The association of genetic variation in CACNA1C with resting-state functional connectivity in youth bipolar disorder

Pon1 and Sult1a1 Polymorphisms and Breast Cancer Among Young Women in Brazil

Purpose: To investigate the association of genetic polymorphisms Gln192Arg and Leu55Met of Paraoxonase 1 (PON1) gene, and Arg213His of Sulfotransferase 1A1 (SUT1A1) gene with occurrence of breast cancer among young women living in Rio de Janeiro city. Methods: This is a hospital-based case-control study including 265 women aged 18-35 years, diagnosed with breast cancer at National Cancer Institute; and 277 controls in the same age group selected among women patients and companions of three general hospitals from Rio de Janeiro public health network. Polymorphisms genotyping was performed using the PCR-RFLP technique. Results: For PON1 gene, breast cancer women had a greater chance of being homozygote for Leu55Met polymorphism (ORadjusted = 1.42, 95% CI= 0.67-3.00, recessive model) and a lower chance of having at least one allele of Gln192Arg polymorphism (ORadjusted = 0.75, 95% CI = 0.50-1.13, dominant model), but without statistical significance. Accordingly, frequency of the haplotype Met55/Arg192 was lower among breast cancer women, but no statistically significant association was observed (ORadjusted = 0.85; 95% CI = 0.48-1.51). SULT1A1 His/His genotype was significantly associated with a protective effect for breast cancer (OR adjusted = 0.51, 95% CI = 0.28-0.91, recessive model). Conclusion: Arg213His polymorphism of SUT1A1 gene showed a protective effect against breast cancer among Brazilian young women. More studies with different designs are needed to understand the role of PON1 and SULT1A1 polymorphisms in breast cancer development in young Brazilian women.

Sex-Specific Mechanisms Underlie Long-Term Potentiation at Hippocampus→Medium Spiny Neuron Synapses in the Medial Shell of the Nucleus Accumbens

Sex differences have complicated our understanding of the neurobiological basis of many behaviors that are key for survival. As such, continued elucidation of the similarities and differences between sexes is necessary to gain insight into brain function and vulnerability. The connection between the hippocampus (Hipp) and nucleus accumbens (NAc) is a crucial site where modulation of neuronal activity mediates reward-related behavior. Our previous work demonstrated that long-term potentiation (LTP) of Hipp→NAc synapses is rewarding, and mice can establish learned associations between LTP of these synapses and the contextual environment in which LTP occurred. Here, we investigated sex differences in the mechanisms underlying Hipp→NAc LTP using whole-cell electrophysiology and pharmacology. We observed similarities in basal synaptic strength between males and females and found that LTP occurs postsynaptically with similar magnitudes in both sexes. However, key sex differences emerged as LTP in males required NMDA receptors (NMDAR), whereas LTP in females utilized an NMDAR-independent mechanism involving L-type voltage-gated Ca2+ channels (VGCCs) and estrogen receptor α (ERα). We also uncovered sex-similar features as LTP in both sexes depended on CaMKII activity and occurred independently of dopamine-1 receptor (D1R) activation. Our results have elucidated sex-specific molecular mechanisms for LTP in an integral pathway that mediates reward-related behaviors, emphasizing the importance of considering sex as a variable in mechanistic studies. Continued characterization of sex-specific mechanisms underlying plasticity will offer novel insight into the neurophysiological basis of behavior, with significant implications for understanding how diverse processes mediate behavior and contribute to vulnerability to developing psychiatric disorders.

Sex-specific mechanisms underlie long-term potentiation at hippocampus-nucleus accumbens synapses

Sex differences have complicated our understanding of the neurobiological basis of many behaviors that are key for survival. As such, continued elucidation of the similarities and differences between sexes is necessary in order to gain insight into brain function and vulnerability. The connection between the hippocampus (Hipp) and nucleus accumbens (NAc) is a crucial site where modulation of neuronal activity mediates reward-related behavior. Our previous work demonstrated that long-term potentiation (LTP) of Hipp-NAc synapses is rewarding, and that mice can make learned associations between LTP of these synapses and the contextual environment in which LTP occurred. Here, we investigate sex differences in the mechanisms underlying Hipp-NAc LTP using whole-cell electrophysiology and pharmacology. We found that males and females display similar magnitudes of Hipp-NAc LTP which occurs postsynaptically. However, LTP in females requires L-type voltage-gated Ca 2+ channels (VGCC) for postsynaptic Ca 2+ influx, while males rely on NMDA receptors (NMDAR). Additionally, females require estrogen receptor α (ERα) activity for LTP while males do not. These differential mechanisms converge as LTP in both sexes depends on CAMKII activity and occurs independently of dopamine-1 receptor (D1R) activation. Our results have elucidated sex-specific molecular mechanisms for LTP in an integral excitatory pathway that mediates reward-related behaviors, emphasizing the importance of considering sex as a variable in mechanistic studies. Continued characterization of sex-specific mechanisms underlying plasticity will offer novel insight into the neurophysiological basis of behavior, with significant implications for understanding how diverse processes mediate behavior and contribute to vulnerability to developing psychiatric disorders.

SIGNIFICANCE STATEMENT

Strengthening of Hipp-NAc synapses drives reward-related behaviors. Male and female mice have similar magnitudes of long-term potentiation (LTP) and both sexes have a predicted postsynaptic locus of plasticity. Despite these similarities, we illustrate here that sex-specific molecular mechanisms are used to elicit LTP. Given the bidirectional relationship between Hipp-NAc synaptic strength in mediating reward-related behaviors, the use of distinct molecular mechanisms may explain sex differences observed in stress susceptibility or response to rewarding stimuli. Discovery and characterization of convergent sex differences provides mechanistic insight into the sex-specific function of Hipp-NAc circuitry and has widespread implications for circuits mediating learning and reward-related behavior.

Screening, Genetic Variants, and Bipolar Disorders: Can Useful Hypotheses Arise from the Sum of Partial Failures?

Bipolar disorder (BD) is a relevant public health issue, therefore accurate screening tools could be useful. The objective of this study is to verify the accuracy of the Mood Disorder Questionnaire (MDQ) and genetic risk as screeners, and their comparison in terms of reliability. Older adults (N = 61, ≥60 years) received a clinical psychiatric evaluation, the MDQ, and were evaluated according to the presence of the genetic variant RS1006737 of CACNA1C. MDQ+ versus the diagnosis of BD as a gold standard shows a sensitivity of 0.286 (Cl 95% 0.14-0.39); a specificity of 0.925 (Cl 95% 0.85-0.08); a predictive positive value (PPV) of 0.667 (Cl 95% 0.33-0.91); and a predictive negative value (PNV) of 0.702 (Cl 95% 0.65-0.75). The positivity for the variant RS1006737 of the CACNA1C against the diagnosis of BD as a gold standard shows a sensitivity of 0.750 (Cl 95% 0.55-0.90); a specificity of 0.375 (Cl 95% 0.28-0.45); a PPV of 0.375 (Cl 95% 0.28-0.45); and a PNV of 0.750 (Cl 95% 0.55-0.90). The reliability between the MDQ+ and positivity for the variant RS1006737 of the CACNA1C was very low (K = -0.048, Cl 95% -0.20-0.09). The study found that both the genetic and the paper and pencil test were quite accurate, but were not reliable in case finding. In fact, despite some validity, albeit specular (in the case of a positive genetic test, the probability of having the disorder is very high, whereas in the case of a negative score on the paper and pencil test, the probability of not having the disorder is very high), the unreliability of the two tests (i.e., they certainly do not measure the same underlying dimension) opens the door to the need for an interpretation and the possibility of a synergistic use for screening. From a heuristic perspective, which obviously requires all of the necessary verifications, this study seems to suggest the hypothesis that a condition of hyperactivation common to disorders and stress conditions, and identified by a positive score on the MDQ (which is common to BD, post-traumatic stress disorder (PTSD), and anxiety disorders and whose genetic basis has not yet been clarified) can trigger BD in people with a predisposition to hyperactivity (i.e., in people with the condition identified by the analyzed genetic variant).