alpha in combination with IFN-gamma. Side effects of such a treatment, both local and systemic, were negligible. The results of this study demonstrate that combination of regional chemotherapy (actinomycin D) and immunotherapy (TNF-alpha/IFN-gamma) may display higher efficacy than either treatment alone and may increase therapeutic index without augmenting toxic effects.
Subject(s)
Antineoplastic Combined Chemotherapy Protocols/therapeutic use , Dactinomycin/administration & dosage , Interferon-gamma/administration & dosage , Melanoma, Experimental/drug therapy , Tumor Necrosis Factor-alpha/administration & dosage , Animals , Cell Survival/drug effects , Dose-Response Relationship, Drug , Humans , Male , Mice , Mice, Inbred C57BL , Mice, Inbred DBA , Recombinant ProteinsABSTRACT
The efficacy of systemic infusion of recombinant human macrophage-colony-stimulating factor (M-CSF) in combination with local treatment with human recombinant tumor necrosis factor (TNF) alpha and mouse recombinant interferon (IFN) gamma was studied in vivo on a subclone of B16 melanoma (MmB16) in mice. Short-term intravenous administration of M-CSF at a dose of 10(6) units daily had no antitumor effect in vivo. Similarly, local treatment of tumor with TNF alpha (5 micrograms daily) did not produce any therapeutic effect. However, simultaneous administration of the same dose of TNF alpha with IFN gamma (1000 units daily) resulted in a synergistic effects manifested by the retardation of tumor growth. Addition of systemic infusion of M-CSF to the local therapy with TNF alpha and IFN gamma induced further augmentation of antitumor efficacy and delayed progression of MmB16 melanoma. The strengthened antitumor effect of combination therapy including M-CSF, TNF alpha and IFN gamma was most probably due to the increased release of monocytes from the bone marrow, their recruitment into the site of tumor growth and subsequent local stimulation of their antitumor activity.
