The α5-GABAAR inverse agonist MRK-016 upregulates hippocampal BDNF expression and prevents cognitive deficits in LPS-treated mice, despite elevations in hippocampal Aß.

Alzheimer's disease is marked by the presence of amyloid-beta (Aß) plaques, elevated central cytokine levels, dysregulation of BDNF-related gene expression, and cognitive decline. Previously, our laboratory has demonstrated that repeated administration of peripheral LPS is sufficient to significantly increase the presence of central Aß in the hippocampus, and that this upregulation corresponds with deficits in learning and memory. We have also previously demonstrated that the inverse benzodiazepine agonist MRK-016 (MRK) can protect against memory acquisition and consolidation errors in mice. To extend these findings, the current study explored the protective effects of MRK in the context of LPS-induced hippocampal Aß accumulation. Hippocampal Aß was significantly elevated, relative to saline-treated animals, following seven days of peripheral LPS injections. Animals were then trained in a contextual fear conditioning paradigm and were immediately treated with MRK or saline once training was complete. Behavioral testing occurred the day after training. Results from this study demonstrate that repeated injections of LPS significantly elevate hippocampal Aß, and inhibit acquisition of contextual fear. Post-training treatment with MRK restored behavioral expression of fear in LPS-treated animals, despite elevated hippocampal Aß, an effect that may be attributed to increased BDNF mRNA expression. Therefore, our data indicate that MRK can prevent LPS- induced cognitive deficits associated with elevated Aß, and restore hippocampal BDNF expression.

Pre-treatment of C57BL6/J mice with the TLR4 agonist monophosphoryl lipid A prevents LPS-induced sickness behaviors and elevations in dorsal hippocampus interleukin-1ß, independent of interleukin-4 expression.

Peripheral administration of lipopolysaccharide (LPS) elevates production of pro-inflammatory cytokines, and motivates the expression of sickness behaviors. In this study, we tested the ability of an LPS-derived adjuvant, monophosphoryl lipid A (MPLA), to prevent LPS-induced sickness behaviors in a burrowing paradigm. Testing occurred over a three-day period. Animals received a single injection of either MPLA or saline the first two days of testing. On day three, animals received either LPS or saline. Tissue from the dorsal hippocampus was collected for qRT-PCR to assess expression of IL-1ß and IL-4. Results indicate that, during the pre-treatment phase, administration of MPLA induces an immune response sufficient to trigger sickness behaviors. However, we observed that animals pre-treated with MPLA for two days were resistant to LPS-induced sickness behaviors on day three. Results from the qRT-PCR analysis indicated that LPS-treated animals pre-treated with MPLA expressed significantly less IL-1ß compared to LPS-treated animals pre-treated with saline. However, we did not observe a significant difference in IL-4 expression between groups. Therefore, results indicate that under the given parameters of the study, MPLA pre-treatment protects against LPS-induced sickness behaviors, at least in part, by decreasing expression of the pro-inflammatory cytokine IL-1ß.

Administration of the inverse benzodiazepine agonist MRK-016 rescues acquisition and memory consolidation following peripheral administration of bacterial endotoxin.

Recent evidence suggests that inflammation-induced decrements in cognitive function can be mitigated via manipulation of excitatory or inhibitory transmission. We tested the ability of the inverse benzodiazepine agonist, MRK-016 (MRK) to protect against LPS-induced deficits in memory acquisition and consolidation, using a contextual fear conditioning (CFC) paradigm. In Experiment One, mice received lipopolysaccharide (LPS) and/or MRK injections prior to CFC training, and were then tested 24h after training. In Experiment Two, animals received similar treatment injections immediately after training, and were tested 24h later. Additionally, hippocampal samples were collected 4h after LPS injections and immediately after testing, to evaluate brain-derived neurotrophic factor (BDNF) and insulin-like growth factor 1 (IGF-1) mRNA expression. Results indicate that MRK can protect against LPS-induced learning/memory decrements in both paradigms. We also found, in both paradigms, that animals treated with LPS/Saline expressed significantly less BDNF mRNA when compared to Saline/Saline-treated animals 4h after LPS administration, but that MRK did not restore BDNF expression levels. Further, treatment administrations had no effect on IGF-1 mRNA expression at any collection time-point. In summary, MRK-016 can protect against LPS-induced deficits in memory acquisition and consolidation, in this hippocampus-dependent paradigm, though this protection occurs independently of recovery of BDNF expression.

Effects of diethylstilboestrol on testicular function and luteinizing hormone receptors.

Adult male Fisher-344 rats were implanted with DES-filled or empty Silastic capsules. After 14 weeks, capsules were removed and a second group of rats received DES capsules. Seven weeks later, all the rats were sacrificed. DES treatment decreased body, testes and seminal vesicle weights, and removal of the capsules partially restored the weight of these organs. The concentration of testicular LH receptors was increased by DES treatment. Circulating PRL levels were increased and gonadotropin levels were reduced in all animals having received DES at anytime. Plasma testosterone (T) levels were similar in all groups, but testicular T levels were reversibly decreased by DES. Similarly, whereas basal incubation media T levels were unchanged by DES treatment, the steroidogenic response in vitro to hCG was abolished by the presence of DES, and removal of the capsules restored this response. It appears that in this animal model DES and PRL exert opposing effects on testicular LH receptor.

Programs for radioimmunoassays and radioreceptorassays using SPSS-X.

Two sets of programs written using SPSS-X, and designed for the analysis of data obtained by radioimmunoassay or radioreceptorassay are presented. The main advantages of the programs are that they are easily edited, their commands are simple and logical, and they can be used for any type of radioimmunoassay or radioreceptorassay, respectively. The programs for radioimmunoassay can also be used for fluorescenceimmunoassay and luminescenceimmunoassay.

Infertility in transgenic female mice with human growth hormone expression: evidence for luteal failure.

Introduction of the human growth hormone (hGH) gene fused with mouse metallothionein I promoter into domestic mice leads to ectopic synthesis of hGH, marked stimulation of somatic growth, and female sterility. Transgenic females (produced by mating transgenic males to normal females) mated but failed to become pregnant or pseudopregnant as evidenced by the recurrence of vaginal plugs every 5-7 days. Daily injections of 1 mg progesterone, starting on day 1 postcoitum (p.c.), maintained pregnancy, suggesting that the sterility of these animals is due to inadequate luteal function. In ovariectomized female transgenic mice, median eminence (ME) turnover of dopamine (DA) was increased, and plasma prolactin (PRL) levels were reduced, presumably because of the known lactogenic activity of hGH in rodents. From these observations we suspected that either 1) the corpora lutea of these animals are unresponsive to lactogenic hormones, or 2) hGH by stimulating tuberoinfundibular dopaminergic (TIDA) neurons interferes with the increase in PRL release that normally follows mating and this, in turn, leads to luteal failure. To distinguish between these possibilities, transgenic females were treated with PRL-secreting ectopic pituitary transplants from normal females of the same strain on day 1 p.c. Eight of ten treated females became pregnant and delivered litters. We conclude that infertility of transgenic female mice with hGH expression is due to activation of the TIDA system, suppression of endogenous PRL release, and luteal deficiency.

Experimental ocular herpetic infections in rabbits. Treatment with 9-([2-hydroxy-1-(hydroxymethyl)ethoxy]methyl)guanine.

A new acyclic nucleoside, 9-([2-hydroxy-1-(hydroxymethyl)ethoxy]methyl)guanine (BIOLF-62), was found to be efficacious in the treatment of experimental ocular herpes simplex virus infections in rabbits. Complete healing of herpetic lesions occurred in a majority of animals after six days of topical treatment, three times per day. No toxic effects were observed in uninfected, drug-treated eyes. The BIOLF-62 treatment blocked viral replication in infected eyes sufficiently to make recovery of virus from any of the drug-treated eyes impossible, whereas virus was recovered from all placebo-treated eyes.

Sensitivity of equine herpesviruses 1 and 3 in vitro to a new nucleoside analogue, 9-[[2-hydroxy-1-(hydroxymethyl) ethoxy] methyl] guanine.

The following members of the Herpetoviridae family were tested to determine their sensitivities to the new antiviral drug, BIOLF-62: equine herpesvirus types 1 and 3, human herpesvirus types 1 and 2, swine herpesvirus, bovine herpesvirus type 4, feline herpesvirus, canine herpesvirus, and herpes simiae virus. Equine herpesviruses 1 and 3, human herpesviruses 1 and 2, and herpes simiae virus were all sensitive to BIOLF-62 at concentrations of less than 0.55 micrograms/ml. Equine herpesvirus types 1 and 3 were particularly sensitive, viral median effective dose (ED50) concentrations of the drug being only 0.033 and 0.16 micrograms/ml, respectively. Such high antiviral potency and low cell toxicity indicate that BIOLF-62 might be useful in the treatment of infected animals.