Effect of COMT Val158Met polymorphism on personality traits and educational attainment in a longitudinal population representative study

The COMT Val158Met polymorphism has been associated with anxiety and affective disorders, but its effect on anxiety-related personality traits varies between studies. Our purpose was to investigate the effect of COMT Val158Met on personality traits from adolescence to young adulthood in a population representative Caucasian birth cohort. Also its association with educational attainment and anxiety and mood disorders by the age 25 were examined. This analysis is based on the older cohort of the Estonian Children Personality Behavior and Health Study (original number of subjects 593). The personality traits were assessed when the participants were 15, 18 and 25 years old. COMT Val158Met had an effect on Neuroticism in females by age 25 (p = 0.001, Bonferroni-corrected for five traits), whereas female Val homozygotes scored the highest. In addition, the Conscientiousness scores of subjects with Val/Val genotype were decreasing in time, being the lowest by the age 25 (p = 0.006, Bonferroni-corrected for five traits). By the age 25, males with the Val/Met genotype had mainly secondary or vocational education, whereas female heterozygotes mostly had obtained or were obtaining university education. COMT Val158Met was not associated with anxiety or mood disorders in either gender. These results suggest that genes affecting dopamine system are involved in the development of personality traits and contribute to educational attainment.     

Stress-protective Action of β-Phenyl(GABA): Involvement of Central and Peripheral Type Benzodiazepine Binding Sites

Forced swimming stress caused a significant increase in the density of central type benzodiazepine binding sites in rat cerebral cortex and hippocampus. The number of peripheral type benzodiazepine binding sites was also enhanced on blood platelets. The affinity of neither central nor peripheral type benzodiazepine binding sites was changed considerably after swimming stress. Pretreatment of rats with β-(phenyl)GABA (100 mg/kg), a GABA_B agonist, almost completely eliminated the described changes of the both types of benzodiazepine binding sites caused by swimming stress. In an elevated plus-maze model of anxiety β-(phenyl)GABA itself was inactive but like diazepam effectively counteracted the behavioural effects of DMCM, a β-carboline derivative with anxiogenic properties. The possible involvement of benzodiazepine receptors in the mechanism of action of β-(phenyl)GABA is discussed.     

Self-mixing in a diode laser as a method for cardiovascular diagnostics

Our aim is the development of a simple optical method for pulse wave profile, pulse wave delay time, and blood flow measurement. The method is based on recording the Doppler frequency shift related to a moving target--blood vessel walls or small particles. The Doppler signal is detected using the self-mixing that occurs in the diode laser cavity when radiation scatters back from the moving target into the laser and interferes with the field inside. Two different ways can be simultaneously used for the self-mixing signal extraction: a photodiode accommodated in the rear facet of the diode laser package and a resistor from the laser pump current. An experimental device with a pigtail laser diode is developed that is able to detect the pulsation of major arteries with potentially useful information, including the pulse wave profile and the pulse wave delay time. The pulse wave delay time in different regions of the human body is measured relative to the electrocardiogram (ECG) signal. Also the flow velocity of a liquid suspension containing particles the size of erythrocytes (equivalent to blood flow) is measured. Registered signals are stored after digitalization and preprocessed using LabView for a Windows environment. The described device has the application of the self-mixing method and highlights significant advantages of simplicity, compactness, and robustness as well as the self-aligning and self-detecting abilities of such method, compared with the use of conventional interferometric method.     

Evidence for involvement of neuropeptide Y receptors in the regulation of food intake: studies with Y1-selective antagonist BIBP3226

1. Experiments were conducted to evaluate the effects of the novel non-peptide neuropeptide Y Y₁ receptor antagonist, BIBP3226 (N²-(diphenylacetyl)-N-[(4-hydroxy-phenyl)methyl]-D-arginine amide) on spontaneous, fasting-induced and NPY-induced food intake in rats. In addition to consumption of regular chow, the effects of BIBP3226 on consumption of highly palatable sweetened mash were monitored in a 1 h test on first exposure and after familiarization with novel food.
2. BIBP3226 (10.0 nmol, i.c.v.) had no effect on the consumption of regular chow, but reduced significantly the intake of highly palatable diet and the food intake stimulated by fasting (24 h). Neuropeptide Y (NPY, 1.0 nmol, i.c.v.) significantly increased the consumption of regular rat chow. This orexigenic effect of NPY was blocked by BIBP3226 (10.0 nmol, administered i.c.v. 5 min before NPY) at 30  min and 4  h, but not at 1 and 2  h. When animals were pretreated with diazepam (0.5 mg kg⁻¹, i.p., 20 min before NPY), BIBP3226 failed to suppress NPY-induced feeding.
3. An NPY Y₁ and Y₃ receptor agonist, [Leu³¹,Pro³⁴]NPY and a Y₅ receptor agonist human peptide YY_3–36 (hPYY_3–36, both 30 pmol), microinjected into the paraventricular nucleus of the hypothalamus (PVN) increased the consumption of regular rat chow. BIBP3226 (0.4 nmol, into the PVN) completely blocked the stimulatory effect of [Leu³¹,Pro³⁴]NPY but not that of hPYY_3–36. BIBP3226 (0.4 nmol) alone failed to modify the consumption of the regular chow. Higher doses of BIBP3226 (1.0 and 2.0 nmol) injected into the vicinity of the PVN reduced the consumption of the sweetened mash.
4. These results suggest that both the NPY Y₁ and Y₅ receptors in the PVN are involved in the regulation of food intake. The stimulatory effect of exogenous NPY is probably mediated through an NPY receptor subtype that is not identical with the Y₁ receptor (possibly Y₅ receptor). However, the NPY Y₁ receptors may mediate the effect of endogenous NPY in conditions of increased energy demand or on intake of highly palatable diets.

     

Cerebral oxidative metabolism in rats with high and low exploratory activity

To reveal brain regions most significantly related to individual differences in exploratory behaviour, oxidative metabolism was measured by cytochrome c oxidase histochemistry in 2 months old Wistar rats with persistently high (HE) or low (LE) exploratory activity in a novel environment. LE-rats had significantly higher levels of oxidative metabolism in dorsal raphe and inferior colliculi. In contrast, HE-rats had higher metabolic activity in entorhinal cortex. In conclusion, rats with different exploratory styles differ in underlying cerebral activity as measured via oxidative metabolism in regions implicated in defensive behaviours and cognitive processing of sensory stimuli.