Application of neurotransmitters and dental stem cells for pulp regeneration: A review.

Introduction: Although there have been many studies on stem cells, few have investigated how neurotransmitters and stem cell proliferation interact to regenerate dental pulp. Dental pulp regeneration is an innovative procedure for reviving dental pulp, if feasible for the entire tooth. Upon tooth injury, activated platelets release serotonin and dopamine in bulk to mobilize dental pulp stem cells to mediate natural dental repair. This has induced research on the role of neurotransmitters in increasing the proliferation rate of stem cells. This review also covers prospective future treatments for dental pulp regeneration. Methods: A literature search was performed via PubMed and ScienceDirect from 2001 to 2022, using the keywords "neurotransmitter," "stem cell," "tooth regeneration," "tooth repair," "regenerative dentistry," and "dental pulp." Different inclusion/exclusion criteria were used, and the search was restricted to English articles. Results: Nine publications reporting neurotransmitter interactions with stem cells for tooth and pulp regeneration were selected. Conclusion: Neurotransmitters were found to interact with dental stem cells. Evidence pointing to neurotransmitters as a factor in the increased proliferation of stem cells was found. This review thus gives hope for tooth pulp regeneration and repair.

Dorsal root ganglia control nociceptive input to the central nervous system.

Accumulating observations suggest that peripheral somatosensory ganglia may regulate nociceptive transmission, yet direct evidence is sparse. Here, in experiments on rats and mice, we show that the peripheral afferent nociceptive information undergoes dynamic filtering within the dorsal root ganglion (DRG) and suggest that this filtering occurs at the axonal bifurcations (t-junctions). Using synchronous in vivo electrophysiological recordings from the peripheral and central processes of sensory neurons (in the spinal nerve and dorsal root), ganglionic transplantation of GABAergic progenitor cells, and optogenetics, we demonstrate existence of tonic and dynamic filtering of action potentials traveling through the DRG. Filtering induced by focal application of GABA or optogenetic GABA release from the DRG-transplanted GABAergic progenitor cells was specific to nociceptive fibers. Light-sheet imaging and computer modeling demonstrated that, compared to other somatosensory fiber types, nociceptors have shorter stem axons, making somatic control over t-junctional filtering more efficient. Optogenetically induced GABA release within DRG from the transplanted GABAergic cells enhanced filtering and alleviated hypersensitivity to noxious stimulation produced by chronic inflammation and neuropathic injury in vivo. These findings support "gating" of pain information by DRGs and suggest new therapeutic approaches for pain relief.

Successful management of dentin hypersensitivity: A narrative review.

The prevalence of dentin hypersensitivity (DH) is increasing around the world. At least one in 10 individuals in the general population has been diagnosed with DH. It is a diagnosis that has significant negative effects on a person's oral health-related quality of life. This condition, which is characterized by sharp, short tooth pain in response to thermal, chemical, tactile, and evaporative stimuli, is more commonly seen in adults. DH has a tremendous impact on the social and financial aspects of patients and society at large. It is essential to recognize the factors that can contribute to a successful treatment outcome to guarantee the overall well-being of DH patients. The aim of this narrative review was to highlight strategies that can lead to successful DH treatment outcomes, along with current updates on DH mechanisms, treatment options, and the latest management approaches. A positive treatment outcome for DH requires a concerted effort from both the patient and the dental practitioner. Highly motivated patients and dental practitioners with sound knowledge of DH diagnosis and available treatment options will ensure successful long-term improvement of DH symptoms.

Immunohistochemistry as a detection tool for ion channels involved in dental pain signaling.

Background: Despite advances in pain detection, diagnosis, and management, the prevalence of dental pain is still on the rise. Although dental pain is not directly related to fatal outcomes, the two most common types of dental pain-dental caries and dentin hypersensitivity-have a significant impact on an individual's quality of life. Understanding the mechanism of the pain pathway is one of the crucial steps in providing better treatment for these patients. Ion channels are critical biomolecules that have been the subject of dental study owing to their roles in the transmission and transduction of external stimuli, as well as in the control and perception of pain. Numerous immunohistochemical (IHC) staining approaches have also been used to identify the many ion channels implicated in peripheral pain signaling in dental pulp. Highlight: This review highlights the critical steps in IHC and its role in the detection of ion channels involved in the dental pain signaling pathway. Conclusion: The key ion channels identified using IHC and whose functions have been widely researched in dental tissues are addressed in this review article.

GABAergic signalling in modulation of dental pain.

Dental pain is a common complaint in patients undergoing endodontic treatment. Despite continuous efforts to develop new pain management strategies and improved treatment approaches, dental pain management remains a continuous challenge to clinicians. Understanding pain signalling mechanisms in the dental pulp along with the molecular targets involved in the dental pain pathway will provide a better view of how dental pain can be managed. The role of γ-Aminobutyric acid (GABA) in pain transduction has been well explored in various literature over the years. GABA and its receptors have been found in parts of the spinal cord and brain that are related to pain perception, thus providing compelling evidence of its role in mediating pain signalling. Based on this evidence, several studies have investigated the expression of GABA and its receptors in the dental pulp as well as its role in dental pain transmission. This review discusses GABA and its receptors in pain signalling, with emphasis on the research progress related to GABAergic signalling in the dental pain pathway.

Local GABAergic signaling within sensory ganglia controls peripheral nociceptive transmission.

The integration of somatosensory information is generally assumed to be a function of the central nervous system (CNS). Here we describe fully functional GABAergic communication within rodent peripheral sensory ganglia and show that it can modulate transmission of pain-related signals from the peripheral sensory nerves to the CNS. We found that sensory neurons express major proteins necessary for GABA synthesis and release and that sensory neurons released GABA in response to depolarization. In vivo focal infusion of GABA or GABA reuptake inhibitor to sensory ganglia dramatically reduced acute peripherally induced nociception and alleviated neuropathic and inflammatory pain. In addition, focal application of GABA receptor antagonists to sensory ganglia triggered or exacerbated peripherally induced nociception. We also demonstrated that chemogenetic or optogenetic depolarization of GABAergic dorsal root ganglion neurons in vivo reduced acute and chronic peripherally induced nociception. Mechanistically, GABA depolarized the majority of sensory neuron somata, yet produced a net inhibitory effect on the nociceptive transmission due to the filtering effect at nociceptive fiber T-junctions. Our findings indicate that peripheral somatosensory ganglia represent a hitherto underappreciated site of somatosensory signal integration and offer a potential target for therapeutic intervention.

Bone Micro-CT Assessments in an Orchidectomised Rat Model Supplemented with Eurycoma longifolia.

Recent studies suggested that Eurycoma longifolia, a herbal plant, may have the potential to treat osteoporosis in elderly male. This study aimed to determine the effects of Eurycoma longifolia supplementation on the trabecular bone microarchitecture of orchidectomised rats (androgen-deficient osteoporosis model). Forty-eight-aged (10-12 months old) Sprague Dawley rats were divided into six groups of sham-operated (SHAM), orchidectomised control (ORX), orchidectomised + 7 mg/rat testosterone enanthate (TEN) and orchidectomised + Eurycoma longifolia 30 mg/kg (EL30), orchidectomised + Eurycoma longifolia 60 mg/kg (EL60), orchidectomised + Eurycoma longifolia 90 mg/kg (EL90). Rats were euthanized following six weeks of treatment. The left femora were used to measure the trabecular bone microarchitecture using micro-CT. Orchidectomy significantly decreased connectivity density, trabecular bone volume, and trabecular number compared to the SHAM group. Testosterone replacement reversed all the orchidectomy-induced changes in the micro-CT parameters. EL at 30 and 60 mg/kg rat worsened the trabecular bone connectivity density and trabecular separation parameters of orchidectomised rats. EL at 90 mg/kg rat preserved the bone volume. High dose of EL (90 mg/kg) may have potential in preserving the bone microarchitecture of orchidectomised rats, but lower doses may further worsen the osteoporotic changes.

Water balance: case study of a constructed wetland as part of the bio-ecological drainage system (BIOECODS).

The Bio-ecological Drainage System, or BIOECODS, is an urban drainage system located at the Engineering Campus, Universiti Sains Malaysia. It consists of a constructed wetland as a part of the urban drainage system to carry storm water in a closed system. In this closed system, the constructed wetland was designed particularly for further treatment of storm water. For the purpose of studying the water balance of the constructed wetland, data collection was carried out for two years (2007 and 2009). The results show that the constructed wetland has a consistent volume of water storage compared to the outflow for both years with correlation coefficients (R(2)) of 0.99 in 2007 and 0.86 in 2009.