Evidence that the N-methyl-D-aspartate subunit 1 receptor gene (GRIN1) confers susceptibility to bipolar disorder.

There is evidence for the involvement of glutamatergic transmission in the pathogenesis of major psychoses. The two most commonly used mood stabilizers (ie lithium and valproate) have been found to act via the N-methyl-D-aspartate receptor (NMDAR), suggesting a specific role of NMDAR in the pathogenesis of bipolar disorder (BP). The key subunit of the NMDAR, named NMDA-1 receptor, is coded by a gene located on chromosome 9q34.3 (GRIN1). We tested for the presence of linkage disequilibrium between the GRIN1 (1001-G/C, 1970-A/G, and 6608-G/C polymorphisms) and BP. A total of 288 DSM-IV Bipolar I, Bipolar II, or schizoaffective disorder, manic type, probands with their living parents were studied. In all, 73 triads had heterozygous parents for the 1001-G/C polymorphism, 174 for the 1970-A/G, and 48 for the 6608-G/C. These triads were suitable for the final analyses, that is, the transmission disequilibrium test (TDT) and the haplotype-TDT. For the 1001-G/C and the 6608-G/C polymorphisms, we found a preferential transmission of the G allele to the affected individuals (chi(2)=4.765, df=1, P=0.030 and chi(2)= 8.395, df=1, P=0.004, respectively). The 1001G-1970A-6608A and the 1001G-1970A-6608G haplotypes showed the strongest association with BP (global chi(2)=14.12, df=4, P=0.007). If these results are replicated there could be important implications for the involvement of the GRIN1 in the pathogenesis of BP. The role of the gene variants in predicting the response to mood stabilizers in BP should also be investigated.

Use of slow-release melatonin in treatment-resistant depression.

OBJECTIVE: To examine antidepressant augmentation with and hypnotic effects of slow-release melatonin (SR-melatonin) in patients with treatment-resistant depression. DESIGN: Open-label trial. SETTING: Tertiary care outpatient depression clinic. PATIENTS: Nine outpatients who had failed to respond to 2 or more 8-week trials of antidepressant medication. INTERVENTIONS: Patients received SR-melatonin 5 mg per day for the first 2 weeks and 10 mg per day for the final 2 weeks, in addition to their antidepressant medication. OUTCOME MEASURES: Structured Clinical Interview for DSM-IV, Axis 1 Disorders, Hamilton Rating Scale for Depression (HRSD), Beck Depression Inventory, Response Style Questionnaire, sleep and fatigue measures. RESULTS: One patient was excluded after 1 week because of the development of a mixed affective state. In the remaining 8 patients there was a 20% mean decrease in HRSD scores after 4 weeks of treatment, with no individual achieving an improvement of 50% or more. There was a 36% decrease on the 3-item HRSD related to insomnia, with 4 of 8 patients showing at least a 50% improvement on this measure. The greatest decrease in insomnia occurred during the last 2 weeks of the study, following the increase in dosage to 10 mg per day of SR-melatonin. Patients also reported significantly lower levels of fatigue post-treatment. CONCLUSIONS: SR-melatonin may be a useful adjunct for sleep, but does not substantially augment existing antidepressant therapies in some patients with treatment-resistant depression.

Stopped-flow investigation of nitrated bovine neurophysin monomer binding to oxytocin.

By use of stopped-flow kinetic data, we have measured the kinetics of mononitrated neurophysin I monomer binding to oxytocin. The association constant was 1.3(+/-0.3) x 10(5) M-1s-1 and the dissociation rate constant was 2.0(+/-0.5)s-1 for protonated oxytocin binding. Both rates are significantly slower than those observed for neurophysin dimer. These data suggest that the binding process by which the monomer binds oxytocin is not identical to that of dimer.

Thermodynamics and kinetics of bovine neurophysins binding to small peptide analogues of oxytocin and vasopressin.

Thermodynamic binding constants for the interactions of mononitrated neurophysins with oxytocin, vasopressin, and peptide analogues of the hormones were determined by using a spectrophotometric titration technique. The data were fit to a binding model which included all known interactions in these systems. From an examination of the free energies for the binding reaction, we concluded that residues 1-3 contribute 84% of the binding energy for formation of the neurophysin dimer mono complex and 79% for the formation of the bis complex. Rate constants for complex formation and dissociation with native bovine neurophysin were determined by using temperature-jump relaxation. The association rate constants for neurophysin dimer binding to oxytocin, vasopressin, and the peptide analogues were all in the range of 1.3 X 10(6) M-1 s-1 for mono complexation and 1.5 X 10(6) M-1 s-1 for bis complexation. Thus, formation rate constants are identical for both mono and bis complexation, and no significant differences exist between formation constants for hormones and peptides. On the other hand, a clear distinction in dissociation rate constants is apparent when one compares the hormones (kr = 4 to 16 s-1) with the peptide analogues (kr = 54 to 182 s-1). There is rougly a tenfold increase in overall dissociation rate constant when one compares the peptides to the hormones. From these data, we conclude that the rate-determining step in the association reaction involves the first two or three residues on the hormone. After the initial binding takes place, only with intact hormone, i.e., oxytocin or vasopressin, can additional bonding interactions in the complex take place. These additional interactions are reflected in the slower off-rate of the hormone complexes relative to the peptide complexes.

Studies on equine immunoglobulins. IV. Immunoglobulins of the donkey.

Donkey IgGa was isolated in purified form from normal and immune donkey sera by column chromatography on DEAE-cellulose. Isolated donkey IgGa and mixtures of (IgGa+IgGb) were used as antigens to prepare rabbit reagents specific for equine IgGa or IgGb. Antibodies present in sera obtained from a single donkey at various times during the course of hyperimmunization with BSA were isolated by immuno-adsorption. The class or subclass of immunoglobulins present among isolated, donkey anti-BSA antibodies was determined by use of specific rabbit anti-equine immunoglobulin reagents. The homologues of horse IgGa, IgGb, IgGc and IgA were identified in normal donkey, mule, hinny and zebra serum.