Sex hormone binding globulin during an annual reproductive cycle in the hepatopancreas and ovary of pejerrey (Odontesthes bonariensis)

Seasonal variation in gonadal hormones, spatial cognition, and hippocampal attributes: More questions than answers

A large body of research has been dedicated to understanding the factors that modulate spatial cognition and attributes of the hippocampus, a highly plastic brain region that underlies spatial processing abilities. Variation in gonadal hormones impacts spatial memory and hippocampal attributes in vertebrates, although the direction of the effect has not been entirely consistent. To add complexity, individuals in the field must optimize fitness by coordinating activities with the appropriate environmental cues, and many of these behaviors are correlated tightly with seasonal variation in gonadal hormone release. As such, it remains unclear if the relationship among systemic gonadal hormones, spatial cognition, and the hippocampus also exhibits seasonal variation. This review presents an overview of the relationship among gonadal hormones, the hippocampus, and spatial cognition, and how the seasonal release of gonadal hormones correlates with seasonal variation in spatial cognition and hippocampal attributes. Additionally, this review presents other neuroendocrine mechanisms that may be involved in modulating the relationship among seasonality, gonadal hormone release, and the hippocampus and spatial cognition, including seasonal rhythms of steroid hormone binding globulins, neurosteroids, sex steroid hormone receptor expression, and hormone interactions. Here, endocrinology, ecology, and behavioral neuroscience are brought together to present an overview of the research demonstrating the mechanistic effects of systemic gonadal hormones on spatial cognition and the hippocampus, while, at a functional level, superimposing seasonal effects to examine ecologically-relevant circannual changes in gonadal hormones and spatial behaviors.

Serum Sex Hormone Binding Globulin Concentration as a Predictor of Ovarian Response During Controlled Ovarian Hyperstimulation

Purpose: Serum concentrations of sex hormone binding globulin (SHBG), a glycated homodimeric plasma transport protein, correlate positively with the total number of follicles in women with infertility. However, the relationship between serum SHBG concentrations and the ovarian response during controlled ovarian hyperstimulation (COH) and whether this relationship differs between women with and without polycystic ovary syndrome (PCOS) remains unclear.

Methods: The study cohort included 120 participants (60 non-PCOS and 60 PCOS) undergoing in vitro fertilization. Serum samples were collected from each participant every 2–3 days during the COH cycle. The concentrations of serum SHBG and other sex hormones were determined to investigate the relationship between serum SHBG concentrations and the ovarian response in women with and without PCOS.

Results: We found that the serum SHBG concentration was positively correlated with the ovarian response in non-PCOS patients but not in PCOS patients.

Conclusion: The serum SHBG concentration may be clinically useful as a predictor of the ovarian response during COH in patients without PCOS.