Alberto Oliverio

Genotype-dependent sensitivity and tolerance to morphine and heroin. Dissociation between opiate-induced running and analgesia in the mouse.

Morphine and heroin-induced running activity (running fit), analgesia and tolerance were studied in the inbred strains of mice BALB/cJ, C57BL/6J and DBA/2J. Acute tolerance developed in all strains tested within 48 h. The effects of the opiates on the running fit and analgesia were strain-dependent and a negative strain correlation was evident between the two measures. The development and the recovery from acute tolerance were also genetically determined. It is concluded that the motor and analgesic effects of morphine in the mouse are two distinct phenomena and that the same neuronal and biochemical model cannot explain them. The results are discussed in relation to the brain regional and biochemical differences reported for these strains.

Exploratory activity: Genetic analysis of its modification by scopolamine and amphetamine.

Abstract Short-term exploratory activity was found to be significantly higher in C57BL/6By than in BALB/cBy inbred mice. Scopolamine reversed the activity levels in these strains. Basal exploratory activity levels and the effects of scopolamine on this behavioral measure assessed in these two strains, their reciprocal F 1 hybrids, their recombinant inbred strains and three C57BL/6 congenic lines permitted characterization of a gene exerting a major effect on short-term exploratory activity [ Exa , linked to H(w26), chromosome 4 (LG VIII)] and of a gene modulating the effects of scopolamine in this behavior, [ Sco , linked to H -2, chromosome 17 (LG IX)]. Amphetamine exerted opposite effects in relation to those exerted by scopolamine on activity and its action was found to be determined by a polygenic system.

In vivo gene therapy of metachromatic leukodystrophy by lentiviral vectors: correction of neuropathology and protection against learning impairments in affected mice

Metachromatic leukodystrophy (MLD) is a lipidosis caused by deficiency of arylsulfatase A (ARSA). Although the genetics of MLD are known, its pathophysiology is not understood. The disease leads to progressive demyelination and early death and no effective treatment is available. We used lentiviral vectors to deliver a functional ARSA gene (human ARSA) into the brain of adult mice with germ-line inactivation of the mouse gene encoding ARSA, As2. We report sustained expression of active enzyme throughout a large portion of the brain, with long-term protection from development of neuropathology and hippocampal-related learning impairments. We show that selective degeneration of hippocampal neurons is a central step in disease pathogenesis, and provide evidence that in vivo transfer of ARSA by lentiviral vectors reverts the disease phenotype in all investigated areas. Therefore, in vivo gene therapy offers a unique option for MLD and other storage diseases affecting the central nervous system.

Stress induces region specific alterations in microRNAs expression in mice.

Several studies have demonstrated that exposure to both acute and chronic aversive stimuli can affect neural activity in different brain areas. In particular it has been shown that stressful events can induce not only short-term changes in neural transmission and gene regulation, but also long-term changes that can lead to structural modification. In this study we investigated, in CD1 mice, the effects of single or repeated exposures to restraint stress (2h for 1 or 5 consecutive days) in the frontal cortex on a crucial class of gene expression regulators, the microRNAs (miRs).First we performed a microarray profiling on RNA extracted from the frontal cortex of mice exposed to acute or repeated restraint stress. The results indicated a prominent increase in the expression levels of different miRs after acute stress while only minor changes were observed after repeated restraint. The Northern blot analysis on selected miRs confirmed an increase after acute restraint for let-7a, miR-9 and miR 26-a/b. Finally, Northern blot analysis of the selected miRs on RNA extracted from the hippocampus of stressed mice demonstrated that such changes were region specific, as no differences were observed in the hippocampus. These data suggest that control of mRNA translation through miRs is an additional mechanism by which stressful events regulates protein expression in the frontal cortex.

Effects of immobilization stress on dopamine and its metabolites in different brain areas of the mouse: role of genotype and stress duration

Immobilization stress induced, in mice of both C57BL/6 (C57) and DBA/2 (DBA) strains, an increase in dihydroxyphenylacetic acid (DOPAC)/dopamine (DA) and homovanillic acid (HVA)/DA ratios and a reduction of 3-methoxytyramine (3-MT)/DA ratio in the caudatus putamen (CP) and nucleus accumbens septi (NAS). These effects were already evident after 30 min stress in the NAS, while in the CP 120 min were needed in order to show the effects of stress. Immobilization did not produce any effects on dopaminergic metabolism in the frontal cortex (FC) of the C57 strain either after 30 or after 120 min stress while in mice of the DBA strain a time-dependent effect of stress on the HVA/DA ratio was evident. When B6D2F1 hybrids were considered, the effects produced by 120 min immobilization in the CP and the NAS paralleled those observed in parental strains, while in the FC 120 min stress induced the same increase of HVA observed in DBA mice, thus suggesting that the pattern of response in the FC that characterizes the DBA strain may be inherited through a dominant pattern of inheritance.

Chronic stress enhances apomorphine-induced stereotyped behavior in mice: Involvement of endogenous opioids

Mice subjected to repeated stressful experiences showed an increase in stereotypic climbing behavior induced by apomorphine thus suggesting a modified sensitivity of dopaminergic receptors. Naltrexone, injected before each stressful experience, reversed this effect of chronic stress indicating an involvement of endogenous opioids.

N-methyl-D-aspartate and dopamine receptor involvement in the modulation of locomotor activity and memory processes

Abstract In this study we report on the effects of N-methyl-d-aspartate (NMDA)- and dopamine (DA)-receptor manipulation on the modulation of one-trial inhibitory avoidance response and the encoding of spatial information, as assessed with a non-associative task. Further, a comparison with the well-known effects of the manipulation of these two receptor systems on locomotor activity is outlined. It is well assessed that NMDA-receptor blockage induces a stimulatory action on locomotor activity similar to that exerted by DA agonists. There is evidence showing that the nucleus accumbens is involved in the response induced by both NMDA antagonists and DA agonists. We show results indicating a functional interaction between these two neural systems in modulating locomotor activity, with D2 DA-receptor antagonists (sulpiride and haloperidol) being more effective than the D1 antagonist (SCH 23390) in blocking MK-801-induced locomotion. A different profile is shown in the effects of NMDA antagonists and DA agonists in the modulation of memory processes. In one-trial inhibitory avoidance response, NMDA antagonists (MK-801 and CPP) impair the response on test day, while DA agonists exert a facilitatory effect; furthermore, sub-effective doses of both D1 (SKF 23390) and D2 (quinpirole) are able to attenuate the impairing effect in a way similar to that induced by NMDA antagonists. The effects of NMDA- and DA-acting drugs on the response to spatial novelty, as assessed with a task designed to study the ability of animals to react to discrete spatial changes, are in good accord with the effects observed on passive avoidance. The results show that NMDA as well as DA antagonists, at low doses, selectively impair the reactivity of mice to spatial changes. In a last series of experiments, the possible role of NMDA receptors located in the nucleus accumbens was investigated regarding reactivity to spatial novelty. The experiments gave apparently contrasting results: while showing an impairing effect of focal administrations of NMDA antagonists in the nucleus accumbens on reactivity to spatial novelty, no effect of ibotenic acid lesions of the same structure was observed.

Repeated administration of phencyclidine, amphetamine and MK-801 selectively impairs spatial learning in mice: a possible model of psychotomimetic drug-induced cognitive deficits

Cognitive deficits are a key feature of schizophrenia. N-Methyl-D-aspartate (NMDA) receptor antagonists and amphetamine are known to induce psychotic behaviors and cognitive deficits in animals and humans, often affecting visuo-spatial abilities. Phencyclidine (PCP), MK-801 and amphetamine (AMPH) have been used in pharmacological animal models of schizophrenia, but none of these models has focused so far on spatial learning after repeated administration of the drugs. The objective of this study was to test whether repeated administration of PCP, AMPH or MK-801 influenced the performance of mice in a non-associative spatial learning test. CD-1 male mice were given i.p. daily injections of either saline, PCP (5.0, 10.0 mg/kg), AMPH (2.5, 5 mg/kg) or MK-801 (0.3, 0.6 mg/kg), for 5 days. On day 6 all mice were tested in an open field containing five different objects. After three sessions of habituation, each animals reactivity to object displacement and object substitution was assessed. No significant differences among treatment groups were observed in object exploration or locomotion during the habituation phase. Five days of repeated PCP, AMPH or MK-801 administration selectively and differentially impaired the ability of mice to discriminate a spatial change, while leaving intact the ability to react to a non-spatial change. These data suggest that neurobiological adaptations to drug regimens known to induce psychotic behaviors and alterations in locomotor activity or stereotypies can also alter spatial learning, as assessed in this test, thus indicating that these regimens could also mimic some of the cognitive deficits observed in schizophrenia.

A genetic analysis of morphine-induced running and analgesia in the mouse.

A genetic analysis of morphine-induced analgesia and activity was conducted in mice belonging to the strains BALB/cJ, C57BL/6J, DBA/2J and to their F1 and backcross progenies. The results support previous findings showing that a negative correlation is evident between these two behavioral measures and support that their mode of inheritance is characterized by dominance or partial dominance. The biometric analysis conducted on the parental, F1 hybrid and backcross populations indicates very clearly that the effects of morphine are genetically determined.

A long-lasting cholinesterase inhibitor affecting neural and behavioral processes.

A series of analogues of physostigmine were prepared with the aim of investigating their inhibitory effects on acetylcholinesterase in the treatment of Alzheimers disease. One of the isomers prepared was evaluated for its anticholinesterase activity in vivo, acute toxicity, and some behavioral effects. This compound was a competitive inhibitor of the enzyme and was found to antagonize the stimulating effect produced by scopolamine on locomotor activity and to facilitate memory consolidation.