Alteration of Testosterone Levels Changes Brain Wave Activity Patterns and Induces Aggressive Behavior in Rats

Abstract

Testosterone is responsible for several changes in the brain, including behavioral and emotional responses, memory, and cognition. Given this, we investigated changes in the brain wave profile caused by supplementation with exogenous testosterone in both castrated and non-castrated rats. We also investigated the serum testosterone levels, renal and hepatic function, and the lipid and behavioral profiles. We found changes in the spectral wave power in both groups (castrated and non-castrated animals) supplemented with exogenous testosterone, consistent with an aggressive/hostile profile. These changes were observed in the electrocorticographic evaluation associated with increased power in low-frequency (delta and theta) and high-frequency (beta and gamma) activity in the supplemented animals. The castrated animals presented a significant decrease of wave power in the alpha frequency. This correlated with a decrease of the performance of the animals in the elevated plus-maze evaluation, given that the alpha wave is linked to the execution and visualization of motor processes. In the behavioral evaluation, the castrated animals presented a reduced permanence time in the elevated-plus maze, although this was prevented by the supplementation of testosterone. Testosterone supplementation induced aggressive behavior in non-castrated animals, but not in castrated ones. Supplemented animals had significantly elevated serum testosterone levels, while their urea levels were significantly lower, but without clinical significance. Our data indicate that testosterone supplementation in non-castrated rats, but not in castrated ones, causes electrocorticographic changes that could be associated with more aggressive and hostile behavior, in addition to indicating a potential for personality disorder. However, further studies are required to elucidate the cellular and molecular changes caused by acute testosterone supplementation.

Increased Relative Delta Bandpower and Delta Indices Revealed by Continuous qEEG Monitoring in a Rat Model of Ischemia-Reperfusion

“…The EEGs were recorded as described by Estumano et al ( 22 ) and Ferreira et al ( 23 ). Briefly, the animals were anesthetized with ketamine (80 mg/kg, i.p.)…”

Electrocorticographic description of the effects of anticonvulsant drugs used to treat lidocaine‐induced seizures

“…The ECoG recordings were obtained using the procedures described by Estumano et al. (2019). For this, the animals were anesthetized with ketamine hydrochloride (80 mg/kg, i.p.)…”

Electrocorticographic patterns dominated by low-frequency waves in camphor-induced seizures

“…Electrocorticographic recordings and data analyses. The ECoG recordings and offline data analyses followed the procedures described by Estumano et al 31 . The animals were first anesthetized with ketamine hydrochloride (80 mg/kg, i.p.)…”

“…Five days after surgery, the ECoGs were obtained using a digital data acquisition system and the offline analyses were conducted. The analyses were run at a frequency of up to 50 Hz, and split into bands as in Estumano et al 31 , that is, delta (1-4 Hz), theta (4-8 Hz), alpha (8-12 Hz), beta (12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28), and gamma (28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40), for interpretation of the wave dynamics during the development of the seizure. The recordings followed a predefined protocol: the animals were immobilized carefully for 10 min for habituation, to avoid interference in the records.…”