Edward I. Ginns

Vasopressin V1b receptor knockout reduces aggressive behavior in male mice

Increased aggression is commonly associated with many neurological and psychiatric disorders. Current treatments are largely empirical and are often accompanied by severe side effects, underscoring the need for a better understanding of the neural bases of aggression. Vasopressin, acting through its 1a receptor subtype, is known to affect aggressive behaviors. The vasopressin 1b receptor (V1bR) is also expressed in the brain, but has received much less attention due to a lack of specific drugs. Here we report that mice without the V1bR exhibit markedly reduced aggression and modestly impaired social recognition. By contrast, they perform normally in all the other behaviors that we have examined, such as sexual behavior, suggesting that reduced aggression and social memory are not simply the result of a global deficit in sensorimotor function or motivation. Fos-mapping within chemosensory responsive regions suggests that the behavioral deficits in V1bR knockout mice are not due to defects in detection and transmission of chemosensory signals to the brain. We suggest that V1bR antagonists could prove useful for treating aggressive behavior seen, for example, in dementias and traumatic brain injuries.

Deficiency in Mouse Oxytocin Prevents Milk Ejection,but not Fertility or Parturition

Oxytocin is a nonapeptide hormone that participates in the regulation of parturition and lactation. It has also been implicated in various behaviors, such as mating and maternal, and memory. To investigate whether or not oxytocin (OT) is essential for any of these functions, we eliminated, by homologous recombination, most of the first intron and the last two exons of the OT gene in mice. Those exons encode the neurophysin portion of the oxytocin preprohormone which is hypothesized to help in the packaging and transport of OT. The homozygous mutant mice have no detectable neurophysin or processed oxytocin in the paraventricular nucleus, supraoptic nucleus or posterior pituitary. Interestingly, homozygous mutant males and females are fertile and the homozygous mutant females are able to deliver their litters. However, the pups do not successfully suckle and die within 24 h without milk in their stomachs. OT injection into the dams restores the milk ejection in response to suckling. These results indicate an absolute requirement for oxytocin for successful milk ejection, but not for mating, parturition and milk production, in mice.

A Mutation in the Human Glucocerebrosidase Gene in Neuronopathic Gaucher's Disease

To search for a genetic marker for type 2 Gauchers disease (acute neuronopathic form), we compared the nucleotide sequence of a cloned glucocerebrosidase gene from a patient with Gauchers disease with a normal gene. We found only a single base substitution (T----C) in exon X. This mutation results in the substitution of proline for leucine in position number 444 and produces a new cleavage site for the NciI restriction endonuclease. We analyzed NciI enzymatic digests of genomic DNA from 20 patients with type 1, 5 with type 2, and 11 with type 3 Gauchers disease, and 29 normal controls for a restriction-fragment-length polymorphism (RFLP). Four of 5 patients with type 2 disease and all 11 with type 3 disease had at least one allele with the mutation. Two of 5 patients with type 2 disease and 7 of 11 with type 3 were homozygous for this mutation. Only 4 of 20 patients with type 1 Gauchers disease had the mutant allele and were heterozygous for it. None of the 29 normal controls had the mutant allele. The high frequency of this mutation (444leucine----proline) in patients with neuronopathic Gauchers disease, detectable by the NciI RFLP, may be of value in the identification of patients who will have the neurologic sequelae of Gauchers disease.

Consequences of beta-glucocerebrosidase deficiency in epidermis. Ultrastructure and permeability barrier alterations in Gaucher disease.

Hydrolysis of glucosylceramide by beta-glucocerebrosidase results in ceramide, a critical component of the intercellular lamellae that mediate the epidermal permeability barrier. A subset of type 2 Gaucher patients displays ichthyosiform skin abnormalities, as do transgenic Gaucher mice homozygous for a null allele. To investigate the relationship between glucocerebrosidase deficiency and epidermal permeability barrier function, we compared the stratum corneum (SC) ultrastructure, lipid content, and barrier function of Gaucher mice to carrier and normal mice, and to hairless mice treated topically with bromoconduritol B epoxide (BrCBE), an irreversible inhibitor of glucocerebrosidase. Both Gaucher mice and BrCBE-treated mice revealed abnormal, incompletely processed, lamellar body-derived sheets throughout the SC interstices, while transgenic carrier mice displayed normal bilayers. The SC of a severely affected type 2 Gauchers disease infant revealed similarly abnormal ultrastructure. Furthermore, the Gaucher mice demonstrated markedly elevated transepidermal water loss (4.2 +/- 0.6 vs < 0.10 g/m2 per h). The electron-dense tracer, colloidal lanthanum, percolated between the incompletely processed lamellar body-derived sheets in the SC interstices of Gaucher mice only, demonstrating altered permeability barrier function. Gaucher and BrCBE-treated mice showed < 1% and < 5% of normal epidermal glucocerebrosidase activity, respectively, and the epidermis/SC of Gaucher mice demonstrated elevated glucosylceramide (5- to 10-fold), with diminished ceramide content. Thus, the skin changes observed in Gaucher mice and infants may result from the formation of incompetent intercellular lamellar bilayers due to a decreased hydrolysis of glucosylceramide to ceramide. Glucocerebrosidase therefore appears necessary for the generation of membranes of sufficient functional competence for epidermal barrier function.

Molecular Determinants of Dysregulated GABAergic Gene Expression in the Prefrontal Cortex of Subjects with Schizophrenia

BACKGROUND Prefrontal deficits in gamma-aminobutyric acid (GABA)ergic gene expression, including neuropeptide Y (NPY), somatostatin (SST), and parvalbumin (PV) messenger RNAs (mRNAs), have been reported for multiple schizophrenia cohorts. Preclinical models suggest that a subset of these GABAergic markers (NPY/SST) is regulated by brain-derived neurotrophic factor (BDNF), which in turn is under the inhibitory influence of small noncoding RNAs. However, it remains unclear if these mechanisms are important determinants for dysregulated NPY and SST expression in prefrontal cortex (PFC) of subjects with schizophrenia. METHODS Using a postmortem case-control design, the association between BDNF protein, NPY/SST/PV mRNAs, and two BDNF-regulating microRNAs (miR-195 and miR-30a-5p) was determined in samples from the PFC of 20 schizophrenia and 20 control subjects. Complementary studies were conducted in cerebral cortex of mice subjected to antipsychotic treatment or a brain-specific ablation of the Bdnf gene. RESULTS Subjects with schizophrenia showed deficits in NPY and PV mRNAs. Within-pair differences in BDNF protein levels showed strong positive correlations with NPY and SST and a robust inverse association with miR-195 levels, which in turn were not affected by antipsychotic treatment or genetic ablation of Bdnf. CONCLUSIONS Taken together, these results suggest that prefrontal deficits in a subset of GABAergic mRNAs, including NPY, are dependent on the regional supply of BDNF, which in turn is fine-tuned through a microRNA (miRNA)-mediated mechanism.

Lack of an association between a dopamine-4 receptor polymorphism and attention-deficit/hyperactivity disorder: genetic and brain morphometric analyses

Although the etiology of attention-deficit/hyperactivity disorder (ADHD) is likely multifactorial, family,1 adoption,2 and twin studies3 suggest that genetic factors contribute significantly. Polymorphisms of the dopamine 4 receptor (DRD4) affect receptor binding,4 and one allele with seven tandem repeats in exon 3 (DRD4*7R) has been associated with ADHD.5,6 We examined this putative association in 41 children with severe ADHD and 56 healthy controls who were group matched for ethnicity and sex. The frequency of the DRD4*7R allele did not vary by diagnosis (0.220 vs 0.205 in patients and controls, respectively). Behavioral and brain anatomic MRI measures, previously found to discriminate patients from controls,7 did not differ significantly between subjects having and those lacking a DRD4*7R allele. These data do not support the reported association between DRD4*7R and the behavioral or brain morphometric phenotype associated with ADHD.

Glucosylsphingosine accumulation in tissues from patients with Gaucher disease : correlation with phenotype and genotype

Gaucher disease, the inherited deficiency of lysosomal glucocerebrosidase, presents with a wide spectrum of clinical manifestations including neuronopathic and non-neuronopathic forms. While the lipid glucosylceramide is stored in both patients with Gaucher disease and in a null allele mouse model of Gaucher disease, elevated levels of a second potentially toxic substrate, glucosylsphingosine, are also found. Using high performance liquid chromatography, glucosylsphingosine levels were measured in tissues from patients with type 1, 2, and 3 Gaucher disease. Glucosylsphingosine was measured in 16 spleen samples (8 type 1; 4 type 2; and 4, type 3) and levels ranged from 54 to 728 ng/mg protein in the patients with type 1 disease, 133 to 1200 ng/mg protein in the patients with type 2, and 109 to 1298 ng/mg protein in the type 3 samples. The levels of splenic glucosylsphingosine bore no relation to the type of Gaucher disease, the age of the patient, the genotype, nor the clinical course. In the same patients, hepatic glucosylsphingosine levels were lower than in spleen. Glucosylsphingosine was also measured in brains from 13 patients (1 type 1; 8 type 2; and 4 type 3). While the glucosylsphingosine level in the brain from the type 1 patient, 1.0 ng/mg protein, was in the normal range, the levels in the type 3 samples ranged from 14 to 32 ng/mg protein, and in the type 2 samples from 24 to 437 ng/mg protein, with the highest values detected in two fetuses with hydrops fetalis. The elevated levels found in brains from patients with neuronopathic Gaucher disease support the hypothesis that glucosylsphingosine may contribute to the nervous system involvement in these patients.

Gaucher Disease in the Neonate: A Distinct Gaucher Phenotype Is Analogous to a Mouse Model Created by Targeted Disruption of the Glucocerebrosidase Gene

ABSTRACT: A group of neonates with Gaucher disease with a particularly devastating clinical course is described. The phenotype of these infants is analogous to that of a Gaucher mouse, which was created by targeted disruption of the mouse glucocerebroside gene. Similar to the homozygous mutant mice with glucocerebrosidase deficiency, these infants present at or shortly after birth, have rapidly progressing fulminant disease, and many have associated ichthyotic skin and/or hydrops fetalis. This transgenetic mouse model of Gaucher disease has helped us to appreciate a distinct Gaucher phenotype. Potentially, as this technology is applied to create other animal models of metabolic diseases, it may enable the recognition of other, as yet unappreciated presentations of inherited disorders.

CD4 receptor binding peptides that block HIV infectivity cause human monocyte chemotaxis. Relationship to vasoactive intestinal polypeptide.

The octapeptide Ala‐Ser‐Thr‐Thr‐Thr‐Asn‐Tyr‐Thr (peptide T) and two structural analogs are potent agonists of human monocyte chemotaxis, evincing identical rank potency orders as was previously shown for their inhibition of human immunodeficiency virus (HIV) envelope binding and T cell infectivity. Chemotactic activity could be inhibited by anti‐CD4 monoclonal antibodies (Mabs), but not other mononuclear cell Mabs. The core peptide required for chemotactic activity is a pentapeptide related to the sequence Thr‐Thr‐Asn‐Tyr‐Thr. Homologous pentapeptides, identified by computer search, were detected in several other non‐HIV‐related viruses as well as the neuropeptide vasoactive intestinal polypeptide (VIP). The CD4 molecule, therefore, appears to be a recognition molecule for a small signal peptide ligand whose active sequence is a homolog of peptide T [4–8] and which may be the neuropeptide VIP.

Bone-Marrow Transplantation in Severe Gaucher's Disease

We performed allogeneic bone-marrow transplantation of normal cells in an eight-year-old patient with Type 3 Gauchers disease in an attempt to alter his progressive deterioration. The procedure resulted in complete engraftment of the enzymatically normal donor cells. Donor monocyte precursors were present in the circulation of the recipient by 28 days after transplantation. Post-transplantation beta-glucocerebrosidase activity in mononuclear white cells in peripheral blood exceeded normal levels. Despite these early results no change in Gauchers-cell infiltration of the bone marrow was noted for at least 111 days, and Gauchers cells persisted in the marrow for at least 274 days. The plasma glucocerebroside concentration ultimately returned to normal. During the post-transplantation course, until the patient died from an episode of sepsis, there was no important change in his clinical status. However, this case demonstrates that the enzymatic abnormality in hematopoietic cells in Gauchers disease is correctable by bone-marrow transplantation, leading to normalization of plasma levels of glucocerebroside. We observed the long survival of Gauchers cells, which was consistent with the lack of clinical improvement. Intervention might have been more effective earlier in the course of the disease.