Potentiation of responses to AMPA on central neurones by LY392098 and LY404187 in vivo

Enhancement of AMPA receptor mediated synaptic excitation has the potential to aid in the treatment of several psychiatric conditions. To test such claims there is a need to develop more potent compounds than those presently available and to demonstrate that they cross the blood-brain barrier to affect responses at central AMPA receptors. We have now completed in vivo tests with two such compounds, the newly discovered biarylpropylsulfonamides, LY392098 and LY404187, on spinal and hippocampal neurones in anaesthetised rats. In the initial study on spinal neurones, LY392098 (30-1000 microg/kg i.v.) dose-dependently increased responses to iontophoretically administered AMPA but not those to NMDA. Subsequently in a more detailed follow-up study on hippocampal neurones, LY392098 (1-100 microg/kg i.v.) and LY404187 (1-100 microg/kg i.v.) enhanced in a dose-dependent manner responses to AMPA. Responses to NMDA were also enhanced but to a less extent. Such enhanced responses to NMDA, but not those to AMPA, were reduced by the NMDA antagonist, ketamine (0.5-1 mg/kg i.v.) whereas the selective AMPA antagonist, LY300168 (GYKI53655; 1 mg/kg i.v.), reduced responses to both NMDA and AMPA. LY392098 also potentiated the synaptic excitation of dentate granule cells following perforant path stimulation. These combined data show that, at doses not dissimilar to those affecting behavioural responses (1-1000 microg/kg; see accompanying papers), the two new drugs cross the blood-brain barrier to affect directly the sensitivity of central AMPA receptors and enhance synaptic excitation in vivo.

Highly efficient gene transfer into cord blood nonobese diabetic/severe combined immunodeficiency repopulating cells by oncoretroviral vector particles pseudotyped with the feline endogenous retrovirus (RD114) envelope protein

Limited expression of the amphotropic envelope receptor is a recognized barrier to efficient oncoretroviral vector-mediated gene transfer. Human hematopoietic cell lines and cord blood-derived CD34(+) and CD34(+), CD38(-) cell populations and the progenitors contained therein were transduced far more efficiently with oncoretroviral particles pseudotyped with the envelope protein of feline endogenous virus (RD114) than with conventional amphotropic vector particles. Similarly, human repopulating cells from umbilical cord blood capable of establishing hematopoiesis in immunodeficient mice were efficiently transduced with RD114-pseudotyped particles, whereas amphotropic particles were ineffective at introducing the proviral genome. After only a single exposure of CD34(+) cord blood cells to RD114-pseudotyped particles, all engrafted nonobese diabetic/severe combined immunodeficiency mice (15 of 15) contained genetically modified human bone marrow cells. Human cells that were positive for enhanced green fluorescent protein represented as much as 90% of the graft. The use of RD114-pseudotyped vectors may be advantageous for therapeutic gene transfer into hematopoietic stem cells. (Blood. 2000;96:1206-1214)

Moxonidine, a selective imidazoline-1 receptor agonist, suppresses the effects of ethanol withdrawal on the acoustic startle response in rats

BACKGROUND

There is a need for improved treatments for ethanol withdrawal in humans. Previously, ethanol withdrawal has been shown to enhance the acoustic startle response in rats. Because many ethanol withdrawal symptoms are caused by autonomic hyperactivity, we examined the effects of two antihypertensives, the imidazoline(I)(1) agonist moxonidine and the alpha(2)-adrenergic partial agonist clonidine, on the ethanol-withdrawal-enhanced acoustic startle response in rats. d-amphetamine-enhanced startle served as a positive control.

METHODS

Male, Long-Evans rats were made ethanol-dependent through unlimited access to liquid diet containing 6.7% v/v ethanol for 10 days. The concentration of ethanol was reduced to 3.3% v/v on the 11th day. On the 12th day, the rats received control diet. The acoustic startle response was tested 24 hours following the withdrawal of ethanol. Control rats were maintained on control liquid diet throughout the experiment.

RESULTS

As has been shown previously, withdrawal from the chronic ingestion of ethanol significantly enhanced the acoustic startle response. Pretreatment with moxonidine (0.01, 0.1, and 1.0 mg/kg, subcutaneously), but not clonidine (0.3, 1.0, and 3.0 mg/kg, subcutaneously), significantly attenuated the ethanol withdrawal-induced elevation of the acoustic startle response. Moxonidine did not suppress the elevation in the startle response caused by d-amphetamine.

CONCLUSIONS

These results indicate that I(1) receptors can play an important role in ethanol withdrawal and that moxonidine may be useful for the treatment of ethanol withdrawal in humans.

Efficient gene transfer into human cord blood CD34+ cells and the CD34+CD38- subset using highly purified recombinant adeno-associated viral vector preparations that are free of helper virus and wild-type AAV

Recombinant adeno-associated viral (rAAV) vectors have been evaluated for their ability to transduce primitive hematopoietic cells. Early studies documented rAAV-mediated gene expression during progenitor derived colony formation in vitro, but studies examining genome integration and long-term gene expression in hematopoietic cells have yielded conflicting results. Such studies were performed with crude vector preparations. Using improved methodology, we have generated high titer, biologically active preparations of rAAV free of wild-type AAV (less than 1/107particles) and adenovirus. Transduction of CD34+ cells from umbilical cord blood was evaluated with a bicistronic rAAV vector encoding the green fluorescent protein (GFP) and a trimetrexate resistant variant of dihydrofolate reductase (DHFR). Freshly isolated, quiescent CD34+ cells were resistant to transduction (less than 4%), but transduction increased to 23 +/- 2% after 2 days of cytokine stimulation and was further augmented by addition of tumor necrosis factor alpha (51 +/- 4%) at a multiplicity of infection of 106. rAAV-mediated gene expression was transient in that progenitor derived colony formation was inhibited by trimetrexate. Primitive CD34+ and CD34+, CD38- subsets were sequentially transduced with a rAAV vector encoding the murine ecotropic receptor followed by transduction with an ecotropic retroviral vector encoding GFP and DHFR. Under optimal conditions 41 +/- 7% of CD34+ progenitors and 21 +/- 6% of CD34+, CD38- progenitors became trimetrexate resistant. These results document that highly purified rAAV transduce primitive human hematopoietic cells efficiently but gene expression appears to be transient. Gene Therapy (2000) 7, 183-195.

The selective mGlu2/3 receptor agonist LY354740 attenuates morphine-withdrawal-induced activation of locus coeruleus neurons and behavioral signs of morphine withdrawal

Naltrexone-precipitated morphine withdrawal induces hyperactivity of locus coeruleus (LC) neurons, as well as a plethora of behavioral withdrawal signs. Previous research has demonstrated that an increased release of glutamate and activation of AMPA receptors, particularly in the LC, play an important role in opiate withdrawal. LY354740 is a novel Group II metabotropic glutamate mGlu2/3 receptor agonist that decreases the release of glutamate. Therefore, we investigated the effect of LY354740 on naltrexone-precipitated morphine-withdrawal-induced activation of LC neurons and behavioral signs of morphine withdrawal. In in vivo recordings from anesthetized rats, pretreatment with LY354740 (3-30 mg/kg, s.c.) dose-dependently attenuated the morphine-withdrawal-induced activation of LC neurons. In unanesthetized, morphine-dependent animals, pretreatment with LY354740 (3-30 mg/kg, s.c.) dose-dependently suppressed the severity and occurrence of many naltrexone-precipitated morphine-withdrawal signs. These results indicate mGlu2/3 receptor agonists: (1) can attenuate the morphine-withdrawal-induced activation of LC neurons and many behavioral signs of morphine withdrawal; and (2) may have therapeutic effects in man for the treatment of opiate withdrawal.