To elucidate mechanisms that underlie the profound physiological effects of the monoamine precursors 5-hydroxy-L-tryptophan (5-HTP) and L-3,4-dihydroxyphenylalanine (L-DOPA), we examined their action on single monoaminergic neurons isolated from the ganglia of the gastropod snail Lymnaea stagnalis. In isolated serotonergic PeA motoneurons, 5-HTP produced excitation. The effect was mimicked by serotonin at 0.5-1 microM, masked by pretreatment with serotonin at higher concentrations, and abolished by the inhibitor of aromatic amino acid decarboxylase (AAAD) m-hydroxybenzylhydrazine (NSD-1015), the inhibitor of the vesicular monoamine transporter reserpine or the serotonin receptor antagonist mianserin. Exposure of the dopaminergic interneurons RPeD1 to L-DOPA caused a biphasic effect composed of a depolarization followed by a hyperpolarization. AAAD inactivation with NSD-1015, as well as the blockade of dopamine receptors with sulpiride, resulted in the enhancement of the excitatory effect, and the abolition of the inhibitory effect. Dopamine caused hyperpolarization and masked the inhibitory phase of L-DOPA action. The results show that precursors affect the rate of firing of isolated monoaminergic neurons and that their effect is completely or partially mediated by the enhanced synthesis of the respective neurotransmitter, followed by extrasynaptic release of the latter and activation of extrasynaptic autoreceptors.
Since the discovery of orexin/hypocretin, numerous studies have accumulated evidence demonstrating its key role in various aspects of neuromodulation, including addiction, motivation, and arousal. This paper focuses on the projection of orexin neurons to specific target brain regions through distinct neural pathways to regulate sleep and arousal. We provide a detailed discussion of the projection mechanisms of orexin neurons to downstream neurons, particularly emphasizing their activation of monoaminergic and cholinergic neurons associated with arousal.
Exercise activates the dorsal hippocampus that triggers synaptic and cellar plasticity and ultimately promotes memory formation. For decades, these benefits have been explored using demanding and stress-response-inducing exercise at moderate-to-vigorous intensities. In contrast, our translational research with animals and humans has focused on light-intensity exercise (light exercise) below the lactate threshold (LT), which almost anyone can safely perform with minimal stress.
Department of Rehabilitation, the First Affiliated Hospital, Fujian Medical University, Fuzhou 350005, China; Department of Rehabilitation, National Regional Medical Center, Binhai Campus of the First Affiliated Hospital, Fujian Medical University, Fuzhou 350212, China. Electronic address:
Vagus nerve stimulation (VNS) has garnered significant attention as a promising bioelectronic therapy. In recent years, respiratory-gated auricular vagal afferent nerve stimulation (RAVANS), a novel non-invasive vagus nerve stimulation technique, has emerged. RAVANS integrates respiration with transcutaneous auricular vagus nerve stimulation (taVNS) and shares a similar mechanism of action to traditional VNS.
The study investigates the role of the lateral habenula (LHb) in regulating respiratory responses during psychological stress, focusing on how it affects breathing patterns in rats.
Electrical stimulation of the LHb in anesthetized rats led to increased respiratory frequency and ventilation, indicating its influence on breathing.
The results suggest that dopamine from the ventral tegmental area (VTA) mediates the LHb's effects on respiration, while serotonin negatively regulates this response, highlighting a complex neural circuit involved in stress-related breathing changes.
Mapping neurotransmitter identities to neurons is key to understanding information flow in a nervous system. It also provides valuable entry points for studying the development and plasticity of neuronal identity features. In the nervous system, neurotransmitter identities have been largely assigned by expression pattern analysis of neurotransmitter pathway genes that encode neurotransmitter biosynthetic enzymes or transporters.
