The Utility of Capsicum annuum L. in Internal Medicine and In Dentistry: A Comprehensive Review

Capsaicin is a chili peppers extract, genus Capsicum, commonly used as a food spice. Since ancient times, Capsaicin has been used as a "homeopathic remedy" for treating a wild range of pathological conditions but without any scientific knowledge about its action. Several studies have demonstrated its potentiality in cardiovascular, nephrological, nutritional, and other medical fields. Capsaicin exerts its actions thanks to the bond with transient receptor potential vanilloid subtype 1 (TRPV1). TRPV1 is a nociceptive receptor, and its activation starts with a neurosensitive impulse, responsible for a burning pain sensation. However, constant local application of Capsaicin desensitized neuronal cells and leads to relief from neuropathic pain. In this review, we analyze the potential adjuvant role of Capsaicin in the treatment of different pathological conditions either in internal medicine or dentistry. Moreover, we present our experience in five patients affected by oro-facial pain consequent to post-traumatic trigeminal neuropathy, not responsive to any remedy, and successfully treated with topical application of Capsaicin. The topical application of Capsaicin is safe, effective, and quite tolerated by patients. For these reasons, in addition to the already-proven beneficial actions in the internal field, it represents a promising method for the treatment of neuropathic oral diseases

The role of renal afferent signalling in chronic intermittent hypoxia-induced sympathoexcitation and hypertension

Introduction: Sensory inputs from the kidney induce sympatho-excitation, and are integrated in brainstem regions receiving protective sensory inputs from high- and low-pressure baroreceptors. Blunted baroreflex control of renal sympathetic nerve activity (RSNA) was revealed in hypertension models that involve renal inflammation. Suppression of inflammation restored the normal baroreflex control of RSNA in some of these models, suggesting that renal inflammation impairs baroreflex control of blood pressure through the disruption of renal afferent nerve signalling. Renal oxidative stress and inflammation are evident following exposure to chronic intermittent hypoxia (CIH) in addition to blunted baroreflex control of heart rate. However, little information is available about the baroreflex control of RSNA. In addition, because kidney injury disrupts renal afferent nerve signalling, changes in the renorenal reflex control of sympathetic outflow may occur following exposure to CIH. Therefore, understanding the stage at which baroreflexes and the reno-renal reflex are altered is required to explore the mechanisms that contribute to the early CIH-induced sympathetic hyperactivity and the onset of hypertension. Methods: Following exposure to CIH or normoxia, baroreflexes were examined under anaesthesia. Kidney excretory function was measured during the assessment of low-pressure baroreflex by volume expansion (VE). Baroreflexes were assessed before and after blockade of renal TRPV1 channels. Moreover, to investigate if the excitatory reno-renal reflex contributes to sympathetic over-activity in CIH, renal afferent nerves located in the renal pelvic wall were chemically stimulated by bradykinin and capsaicin, or inhibited by bradykinin receptor type 1 (BK1R) and/or 2 (BK2R) blockers, and cardiovascular and RSNA responses were measured. Renal histology, inflammation and oxidative stress biomarkers were assessed. Results: CIH-exposed rats were hypertensive with elevated RSNA, with no evidence of glomerular hypertrophy or renal inflammation and oxidative stress. Water and sodium excretion were increased following CIH exposure. However, diuresis and natriuresis during VE were attenuated in CIH-exposed rats despite preservation of the progressive decrease in RSNA during VE, suggesting that altered kidney excretory function in CIH was independent of neural control. The increase in atrial natriuretic peptide during VE was attenuated in CIH. Assessment of the high-pressure baroreflex revealed decreased slope in CIH-exposed rats with substantial hypertension, but not when hypertension was modest. Diuresis and natriuresis during VE were enhanced in CIH-exposed and sham rats following the intra-renal blockade of TPRV1 channels, suggesting a role for renal TRPV1 in the control of renal excretory function. However, TRPV1 protein expression in the kidney was unchanged and TRPV1 activation by intra-renal pelvic infusion of capsaicin induced a similar sympatho-excitation in sham and CIH-exposed rats. Moreover, sympatho-excitation during intra-renal pelvic infusion of bradykinin was suppressed in CIH-exposed rats. This was associated with 53% decreased expression of BK2R in the renal pelvic wall of CIH-exposed rats compared with sham rats. Inhibition of renal bradykinin receptors did not affect cardiovascular parameters or RSNA in sham and CIH-exposed rats. Conclusion: Our findings show no evidence of an excitatory reno-renal reflex driving sympathetic hyperactivity and the onset of hypertension in CIH. This was revealed by the absence of renal pathology despite the presence of a hypertensive phenotype. Moreover, the findings indicate suppressed rather than exacerbated sympatho-excitation in CIH-exposed rats in response to bradykinin. In addition, the baroreflex control of RSNA was maintained in CIHexposed rats with modest hypertension, indicating that blunted baroreflex control is not obligatory for the onset of hypertension in CIH. Overall, renal injury appears to develop after the progressive elevation of blood pressure, although it may also develop in circumstances of exposure to severe CIH, suggesting that chronic kidney disease, frequently observed concomitant with obstructive sleep apnoea (OSA), may be mitigated if OSA is controlled at an early stage

Salt Taste, Nutrition, and Health

Salt (NaCl) is a key component of the human diet because it provides the sodium ion (Na+), an essential mineral for our body. Na+ regulates extracellular fluid volume and plays a key role in many physiological processes, such as the generation of nerve impulses. Na+ is lost continuously through the kidneys, intestine, and sweating. Thus, to maintain proper bodily balance, losses have to be balanced with foods containing this cation. The need for salt explains our ability to detect Na+ in foodstuffs: Na+ elicits a specific taste sensation called “salty”, and gustatory sensitivity to this cation is crucial for regulating its intake. Indeed, the widespread use of salt in food products for flavoring and to improve their palatability exploits our sense of taste for Na+. When consumed in excess, however, salt might be detrimental to health because it may determine an increase in blood pressure—a major risk factor for many cardiovascular diseases. Understanding how salt taste works and how it affects food preference and consumption is therefore of paramount importance for improving human nutrition. This book comprises cutting-edge research dealing with salt taste mechanisms relevant for nutrition and health

A review of the effects of Capsicum annuum L. and its constituent, capsaicin, in metabolic syndrome

Objective(s): Metabolic syndrome, a coexisting of high blood glucose, obesity, dyslipidemia and hypertension, is an important risk factor for cardiovascular disease occurrence and mortality. Recently, there is a rising demand for herbal drugs which have less adverse effects and have shown more beneficial effects in comparison with synthetic options. Red pepper, with the scientific name of Capsicum annuum, belongs to the Solanaceae family. The lipid-lowering, antihypertensive, antidiabetic and anti-obesity effects of C. annuum have been demonstrated in several studies. Materials and Methods:  In this review, we summarized different animal and human studies on the effect of red pepper and capsaicin on different components of metabolic syndrome which are risk factors for cardiovascular diseases (CVDs). Results: According to these studies, red pepper as well as capsaicin has ability to control of metabolic syndrome and its related disorders such as obesity, disrupted lipid profile, diabetes and its complications.Conclusion: Red pepper has beneficial effects on metabolic syndrome and can decrease the risk of mortality due to cardiovascular diseases, but still more research projects need to be done and confirm its advantageous especially in humans

CENTRAL NEURAL MECHANISMS OF SALT-SENSITIVE HYPERTENSION

Hypertension (HTN) is a major risk factor for the development of cardiovascular disease, and it’s estimated that over 80 million adults in the United States have HTN. Essential HTN often demonstrates sensitivity to salt, and reductions in dietary salt attenuate high blood pressure in this population. Evidence indicates that the paraventricular nucleus (PVN) of the hypothalamus is a key driver of HTN due to excess salt intake. The cellular mechanisms whereby PVN neuronal activity is augmented in response to salt are largely unknown. Previous work from our lab has demonstrated that small conductance calcium activated potassium (SK) channel function is diminished in the PVN in HTN induced by a 2% high salt (HS) combined with chronic infusion of angiotensin II (AngII) (AngII-salt HTN). In study 1 we demonstrate SK channel dysfunction in AngII-salt HTN. Furthermore, SK channel dysfunction was present in rats fed a HS diet alone indicating that dietary salt likely plays a dominant role in reducing SK channel function. In study 2 we examined the contribution of the endoplasmic reticulum (ER), and intracellular organ largely responsible for intracellular Ca2+ homeostasis, in regulating sympathoexcitatory response in vivo, and neuronal excitability in vitro. We demonstrate that inhibiting ER function in the PVN augments sympathetic nerve activity and blood pressure in vivo, and neuronal excitability in vitro. We further demonstrate that HS diet augments excitability of PVN neurons through altered ER Ca2+ store function. Collectively, we demonstrate that HS diet diminishes SK channel function in the PVN and altered ER Ca2+ regulation may contribute to the augmented neuronal excitability in the PVN due to HS intake. Together, these mechanisms providing new and exciting targets for the treatment of salt-sensitive HTN

The new technique for accurate estimation of the spinal cord circuitry:recording reflex responses of large motor unit populations

We propose and validate a non-invasive method that enables accurate detection of the discharge times of a relatively large number of motor units during excitatory and inhibitory reflex stimulations. HDsEMG and intramuscular EMG (iEMG) were recorded from the tibialis anterior muscle during ankle dorsiflexions performed at 5%, 10%, and 20% of the maximum voluntary contraction (MVC) force, in 9 healthy subjects. The tibial nerve (inhibitory reflex) and the peroneal nerve (excitatory reflex) were stimulated with constant current stimuli. In total, 416 motor units were identified from the automatic decomposition of the HDsEMG. The iEMG was decomposed using a state-of-the-art decomposition tool and provided 84 motor units (average of two recording sites). The reflex responses of the detected motor units were analyzed using the peri-stimulus time histogram (PSTH) and the peri-stimulus frequencygram (PSF). The reflex responses of the common motor units identified concurrently from the HDsEMG and the iEMG signals showed an average disagreement (the difference between number of observed spikes in each bin relative to the mean) of 8.2±2.2% (5% MVC), 6.8±1.0% (10% MVC), and 7.5±2.2% (20% MVC), for reflex inhibition, and 6.5±4.1%, 12.0±1.8%, 13.9±2.4%, for reflex excitation. There was no significant difference between the characteristics of the reflex responses, such as latency, amplitude and duration, for the motor units identified by both techniques. Finally, reflex responses could be identified at higher force (four of the nine subjects performed contraction up to 50% MVC) using HDsEMG but not iEMG, because of the difficulty in decomposing the iEMG at high forces. In conclusion, single motor unit reflex responses can be estimated accurately and non-invasively in relatively large populations of motor units using HDsEMG. This non-invasive approach may enable a more thorough investigation of the synaptic input distribution on active motor units at various force levels