Biology subjects

Alves, N. D.

Publications and source records attributed to Alves, N. D..

3 recordsLinked to original sources

bioRxiv2024

Preemptive minocycline decreases allodynia and depressive-like behaviors in a peripheral neuropathy rat model: a preliminary study

Background and ObjectiveThe neuroimmune system plays a critical role at all phases of chronic pain including at its onset. We therefore hypothesized that preemptive immunomodulation could decrease susceptibility and/or offer protection to pain. Materials and MethodsSix days before the spared nerve injury (SNI), Wistar Han rats were treated with either the immunomodulator minocycline (MIN) or vehicle (VEH). After that, half of the animals from each group switch treatments for additional 7 days, resulting in 4 groups: continuous treatment (MIN/MIN), pretreatment (MIN/VEH), early treatment (VEH/MIN) and the control (VEH/VEH). Mechanical allodynia was recorded using Von Frey test until 4 weeks after SNI where depressive-like behaviors of the animals were also assessed using sucrose preference test. ResultsThe continuous treatment provided sustained protection against mechanical allodynia, with rats in this group showing a significantly higher threshold to pain sensitivity compared to those in VEH/VEH. In contrast, pain relief effects were not observed with MIN/VEH and VEH/MIN. Additionally, animals in MIN/MIN, and VEH/MIN exhibited decreased anhedonic-like behavior at 30 days after SNI, relative to the control. ConclusionsThe exposure to an anti-inflammatory drug circa the installation of a neuropathic lesion had a positive impact on allodynia and on anhedonic behavior for a relatively long period after treatment cessation. The results support the assertions that pain trajectories can be altered at pain early stages by targeting the neuroimmune system. This proof-of-concept has the potential to be broadened to other drugs and/or therapeutical schemes. HighlightsChronic pain susceptibility varies across individuals. (endo)phenotypes of susceptibility manifest prior/circa pain onset. Preemptive minocycline treatment transiently decreases allodynia. Preemptive minocycline treatment provides sustained reduction of depressive-like behavior. Immune system modulation prior to pain onset or at early stages have beneficial outcomes.

neuroscience↗

bioRxiv2023

Medial Prefrontal Cortex Serotonin Input Regulates Cognitive Flexibility in Mice

The medial prefrontal cortex (mPFC) regulates cognitive flexibility and emotional behavior. Neurons that release serotonin project to the mPFC, and serotonergic drugs influence emotion and cognition. Yet, the specific roles of endogenous serotonin release in the mPFC on neurophysiology and behavior are unknown. We show that axonal serotonin release in the mPFC directly inhibits the major mPFC output neurons. In serotonergic neurons projecting from the dorsal raphe to the mPFC, we find endogenous activity signatures pre-reward retrieval and at reward retrieval during a cognitive flexibility task. In vivo optogenetic activation of this pathway during pre-reward retrieval selectively improved extradimensional rule shift performance while inhibition impaired it, demonstrating sufficiency and necessity for mPFC serotonin release in cognitive flexibility. Locomotor activity and anxiety-like behavior were not affected by either optogenetic manipulation. Collectively, our data reveal a powerful and specific modulatory role of endogenous serotonin release from dorsal raphe-to-mPFC projecting neurons in cognitive flexibility.

neuroscience↗

bioRxiv2021

Constitutive AP2gamma deficiency reduces postnatal hippocampal neurogenesis and induces behavioral deficits in juvenile mice that persist during adulthood

The transcription factor activating protein two gamma (AP2{gamma}) is an important regulator of neurogenesis both during embryonic development as well as in the postnatal brain, but its role for neurophysiology and behavior at distinct postnatal periods is still unclear. In this work, we explored the neurogenic, behavioral, and functional impact of a constitutive AP2{gamma} heterozygous deletion in mice from early postnatal development until adulthood. Constitutive AP2{gamma} heterozygous deletion in mice caused a reduction of hippocampal transient amplifying progenitors (TAPs) in the postnatal brain, inducing significant impairments on hippocampal-dependent emotional- and cognitive-behavioral tasks including anxiety-like behavior and cognitive deficits, typically associated with an intact neurogenic activity. Moreover, AP2{gamma} deficiency impairs dorsal hippocampus-to-prefrontal cortex functional connectivity. We observed a progressive and cumulative impact of constitutive AP2{gamma} deficiency on the hippocampal glutamatergic neurogenic process, as well as alterations on limbic-cortical connectivity, together with impairments on emotional and cognitive behaviors from juvenile to adult periods. Collectively, the results herein presented demonstrate the importance of AP2{gamma} in the generation of glutamatergic neurons in the postnatal brain and its impact on behavioral performance.

neuroscience↗