Testosterone regulates the emission of ultrasonic vocalizations and mounting behavior during different developmental periods in mice

Rodent ultrasonic vocal interaction resolved with millimeter precision using hybrid beamforming

Ultrasonic vocalizations (USVs) fulfill an important role in communication and navigation in many species. Because of their social and affective significance, rodent USVs are increasingly used as a behavioral measure in neurodevelopmental and neurolinguistic research. Reliably attributing USVs to their emitter during close interactions has emerged as a difficult, key challenge. If addressed, all subsequent analyses gain substantial confidence. We present a hybrid ultrasonic tracking system, Hybrid Vocalization Localizer (HyVL), that synergistically integrates a high-resolution acoustic camera with high-quality ultrasonic microphones. HyVL is the first to achieve millimeter precision (~3.4-4.8 mm, 91% assigned) in localizing USVs, ~3× better than other systems, approaching the physical limits (mouse snout ~10 mm). We analyze mouse courtship interactions and demonstrate that males and females vocalize in starkly different relative spatial positions, and that the fraction of female vocalizations has likely been overestimated previously due to imprecise localization. Further, we find that when two male mice interact with one female, one of the males takes a dominant role in the interaction both in terms of the vocalization rate and the location relative to the female. HyVL substantially improves the precision with which social communication between rodents can be studied. It is also affordable, open-source, easy to set up, can be integrated with existing setups, and reduces the required number of experiments and animals.

Cadmium induces testosterone synthesis disorder by testicular cell damage via TLR4/MAPK/NF-κB signaling pathway leading to reduced sexual behavior in piglets

Cadmium (Cd) is a highly toxic metal pollutant that can endanger the life and health of animals. Toll-like receptor 4 (TLR4) can result in testicular cell damage by positively regulating mitogen-activated protein kinase (MAPK)/nuclear factor-kappaB (NF-κB) signaling pathway. Meanwhile, Testosterone (T) synthesis disorder can affect sexual behavior. However, the harmful influence of Cd on animal sexual behavior during its growth and development and the role of TLR4/MAPK/NF-κB signaling pathway in testicular cell damage and testosterone production remained poorly understood. Forty-two-day-old male piglets were fed with diets that contained CdCl₂ (20 mg Cd/kg) for 40 days to explore the toxic effects of Cd on sexual behavior. The results showed that Cd activated TLR4, promoted MAPK (p-ERK, p-JNK, and p-p38)/NF-κB expression, induced apoptosis (Caspase-3, Cleaved Caspase3, Bax, Cyt-c, and Caspase-9 expression increased, but Bcl-2 expression decreased) and necroptosis (MLKL, RIPK1, and RIPK3 expression increased) in piglet testis. In addition, Cd exposure decreased mRNA expression of STAR, CYP11A1, 3β-HSD, CYP17A1, and 17β-HSD of testis and the concentrations of T and thyroid-stimulating hormone (TSH). Both the mRNA and protein expression levels of the major genes in TLR4/MAPK/NF-κB signaling pathway, apoptosis signaling pathway, and necroptosis signaling pathway increased significantly and the expression levels of testosterone decreased gradually in pig Leydig cells cultured in vitro after being treated with different concentrations of Cd. Moreover, Cd reduced sexual behavior (the parameters of sniffing, chin resting, and mounting decreased) in piglets. In conclusion, Cd induced testicular cell damage via TLR4/MAPK/NF-κB signaling pathway leading to testosterone synthesis disorder and sexual behavior reduction in piglets.

Unexpected Interacting Effects of Physical (Radiation) and Chemical (Bisphenol A) Treatments on Male Reproductive Functions in Mice

For decades, numerous chemical pollutants have been described to interfere with endogenous hormone metabolism/signaling altering reproductive functions. Among these endocrine disrupting substances, Bisphenol A (BPA), a widely used compound, is known to negatively impact germ and somatic cells in the testis. Physical agents, such as ionizing radiation, were also described to perturb spermatogenesis. Despite the fact that we are constantly exposed to numerous environmental chemical and physical compounds, very few studies explore the impact of combined exposure to chemical and physical pollutants on reproductive health. The aim of this study was to describe the impact of fetal co-exposure to BPA and IR on testicular function in mice. We exposed pregnant mice to 10 µM BPA (corresponding to 0.5 mg/kg/day) in drinking water from 10.5 dpc until birth, and we irradiated mice with 0.2 Gy (γ-ray, RAD) at 12.5 days post-conception. Co-exposure to BPA and γ-ray induces DNA damage in fetal germ cells in an additive manner, leading to a long-lasting decrease in germ cell abundance. We also observed significant alteration of adult steroidogenesis by RAD exposure independently of the BPA exposure. This is illustrated by the downregulation of steroidogenic genes and the decrease of the number of adult Leydig cells. As a consequence, courtship behavior is modified, and male ultrasonic vocalizations associated with courtship decreased. In conclusion, this study provides evidence for the importance of broadening the concept of endocrine disruptors to include physical agents, leading to a reevaluation of risk management and regulatory decisions.

Testosterone Increases the Emission of Ultrasonic Vocalizations With Different Acoustic Characteristics in Mice

Testosterone masculinizes male sexual behavior through an organizational and activational effects. We previously reported that the emission of ultrasonic vocalizations (USVs) in male mice was dependent on the organizational effects of testosterone; females treated with testosterone in the perinatal and peripubertal periods, but not in adults, had increased USV emissions compared to males. Recently, it was revealed that male USVs have various acoustic characteristics and these variations were related to behavioral interactions with other mice. In this regard, the detailed acoustic characteristic changes induced by testosterone have not been fully elucidated. Here, we revealed that testosterone administered to female and male mice modulated the acoustic characteristics of USVs. There was no clear difference in acoustic characteristics between males and females. Call frequencies were higher in testosterone propionate (TP)-treated males and females compared to control males and females. When the calls were classified into nine types, there was also no distinctive difference between males and females, but TP increased the number of calls with a high frequency, and decreased the number of calls with a low frequency and short duration. The transition analysis by call type revealed that even though there was no statistically significant difference, TP-treated males and females had a similar pattern of transition to control males and females, respectively. Collectively, these results suggest that testosterone treatment can enhance the emission of USVs both in male and female, but the acoustic characteristics of TP-treated females were not the same as those of intact males.