Serotonin1A receptor deletion does not interact with maternal separation-induced increases in startle reactivity and prepulse inhibition deficits

Rationale  

Early life stress is a risk factor for the development of psychopathology in later life. Consequences of adverse life events, however, may depend on the genetic makeup of an individual. Reduced serotonin_1A receptor function may predispose to the development of anxiety disorders.     

GABA(A)-benzodiazepine receptor complex sensitivity in 5-HT(1A) receptor knockout mice on a 129/Sv background

Previous studies in 5-HT(1A) receptor knockout (1AKO) mice on a mixed Swiss Websterx129/Sv (SWx129/Sv) and a pure 129/Sv genetic background suggest a differential gamma-aminobutyric acid (GABA(A))-benzodiazepine receptor complex sensitivity in both strains, independent from the anxious phenotype. To further investigate these discrepancies, various GABA(A)-benzodiazepine receptor ligands were tested in different behavioral paradigms in 1AKO and wild type (WT) mice on a 129/Sv background. 1AKO and WT mice responded comparably to alprazolam, flumazenil, alcohol and pentylenetetrazol as measured in the stress-induced hyperthermia paradigm. In addition, sedative-anesthetic effects of pentobarbital measured via the righting reflex were similar and a selected dose of diazepam exerted similar anxiolytic effects in both genotypes in the elevated plus maze. In conclusion, 1AKO mice on a 129/Sv background have undisturbed GABA(A)-benzodiazepine receptor sensitivity in contrast to those described on a mixed Swiss Websterx129/Sv background. The anxious phenotype of 1AKO mice seems to occur independent of the GABA(A)-benzodiazepine receptor complex functioning.     

Pharmacokinetics of steroidal muscle relaxants in isolated perfused rat liver.

Both in humans and animals hepatic elimination is an important factor determining the duration of action of non-depolarizing neuromuscular blocking drugs. To elucidate the hepato-biliary disposition of muscle relaxants the pharmacokinetics of several structurally related but physicochemically distinct steroidal neuromuscular blocking drugs were studied in isolated perfused rat livers. Pharmacokinetics analysis with the DIFFIT computer program enabled the simultaneous fitting of independently measured perfusate disappearance and biliary excretion rate curves using a numerical approach. The hepatic disposition of the steroidal muscle relaxants could be adequately described by a three compartment model with elimination from the peripheral compartment V2 (biliary excretion) and storage in a deep compartment (V3) connected to V2. In addition, for vecuronium only slow ester hydrolysis occurring in V2 and V3 was included in the model. The lipophilicity rather than the relative mobility of the muscle relaxants showed a positive relationship with biliary clearance (Cl20) and the initial hepatic uptake (Cl12), indicating that hepato-biliary transport of these organic cations is highly dependent on the hydrophobic character of the compounds. In addition, net hepatic uptake of the steroidal cations was influenced markedly by transport from the liver to perfusate (hepatic efflux). This hepatic efflux (k21) decreased with increasing lipophilicity. In contrast, the extent of intracellular sequestration into deep compartments, indicated by high k23/k32 ratios, seemed to be inversely related to the lipophilicity of the muscle relaxants and might explain the observed prolonged hepatic storage of some of these compounds. In combination with data from subfractionation studies the results indicate that the pharmacokinetic analysis of the hepatic disposition of steroidal muscle relaxants may be used to evaluate actual transport phenomena participating in the hepatic disposition of these drugs.     

Stress-induced hyperthermia and anxiety: pharmacological validation

When mammals, including man, are confronted with a stressful event, their core body temperature rises, stress-induced hyperthermia. In mice, the stress-induced hyperthermia procedure has been developed to measure antistress or anxiolytic-like effects of psychoactive drugs. Group-housed and singly housed versions of the stress-induced hyperthermia generate comparable results. Because the number of animals needed to perform an experiment is much lower in the singly housed versus the group-housed procedure, the former is the test of choice for pharmacological testing. A typical stress-induced hyperthermia test starts with an injection 60 min before the first rectal temperature measurement (T(1)), followed by a second temperature measurement (T(2)) 10-15 min later. The difference DeltaT (=T(2)-T(1)) is the stress-induced hyperthermia. The procedure also measures the intrinsic activity of drugs on the basal body temperature and DeltaT is relatively independent from the intrinsic temperature effects of drugs. Anxiolytic drugs (benzodiazepines, 5-HT(1A) receptor agonists, alcohol) reduce DeltaT suggestive of anxiolytic-like effects. Because the parameter measured for anxiety in the stress-induced hyperthermia procedure is not dependent on locomotor activity, like in almost all other anxiety tests, the stress-induced hyperthermia procedure is an attractive addition to tests in the anxiety field. Because the stress-induced hyperthermia is also present with a comparable pharmacological profile in females, this procedure has a wide species and gender validity. The procedure was applied in various genetically modified mice [5-HT(1A) and 5-HT(1B) receptor knockout (KO) mice and corticotropin-releasing hormone overexpressing (CRH-OE) mice] to study phenotypic influences of the various mutations on aspects of anxiety. The stress-induced hyperthermia test in singly housed male and female mice appears a useful and extremely simple test to measure effects of drugs on certain aspects of anxiety or to help to determine phenotypic differences in mutant mice.     

The antiphospholipid antibody dilemma

Clinical Rheumatology - In evaluating the literature, we have to be aware of some important drawbacks of most studies: 1) the relation between aPLab and thrombosis has not yet been proven in...     

Effective collaboration between marginal metallophilic macrophages and CD8+ dendritic cells in the generation of cytotoxic T cells

The spleen is the lymphoid organ that induces immune responses toward blood-borne pathogens. Specialized macrophages in the splenic marginal zone are strategically positioned to phagocytose pathogens and cell debris, but are not known to play a role in the activation of T-cell responses. Here we demonstrate that splenic marginal metallophilic macrophages (MMM) are essential for cross-presentation of blood-borne antigens by splenic dendritic cells (DCs). Our data demonstrate that antigens targeted to MMM as well as blood-borne adenoviruses are efficiently captured by MMM and exclusively transferred to splenic CD8⁺ DCs for cross-presentation and for the activation of cytotoxic T lymphocytes. Depletion of macrophages in the marginal zone prevents cytotoxic T-lymphocyte activation by CD8⁺ DCs after antibody targeting or adenovirus infection. Moreover, we show that tumor antigen targeting to MMM is very effective as antitumor immunotherapy. Our studies point to an important role for splenic MMM in the initial steps of CD8⁺ T-cell immunity by capturing and concentrating blood-borne antigens and the transfer to cross-presenting DCs which can be used to design vaccination strategies to induce antitumor cytotoxic T-cell immunity.     

Chronic paroxetine treatment does not affect sexual behavior in hormonally sub-primed female rats despite 5-HT₁(A) receptor desensitization

IntroductionSelective serotonin reuptake inhibitors (SSRIs) cause sexual dysfunctions in humans. However, because SSRIs are used to treat depression, it is unclear whether the problems are caused by the drug, by the depression itself, or an interaction between both.AimThe present study investigated the effects of chronic paroxetine treatment on sexual behavior in female rats. Furthermore, we tested whether 5‐hydroxytryptamine (5‐HT)_1A receptors were desensitized in these females.MethodsOvariectomized female rats, either sub‐primed with estradiol or fully primed with estradiol and progesterone, were tested in a paced mating test. Proceptive (darting and hopping), receptive (lordosis), and paced mating‐related (percentages of exits and contact‐return latencies) behaviors were quantified during the course of 56 days of chronic paroxetine treatment (10 mg/kg and 20 mg/kg per day). The 5‐HT_1A/5‐HT₇ receptor agonist (±)‐8‐hydroxy‐2‐(dipropylamino)tetralin hydrobromide ((±)8‐OH‐DPAT) alone and in combination with the selective 5‐HT_1A receptor antagonist WAY‐100635 was administered to study putative 5‐HT_1A desensitization in the same females.Main Outcome MeasuresProceptive, receptive, and paced mating behaviors were quantified.ResultsAcute and chronic paroxetine treatment did not change proceptive and receptive behaviors in both sub‐primed and fully primed female rats. In all groups, (±)8‐OH‐DPAT showed a clear dose‐dependent inhibition of sexual behaviors in vehicle‐treated females and a right‐shifted dose–response effect in the paroxetine‐treated rats. WAY‐100635 attenuated the inhibiting effect of the 5‐HT_1A receptor agonist in all females. These data suggest 5‐HT_1A receptor desensitization after chronic paroxetine treatment.ConclusionsChronic paroxetine treatment does not cause sexual side effects in sub‐ or fully hormonally primed female rats. Furthermore, chronic treatment causes adaptive changes in the serotonin system such as desensitization of 5‐HT_1A receptors, which may counteract the inhibiting effects of increased extracellular serotonin levels in the chronic paroxetine‐treated rats. Snoeren EMS, Refsgaard LK, Waldinger MD, Olivier B, and Oosting RS. Chronic paroxetine treatment does not affect sexual behavior in hormonally sub‐primed female rats despite 5‐HT_1A receptor desensitization.     

Umbilical cord: factors which influence the separation time.

The separation time of the umbilical cord was studied in 98 healthy Indonesian newborns with the aim of determining the normal time of separation and to evaluate factors which may influence it. The authors looked for a relationship between cord separation and sex, birthweight, gestational age, parity of the mother and nutrition of the newborn. Mean separation time was 10.9 days (S.D. 3: range 5-23 days). None of the factors analysed had a statistically significant influence. Cord care consisted of triple dye; no umbilical infections were found.     

High-resolution copy number analysis of paraffin-embedded archival tissue using SNP BeadArrays

High-density SNP microarrays provide insight into the genomic events that occur in diseases like cancer through their capability to measure both LOH and genomic copy numbers. Where currently available methods are restricted to the use of fresh frozen tissue, we now describe the design and validation of copy number measurements using the Illumina BeadArray platform and the application of this technique to formalin-fixed, paraffin-embedded (FFPE) tissue. In fresh frozen tissue from a set of colorectal tumors with numerous chromosomal aberrations, our method measures copy number patterns that are comparable to values from established platforms, like Affymetrix GeneChip and BAC array-CGH. Moreover, paired comparisons of fresh frozen and FFPE tissues showed nearly identical patterns of genomic change. We conclude that this method enables the use of paraffin-embedded material for research into both LOH and numerical chromosomal abnormalities. These findings make the large pathological archives available for genomic analysis, which could be especially relevant for hereditary disease where fresh material from affected relatives is rarely available.