Correlation between Brain Weight and the Pattern of Behavior Changes in Response to Ethanol Injections in Laboratory Mice

The effects of ethanol injections on the F₂ offspring of the cross between large-brain (LB) and small-brain (SB) mouse strains selected for high and low relative brain weights, respectively, have been studied. The parental strains have significantly differed in brain weight for many generations. The effects of ethanol (2.4 g/kg) have been compared in four subpopulations of mice that differ pairwise in brain weight. One pair of subpopulations has been derived from the hybrid group and the other, from generation 22 of selection of the parental strains. The results of ANOVA have demonstrated that brain weight is related to the behavioral response to ethanol injections. The parameters of stereotyped behavior, which increased in after ethanol injections and reflected the decrease in exploratory activity, were different in mice with high and low relative brain weights. The pattern of behavioral changes after ethanol injections is the second (after increased learning ability) behavioral trait found to be correlated with brain weight.     

Genetically determined differences in ethanol sensitivity influenced by body temperature during intoxication

The present study investigated the importance of body temperature during intoxication in mediating differences between five inbred strains of mice (C57BL/6J; BALB/cJ; DBA/2J; A/HeJ; 129/J) in their acute sensitivity to the hypnotic effects of ethanol. Mice exposed to 22 degrees C after ethanol injection became hypothermic and exhibited statistically significant differences between strains in rectal temperatures at the return of the righting reflex (RORR), duration of loss of the righting reflex (LORR), and blood and brain ethanol concentrations at RORR. Exposure to 34 degrees C after injection offset ethanol-hypothermia and markedly reduced strain-related differences in rectal temperatures and blood and brain ethanol concentrations at RORR. Brain ethanol concentrations at RORR were significantly lower in C57, BALB, DBA and A/He mice exposed to 34 degrees C compared to mice exposed to 22 degrees C during intoxication suggesting that offsetting hypothermia increased ethanol sensitivity in these strains. Taken with previous in vitro studies, these results suggest that genetically determined differences in acute sensitivity to the behavioral effects of ethanol reflect differences in body temperature during intoxication as well as differences in sensitivity to the initial actions of ethanol at the cellular level.     

Motor behavior and brain enzymatic changes after acute lead intoxication on different strains of mice

Lead is a nonphysiological metal that has been implicated in toxic processes that affect several organ systems in humans and other animals. Although the brain generally has stronger protective mechanisms against toxic substances than other organs have, exposure to lead results in several neurophysiological and behavioral symptoms. The administration of a single injection (i.p.) of lead acetate in mice is a model of acute Pb2 + toxicity. In the present study, this model was used to explore the magnitude of the effect of different doses, time intervals and mice strains on several biobehavioral parameters. We investigated the effects of acute lead acetate administration on body and brain weight, brain lead acetate accumulation and specially, spontaneous locomotion and brain catalase activity. Lead acetate was injected i.p. in outbred (Swiss or CD1) and inbred (BALB/c, C57BL/J6 or DBA/2) mice at doses of 0, 50, 100, 150 or 200 mg/kg. At different time intervals following this acute treatment, several biochemical, physiological and behavioral responses were recorded. Results indicated that acute lead acetate has deleterious dose-dependent effects on brain and body weight. The effect on body weight in the present study was transient, although lead acetate was detected in neural tissues for several days after administration. Spontaneous locomotor activity only was reduced up until 24 hours. The effect of lead on body weight was strain-dependent, with Swiss mice showing greater resistance compared to the other strains. Total brain catalase activity in lead-pretreated Swiss mice showed a significant induction. This enzymatic upregulation could provide a protective mechanism for oxidative stress in these mice.     

The effects of chronic alcohol and vitamin E consumption on aging pigments and learning performance in mice

Chronic ethanol consumption further accelerates age-related impairment of shuttle box avoidance learning in mice. The hypothesis was tested that the behavioral impairment is a result of brain lipofuscin pigment deposition, which may be accelerated by ethanol consumption and prevented by the antioxidant effects of pharmacological doses of vitamin E. Feeding an ethanol-containing liquid diet for 5 months did not increase the lipofuscin content when compared with mice pair-fed a liquid diet containing isocaloric amounts of sucrose or standard solid laboratory food containing nutritionally adequate amounts of vitamin E. Supplementation of diets with vitamin E decreased brain lipofuscin content in all groups but failed to prevent the age- or ethanol-induced learning deficit. There was no effect of chronic ethanol consumption on brain weights, DNA, RNA, or protein content.It is concluded that the age-related impairment of avoidance learning is accelerated by chronic alcohol consumption. At the molecular level this acceleration is not caused by an increased brain lipofuscin deposition nor is it prevented by the antioxidant effects of vitamin E.     

Infusions of acetaldehyde into the arcuate nucleus of the hypothalamus induce motor activity in rats

AimsThe hypothalamic arcuate nucleus (ARH) is one of the brain regions with the highest levels of catalase expression. Acetaldehyde, metabolized from ethanol in the CNS through the actions of catalase, has a role in the behavioral effects observed after ethanol administration. In previous studies acetaldehyde injected in the lateral ventricles or in the substantia nigra reticulata (SNR) mimicked the behavioral stimulant effects of centrally administered ethanol.Main methodsIn the present study we assessed the effects of acetaldehyde administered either into the ARH into a dorsal control or into the third ventricle on locomotion and rearing observed in 30 min sessions in an open field.Key findingsAcetaldehyde injected into the ARH induced horizontal locomotion and rearing for 20 min. In contrast, administration of acetaldehyde into a control site dorsal to the ARH did not have any effect on locomotion. Although acetaldehyde administration into the third ventricle also induced locomotion, the time course for the effect in this area was different from the time course following ARH injections. Acetaldehyde in the ARH produced a long lasting induction of locomotion, while with intraventricular injections the effects disappeared after 5 min.SignificanceThe present results are consistent with previous studies demonstrating that acetaldehyde is an active metabolite of ethanol, which can have locomotor stimulant properties when administered in the ventricular system of the brain or into specific brain nuclei. Some brain nuclei rich in catalase (i.e.; SNR and ARH) could be mediating some of the locomotor stimulant effects of ethanol through its conversion to acetaldehyde.     

Ethanol-induced hypothermia in mice: Influence of genotype on development of tolerance

Male mice of BALB/c, C57BL, DBA/2 strains and two lines of mice selectively bred for sensitivity to ethanol, Long-Sleep (LS) and Short-Sleep (SS), were tested for ethanol-induced hypothermia following varied doses of ethanol. The results show that the genotype as well as the dose of the drug determines the intensity and the duration of the effect. Repeated injection of ethanol results in the decrease of hypothermia in BALB/c mice and in C57BL, but not in DBA/2 mice, indicating that tolerance as measured in this study may not develop in certain genotypes of mice. The blood ethanol elimination data after repeated injections of ethanol indicate that the metabolic factors do not explain the changes observed in the hypothermic effects of repeated injections of ethanol.     

Analysis of candidate genes of spontaneous arthritis in mice deficient for interleukin-1 receptor antagonist

Previously, we identified a major quantitative trait locus (QTL) on mouse chromosome 1 that regulates the susceptibility to arthritis in an F2 population generated from arthritis-prone BALB/c and arthritis-resistant DBA/1 mice deficient for interleukin-1 receptor antagonist. To further select candidate genes for the QTL, we analyzed the expression patterns of arthritis in 38 F2 individuals and compared the expression levels of key candidate genes to the parental strains. Two distinct subpopulations of arthritic mice were identified in the 38 F2 mice. One subgroup of diseased mice was characterized by myeloid cell dominant inflammation, whereas the other was mainly associated with increased anti-apoptotic activities of inflammatory cells. Several differentially expressed important candidate genes in parental strains in the QTL region are relevant to myeloid cell, apoptotic activities, or to both. About one-quarter of those genes have been previously linked to arthritis in literature. The present study reveals two distinct subpopulations of arthritic mice with spontaneous arthritis due to deficiency for interleukin-1 receptor antagonist, suggesting that genes with function relevant to myeloid cell and/or apoptotic activities are most likely the key candidate genes for the QTL.     

Neurophysiological mechanisms in the genetics of ethanol sensitivity

Abstract

Cerebellar Purkinje neurons of long‐sleep (LS) mice express a higher sensitivity than do those of short‐sleep (SS) mice to the depressant effects of ethanol in situ, in vitro, and in intraocular cerebellar brain grafts. The ethanol sensitivity of Purkinje neurons is intrinsic to the cerebellum, may be associated with only certain brain areas, and shows a high genetic correlation with the behavioral sensitivity of mice to ethanol‐induced ataxia. Tolerance develops to the depressant effects of ethanol on cerebellar neurons in both lines of mice. However, ethanol‐tolerant LS mice are more sensitive to the electrophysiological effects of ethanol on Purkinje neurons than are ethanol‐tolerant SS mice. In addition, the behavioral sensitivity to this drug probably also involves noncerebellar neurons since neonatally cerebellectomized LS and SS mice retain a different sensitivity to the ataxic effects of ethanol.     

Alcohol withdrawal reactions and reserpine effects in inbred strains of mice

Mice of different inbred strains were treated with ethanol for 3 days, by inhalation of alcohol vapor and daily injections of pyrazole. Within strains, “alcohol-adapted” mice were compared with controls. The alcohol-adapted mice received 3.8% (w/v) alcohol in their drinking water for one week and 7.5% alcohol for the next 16 or 19 weeks. During the inhalation period, C57BL mice had lower blood alcohol levels than DBA mice, and alcohol-adapted mice had slightly lower blood levels than controls. On withdrawal the mice were examined repeatedly for convulsions elicited by handling, a measure of the intensity of withdrawal reactions. The withdrawal scores of C57BL mice were significantly lower than those of DBA, BALB or Swiss-Webster mice, more so than could be accounted for by the difference in blood alcohol levels. Mice of 3 strains were treated with reserpine and observed for behavioral effects, including convulsions on handling. Strain differences in reserpine effects closely paralleled the strain differences in alcohol withdrawal seizures.     

Rapid tolerance to ethanol and high voluntary alcohol consumption in mice selected for brain weight

Mice of two strains selected for small and large brain weight (SB and LB, respectively) had free access to 10% alcohol and water within three months. At the end of this period, they consumed alcohol in daily dose of 6.9 +/- 0.9 and 7.5 +/- 0.8 g/kg, respectively. After a period of imposed three-day abstinence, the alcohol consumption by the mice of these strains increased by 68.6 and 49.3%, respectively. Exploratory behavior of independent groups of mice from these strains was studied in the closed cross-maze. The animals were injected with ethanol (2.4 g/kg, i.p.) or vehicle twice with a weekly interval. In SB mice, the first ethanol administration increased the total time of maze exploration and the number of stereotyped visits. The second ethanol administration did not increase the time of exploration but increased the number of stereotyped visits even to the greater extent. The latter indicates the development of rapid tolerance and sensitization of these behaviors to the drug, respectively. The ethanol administration inhibited exploratory patrolling behavior and defecations. In LB mice, both the first and second ethanol administrations increased the number of stereotyped visits and decreased the exploration time and the number of defecations. The results do not support the psychomotor stimulant hypothesis of alcohol addiction. It is proposed that SB and LB mice may serve as models for Cloninger's types 1 and 2 alcoholics and may be useful for investigation of neuropharmacological mechanisms of stimulatory and inhibitory effects of ethanol.     

Genetic analysis of barrel field size in the first somatosensory area (SI) in inbred and recombinant inbred strains of mice

We measured the combined area of posterior medial barrel subfield (PMBSF) and anterior lateral barrel subfield (ALBSF) areas in four common inbred strains (C3H/HeJ, A /J, C57BL /6J, DBA/2J), B6D2F1, and ten recombinant inbred (RI) strains generated from C57BL/6J and DBA/2J progenitors (BXD) as an initial attempt to examine the genetic influences underlying natural variation in barrel field size in adult mice. These two subfields are associated with the representation of the whisker pad and sinus hairs on the contralateral face. Using cytochrome oxidase labeling to visualize the barrel field, we measured the size of the combined subfields in each mouse strain. We also measured body weight and brain weight in each strain. We report that DBA/2J mice have a larger combined PMBSF/ALBSF area (6.15 +/- 0.10 mm(2), n = 7) than C57BL /6J (5.48 +/- 0.13 mm(2), n = 10), C3H/HeJ (5.37 +/- 0.16 mm(2), n = 10), and A/J mice (5.04 +/- 0.09 mm(2), n = 15), despite the fact that DBA/2J mice have smaller average brain and body sizes. This finding may reflect dissociation between systems that control brain size with those that regulate barrel field area. In addition, BXD strains (average n = 4) and parental strains showed considerable and continuous variation in PMBSF/ALBSF area, suggesting that this trait is polygenic. Furthermore, brain, body, and cortex weights have heritable differences between inbred strains and among BXD strains. PMBSF/ALBSF pattern appears similar among inbred and BXD strains, suggesting that somatosensory patterning reflects a common plan of organization. This data is an important first step in the quantitative genetic analysis of the parcellation of neocortex into diverse cytoarchitectonic zones that vary widely within and between species, and in identifying the genetic factors underlying barrel field size using quantitative trait locus (QTL) analyses.     

Involvement of the serotonergic cerebral system in microwave-induced analgesia in mice of different genotypes

Under conditions of the formalin test, we studied changes in the level of analgesia induced by the action of low-intensity microwaves on the antinociceptive acupuncture point (AP) E36 in mice of strains CBA/CaLac (CBA) and C57BL/6j (C57) and in albino mongrel mice. Measurements were performed under control conditions and with experimentally induced decrease in the serotonin level in the brain (by injections of DL-parachlorophenylalanine, p-CPA). In the latter cases, the duration of the pain behavioral reaction increased despite irradiation of the AP E36. In mongrel, CBA, and C57 mice, the intensity of pain manifestations was 114.4, 29.0, and 21.1% greater, respectively, than in mice of these groups with no injections of p-CPA. These facts show that the serotonergic brain system is profoundly involved in the formation of analgesia after irradiation of the AP by low-intensity microwaves, and this involvement significantly depends on the genotype of the animals. Neirofiziologiya/Neurophysiology, Vol. 38, Nos. 5/6, pp. 495–497, September–December, 2006.     

Time course of ethanol's effects on brain prostaglandins in LS and SS mice

Prostaglandin synthesis inhibitors antagonize behavioral responses to alcohols. Recent work has shown that ethanol increases brain prostaglandin (PG) levels. The study reported here examined the time course for ethanol-stimulated brain PGE and PGF production in Long Sleep and Short Sleep mice, animals bred selectively for high vs. low acute response to ethanol. Increases in brain PGE levels correlated highly with the absorption phase but only partially with the elimination phase of ethanol. PGF levels correlated significantly with blood ethanol levels across the entire three hour period. These results, plus sex and genotype interactions, provide further evidence to support the hypothesis that ethanol produces its intoxicating effects to a significant degree through a prostaglandin mediated mechanism.     

Cyclo-glycyl-glutamine inhibits ethanol intake in P and Sprague-Dawley rats

Peptide inhibitors of ethanol consumption have shown promise. The purpose of this study was to test the cyclized form of the opioid-derived dipeptide, glycyl-L-glutamine to reduce ethanol consumption after either peripheral injections or site-specific injections into the nucleus accumbens (NAC) of high drinking and low drinking rats. Following I.P. cyclo-glycyl-glutamine (c-GQ), the data show a mean decrease in ethanol intake of 34.4% in P rats, and 39.4% in Sprague-Dawley rats at doses between 5 and 25mg/kg. The data show that peripherally administered c-GQ is effective in reducing ethanol consumption in both high (P) and low (SD) drinking strains of rats and suggests a therapeutic potential.     

JNK Pathway Activation Is Controlled by Tao/TAOK3 to Modulate Ethanol Sensitivity

Neuronal signal transduction by the JNK MAP kinase pathway is altered by a broad array of stimuli including exposure to the widely abused drug ethanol, but the behavioral relevance and the regulation of JNK signaling is unclear. Here we demonstrate that JNK signaling functions downstream of the Sterile20 kinase family gene tao/Taok3 to regulate the behavioral effects of acute ethanol exposure in both the fruit fly Drosophila and mice. In flies tao is required in neurons to promote sensitivity to the locomotor stimulant effects of acute ethanol exposure and to establish specific brain structures. Reduced expression of key JNK pathway genes substantially rescued the structural and behavioral phenotypes of tao mutants. Decreasing and increasing JNK pathway activity resulted in increased and decreased sensitivity to the locomotor stimulant properties of acute ethanol exposure, respectively. Further, JNK expression in a limited pattern of neurons that included brain regions implicated in ethanol responses was sufficient to restore normal behavior. Mice heterozygous for a disrupted allele of the homologous Taok3 gene (Taok3Gt) were resistant to the acute sedative effects of ethanol. JNK activity was constitutively increased in brains of Taok3Gt/+ mice, and acute induction of phospho-JNK in brain tissue by ethanol was occluded in Taok3Gt/+ mice. Finally, acute administration of a JNK inhibitor conferred resistance to the sedative effects of ethanol in wild-type but not Taok3Gt/+ mice. Taken together, these data support a role of a TAO/TAOK3-JNK neuronal signaling pathway in regulating sensitivity to acute ethanol exposure in flies and in mice.     

Neutron irradiation of late mouse embryos (15-19 days) in utero

Pregnant female C57B1/6 mice were irradiated with a single whole-body dose of 0.5 Gy neutrons. The F1 hybrid embryos were exposed to the neutrons in utero on Day 17 +/- 2 of gestation. 178/439 (40.6%) of the irradiated fetuses and 26/217 (12%) of the control mice died within 2 weeks after birth. In both irradiated and control mice, most deaths (95 and 77%, respectively) occurred within 3 days of birth: most animals in both groups died on Day 2. There was no significant difference in the number of living young born per litter (7.2) between the neutron-irradiated mothers and their unirradiated controls. The irradiated mice weighed significantly less than their controls. On the first day after birth, body weights of mice irradiated in utero averaged only 85% of control weights. Body weights did not reach control levels until 6 months after birth. Several organs were weighed at regular intervals in both irradiated and control mice. Spleens and thymus glands showed no significant differences between the two groups. The livers and kidneys of the irradiated mice weighed slightly less than their controls. The brain weight of 21-day-old neutron-irradiated mice was 30-35% less than control brains. The weight loss of the brain was not only a relative loss, but also an absolute one, based on brain weight/body weight ratios. Histological analysis of the central nervous system showed pycnotic nuclei, inhibition of mitosis in neuroblasts, and cell death in the irradiated brains. The weight reduction of the brain was not due to water loss. Our hypothesis is that the early mortality after birth is related to the killing of the radiation-sensitive neuroblasts. When newborn mice (1-7 days old) were irradiated in vivo with the same neutron dose of 0.5 Gy, neither the reduction in brain weight nor the early mortality was observed. The early deaths of the neutron-irradiated mouse embryos does not appear to be caused by either the hematological or the gastrointestinal radiation syndrome.     

Actions and interactions of growth hormone and insulin-like growth factor-II: body and organ growth of transgenic mice

To characterize long-term actions and interactions of growth hormone (GH) and insulin-like growth factor-II (IGF-II) on postnatal body and organ growth, hemizygous phosphoenolpyruvate carboxykinase (PEPCK)-human IGF-II transgenic mice were crossed with hemizygous PEPCK-bovine GH transgenic mice. The latter are characterized by two-fold increased serum levels of IGF-I and exhibit markedly increased body, skeletal and organ growth. Four different genetic groups were obtained: mice harbouring the IGF-II transgene (I), the bGH transgene (B), or both transgenes (IB), and non- transgenic controls (C). These groups of mice have previously been studied for circulating IGF-I levels (Wolf et al., 1995a), whereas the present study deals with body and organ growth. Growth curves (week 3 to 12) were estimated by regression with linear and quadratic components of age on body weight and exhibited significantly (p < 0.001) greater linear coefficients in B and IB than in I and C mice. The linear coefficients of male I and C mice were significantly (p < 0.001) greater than those of their female counterparts, whereas this sex-related difference was absent in the bGH transgenic groups. The weights of internal organs as well as the weights of abdominal fat, skin and carcass were recorded from 3.5- to 8- month-old mice. In addition, organ weight-to-body weight-ratios (relative organ weights) were calculated. Except for the weight of abdominal fat, absolute organ weights were as a rule significantly greater in B and IB than in I and C mice. IGF-II overproduction as a tendency increased the weights of kidneys, adrenal glands, pancreas and uterus both in the absence and presence of the bGH transgene. Analysis of relative organ weights demonstrated significant (p < 0.05) effects of elevated IGF- II on the relative growth of kidneys (males and females) and adrenal glands (females), confirming our previous report on organ growth of PEPCK-IGF-II transgenic mice. In females, IGF-II and GH overproduction were additive in stimulating the growth of spleen and uterus, providing evidence for tissue-specific postnatal growth promoting effects by IGF-II in the presence of elevated IGF-I     

A biochemical and toxicological study with diethyl 2-phenyl-2-tellurophenyl vinylphosphonate in a sub-chronic intraperitoneal treatment in mice

Diethyl-2-phenyl-2-tellurophenyl vinylphosphonate (DPTVP) is an organotellurium compound with low toxicity after subcutaneous administration in mice. This study evaluated possible in vivo and ex vivo toxicological effects of daily injections of DPTVP for 12 days in mice, using the intraperitoneal administration. This route potentially increases the pharmacokinetics of absorption, distribution, metabolism and toxicity of DPTVP. Treatment with DPTVP (0, 30, 50, 75, 100, 250, 350 or 500 micromol/kg) were not associated with mortality or body weight loss. Nevertheless, the liver and liver-to-body weight ratio increased in groups treated with 350 and 500 micromol/kg of DPTVP. However, plasmatic aspartate and alanine aminotransferase activities (classical markers of hepatotoxicity) were not increased after diethyl-2-phenyl-2-tellurophenyl vinylphosphonate administration. Hepatic, renal and cerebral thiobarbituric acid reactive substances (TBARS), delta-ALA-D activity and Vitamin C levels were not modified after DPTVP treatment. Renal and hepatic superoxide dismutase (SOD) and catalase (CAT) were unchanged after DPTVP treatment. Conversely, SOD activity significantly increased in brain in groups treated with 50, 75, 100 and 500 micromol/kg of DPTVP treated groups. Our findings corroborates that brain is a potential target for organochalcogen action. The absence of severe overt signs of toxicity after sub-chronic exposure to DPTVP reinforces the necessity for more detailed pharmacological studies concerning this new organotellurium compound.     

Increased ethanol intake and preference in cyclin D2 knockout mice

Inhibitory effects of passive ethanol exposure on brain neurogenesis have been extensively documented in animal models. In contrast, a role of brain neurogenesis in ethanol self-administration has not been addressed, as yet. The aim of this study was to assess intake of, and preference for, ethanol solutions [2-16% (v/v)] in a mouse model of adult neurogenesis deficiency based on permanent knockout (KO) of cyclin D2 (Ccnd2). Wild type (WT) and Ccnd2 KO mice did not differ in 2% and 4% ethanol intake. The KO group consumed significantly more ethanol in g/kg when offered with 8% or 16% ethanol as compared with the WT controls. The WT and KO mice did not differ in 2% ethanol preference, but the KO group showed a significantly higher preference for 4-16% ethanol. Animal and human studies have suggested that the low level of response to the sedative/hypnotic effects of alcohol is genetically associated with enhanced alcohol consumption. However, in this study, there were no between-genotype differences in ethanol-induced loss of righting reflex. Previous reports have also suggested that high ethanol intake is genetically associated with the avidity for sweets and better acceptance of bitter solutions. However, the KO and WT mice consumed similar amounts of saccharin solutions and the KOs consumed less quinine (i.e. bitter) solutions as compared with the WTs. In conclusion, these results may indicate that Ccnd2 and, possibly, brain neurogenesis are involved in central regulation of ethanol intake in mice.     

Multiple-trait QTL mapping for body and organ weights in a cross between NMRI8 and DBA/2 mice

Multiple-trait analyses have been shown to improve the detection of quantitative trait loci (QTLs) with multiple effects. Here we applied a multiple-trait approach on obesity- and growth-related traits that were surveyed in 275 F2 mice generated from an intercross between the high body weight selected line NMRI8 and DBA/2 as lean control. The parental lines differed 2.5-fold in body weight at the age of 6 weeks. Within the F2 population, the correlations between body weight and weights of abdominal fat weight, muscle, liver and kidney at the age of 6 weeks were about 0.8. A least squares multiple-trait QTL analysis was performed on these data to understand more precisely the cause of the genetic correlation between body weight, body composition traits and weights of inner organs. Regions on Chr 1, 2, 7 and 14 for body weights at different early ages and regions on Chr 1, 2, 4, 7, 14, 17 and 19 for organ weights at 6 weeks were found to have significant multiple effects at the genome-wide level.