Sex steroid hormone synthesis, metabolism, and the effects on the mammalian olfactory system

Impairment of olfactory identification ability in ultra-high risk for psychosis and drug-naïve first episode psychosis

OBJECTIVE

Patients with psychotic diseases have been reported to exhibit abnormalities in their olfactory discrimination. These alterations have also been identified in people at high genetic or clinical risk for psychosis, suggesting olfactory discrimination dysfunction may be a potential risk factor for developing psychosis. Thus, the purpose of our study is to explore the difference in olfactory discrimination ability in the prosal stage and early stage of psychosis and to explore the potential risk factor of developed psychosis.

METHODS

We compared olfactory identification and cognitive function in 89 ultra-high-risk (UHR) individuals, 103 individuals with Drug-naïve first-episode schizophrenia (FES), 81 genetic high-risk (GHR) individuals, and 97 healthy controls (HC). Additionally, we compared olfactory identification and cognitive function between two groups; UHR individuals who later transitioned to psychosis (UHR-T; n = 33) and those who did not transition (UHR-NT; n = 42)). Furthermore, we analyzed the correlations between olfactory discrimination ability and cognitive function and symptoms and compared the olfactory function between men and women.

RESULTS

Patients with first-episode schizophrenia (FES) and those at ultra-high risk (UHR) for psychosis exhibited more significant deficits in olfactory identification than healthy controls (HC), while no differences in olfactory identification dysfunction were observed between the genetic high risk (GHR) and HC groups. Notably, individuals in the UHR group who later developed psyhchosis displayed a steeper marked decline in their baseline olfactory identification ability than that of those in the UHR group who did not develop psychosis. Cognitive dysfunction is widely observed in both the FES and UHR groups, with a distinct correlation identified between olfactory discrimination function and cognitive performance. Finally, overall, women exhibit significantly superior olfactory function than men.

CONCLUSION

In conclusion, these findings suggest that impairment of olfactory identification exists in the early stage of psychosis. Olfactory identification dysfunction may therefore be a potential marker of predicting the transition to schizophrenia.

Role of neuroestrogens in the regulation of social behaviors - From social recognition to mating

In this mini-review, we summarize the brain distribution of aromatase, the enzyme catalyzing the synthesis of estrogens from androgens, and the mechanisms responsible for regulating estrogen production within the brain. Understanding this local synthesis of estrogens by neurons is pivotal as it profoundly influences various facets of social behavior. Neuroestrogen action spans from the initial processing of socially pertinent sensory cues to integrating this information with an individual's internal state, ultimately resulting in the manifestation of either pro-affiliative or - aggressive behaviors. We focus here in particular on aggressive and sexual behavior as the result of correct individual recognition of intruders and potential mates. The data summarized in this review clearly point out the crucial role of locally synthesized estrogens in facilitating rapid adaptation to the social environment in rodents and birds of both sexes. These observations not only shed light on the evolutionary significance but also indicate the potential implications of these findings in the realm of human health, suggesting a compelling avenue for further investigation.

Towards detection of cancer biomarkers in human exhaled air by transfer-learning-powered analysis of odor-evoked calcium activity in rat olfactory bulb

Detection of volatile organic compounds in exhaled air is a promising approach to non-invasive and scalable gastric cancer screening. This work proposes a new approach for the detection of volatile organic compounds by analyzing odor-evoked calcium responses in the rat olfactory bulb. We estimate the feasibility of gastric cancer biomarker detection added to the exhaled air of healthy participants. Our detector consists of a convolutional encoder and a similarity-based classifier over encoder outputs. To minimize overfitting on a small available training set, we involve a pre-training where the encoder is trained on synthetic data representing spatiotemporal patterns similar to real calcium responses in the olfactory bulb. We estimate the classification accuracy of exhaled air samples by matching their encodings with encodings of calibration samples of two classes: 1) exhaled air and 2) a mixture of exhaled air with the cancer biomarker. On our data, the accuracy increased from 0.68 on real data up to 0.74 if pre-training on synthetic data is involved. Our work is focused on proving the feasibility of proposed new approach rather than on comparing its efficiency with existing methods. Such detection is often performed with an electronic nose, but its output becomes unstable over time due to a sensor drift. In contrast to the electronic nose, rats can robustly detect low concentrations of biomarkers over lifetime. The feasibility of gastric cancer biomarker detection in exhaled air by bio-hybrid system is shown. Pre-training of neural models for images analysis increases the accuracy of detection.

Pheromone Perception in Fish: Mechanisms and Modulation by Internal Status

Pheromones are chemical signals that facilitate communication between animals, and most animals use pheromones for reproduction and other forms of social behavior. The identification of key ligands and olfactory receptors used for pheromonal communication provides insight into the sensory processing of these important cues. An individual's responses to pheromones can be plastic, as physiological status modulates behavioral outputs. In this review, we outline the mechanisms for pheromone sensation and highlight physiological mechanisms that modify pheromone-guided behavior. We focus on hormones, which regulate pheromonal communication across vertebrates including fish, amphibians, and rodents. This regulation may occur in peripheral olfactory organs and the brain, but the mechanisms remain unclear. While this review centers on research in fish, we will discuss other systems to provide insight into how hormonal mechanisms function across taxa.