TNFR1-mediated neuroinflammation is necessary for respiratory deficits observed in 6-hydroxydopamine mouse model of Parkinsońs Disease

Banisteriopsis caapi extract: Implications for neuroinflammatory pathways in Locus coeruleus lesion rodent model

ETHNOPHARMACOLOGY RELEVANCE

Ayahuasca is a beverage obtained from the decoctions of Banisteriopsis caapi (Spruce ex Griseb.) Morton and Psychotria viridis Ruiz & Pav., used throughout the Amazon as a medicinal beverage for healing and spiritual exploration. The Banisteriopsis caapi extract consists of harmine, harmaline, and tetrahydroharmine (THH); which inhibit the isoforms of monoamine oxidase A and B. In the central nervous system (CNS), it can increase the norepinephrine (NE) concentration, produced in the Locus coeruleus (LC), reducing inflammation that is associated with some neurological disease, such as Parkinson's disease and Alzheimer's disease.

AIM OF THE STUDY

evaluate the effects of treatment with B. caapi extract on the neuroinflammatory profile in animals with selective LC lesions.

MATERIAL AND METHODS

male Wistar rats with LC lesions induced by 6-hydroxydopamine were treated with B. caapi extract. Subsequently, behavioral tests were conducted, including the elevated plus maze, rotarod, and open field. Tyrosine hydroxylase positive (TH+) neurons and IBA-1 positive microglia were quantified from the LC inflammatory markers and free radical products were assessed.

RESULTS

Both 6-Hydroxydopamine hydrochloride and the Banisteriopsis caapi extract causes reduction of LC neurons, at the concentration and frequency used. The LC depletion and the treatment of B. caapi extract interfere with locomotion. B. caapi extract and the LC lesion increased the number and activation of inflammatory cells, such as microglia. B. caapi extract decreases IL-10 in the hippocampus and BDNF gene expression.

CONCLUSION

This study suggests that B. caapi extract (at the concentration and frequency used) promotes noradrenergic neuron depletion and creates a proinflammatory environment in the CNS.

Sleep-related respiratory disruptions and laterodorsal tegmental nucleus in a mouse model of Parkinson's disease

Parkinson's disease (PD) is a chronic neurodegenerative disorder affecting the motor system, with non-classic symptoms such as sleep disturbances and respiratory dysfunctions. These issues reflect a complex pathophysiological interaction that severely impacts quality of life. Using a 6-hydroxydopamine (6-OHDA) mouse model of PD, we investigated these connections by analyzing sleep patterns and respiratory parameters during non-rapid eye movement (NREM) and rapid eye movement (REM) sleep. Our findings revealed altered breathing, including reduced respiratory frequency and increased apneas during both NREM and REM. To address these abnormalities, we employed chemogenetic stimulation of cholinergic neurons in the laterodorsal tegmental nucleus (LDTg), a key region for sleep-wake regulation and respiratory modulation. This intervention normalized respiratory function. These results highlight the critical role of LDTg cholinergic neurons in the coordinating sleep and breathing, suggesting that targeting these neurons could offer a therapeutic strategy for managing PD-related respiratory complications.

Parkinson's disease models and death signaling: what do we know until now?

Parkinson's disease (PD) is the second neurodegenerative disorder most prevalent in the world, characterized by the loss of dopaminergic neurons in the Substantia Nigra (SN). It is well known for its motor and non-motor symptoms including bradykinesia, resting tremor, psychiatric, cardiorespiratory, and other dysfunctions. Pathological apoptosis contributes to a wide variety of diseases including PD. Various insults and/or cellular phenotypes have been shown to trigger distinct signaling events leading to cell death in neurons affected by PD. The intrinsic or mitochondrial pathway, inflammatory or oxidative stress-induced extrinsic pathways are the main events associated with apoptosis in PD-related neuronal loss. Although SN is the main brain area studied so far, other brain nuclei are also affected by the disease leading to non-classical motor symptoms as well as non-motor symptoms. Among these, the respiratory symptoms are often overlooked, yet they can cause discomfort and may contribute to patients shortened lifespan after disease diagnosis. While animal and in vitro models are frequently used to investigate the mechanisms involved in the pathogenesis of PD in both the SN and other brain regions, these models provide only a limited understanding of the disease's actual progression. This review offers a comprehensive overview of some of the most studied forms of cell death, including recent research on potential treatment targets for these pathways. It highlights key findings and milestones in the field, shedding light on the potential role of understanding cell death in the prevention and treatment of the PD. Therefore, unraveling the connection between these pathways and the notable pathological mechanisms observed during PD progression could enhance our comprehension of the disease's origin and provide valuable insights into potential molecular targets for the developing therapeutic interventions.

Neuroanatomical frameworks for volitional control of breathing and orofacial behaviors

Breathing is the only vital function that can be volitionally controlled. However, a detailed understanding how volitional (cortical) motor commands can transform vital breathing activity into adaptive breathing patterns that accommodate orofacial behaviors such as swallowing, vocalization or sniffing remains to be developed. Recent neuroanatomical tract tracing studies have identified patterns and origins of descending forebrain projections that target brain nuclei involved in laryngeal adductor function which is critically involved in orofacial behavior. These nuclei include the midbrain periaqueductal gray and nuclei of the respiratory rhythm and pattern generating network in the brainstem, specifically including the pontine Kölliker-Fuse nucleus and the pre-Bötzinger complex in the medulla oblongata. This review discusses the functional implications of the forebrain-brainstem anatomical connectivity that could underlie the volitional control and coordination of orofacial behaviors with breathing.