Effects of different musical frequencies on NPY and Ghrelin secretion in the rat hypothalamus

Maternal music exposure during pregnancy influences reflexive motor behaviors in mice offspring

Evidence supports that music can modulate many physiological roles, exerting clear effects on the central nervous system. For this effect to be positive, music should be tuned at a frequency of 432 Hz. This study aims to determine the effects of prenatal exposure to music on reflexive motor behaviors in mice offspring. Six pregnant female NMRI mice (8-10 weeks old) were randomly and equally allocated into two groups. Group 1 as control was placed in a normal housing area (average room noise 35 dB), and Group 2 was exposed to music pitched at 432 Hz for 2 h a day played at constant volume (75/80 dB) during pregnancy. Following delivery, four pups from each pregnant mouse were selected, and reflexive motor behaviors including ambulation, hind-limb foot angle, surface righting, grip strength, front- and hind-limb suspension, and negative geotaxis were determined. Based on the findings, prenatal exposure to music significantly increased ambulation score, grip strength, and front- and hind-limb suspension compared to the control group (P < 0.05). Also, prenatal exposure to music significantly decreased hind-limb foot angle, negative geotaxis, and surface righting compared to the control group (P < 0.05). These results suggested that music exposure during pregnancy had a significant positive effect on all tested reflexive motor behaviors in mice offspring.

Selected Acoustic Frequencies Have a Positive Impact on Behavioural and Physiological Welfare Indicators in Thoroughbred Racehorses

(1) Background: Since antiquity, it is considered that sounds influence human emotional states and health. Acoustic enrichment has also been proposed for domestic animals. However, in both humans and animals, effects vary according to the type of sound. Human studies suggest that frequencies, more than melodies, play a key role. Low and high frequencies, music tuning frequency and even EEG slow waves used for 'neurofeedback' produce effects. (2) Methods: We tested the possible impact of such pure frequencies on racehorses' behavior and physiology. A commercial non-audible acoustic stimulus, composed of an array of the above-mentioned frequencies, was broadcasted twice daily and for three weeks to 12 thoroughbred horses in their home stall. (3) Results: The results show a decrease in stereotypic behaviors and other indicators such as yawning or vacuum chewing, an increase in the time spent in recumbent resting and foraging, and better hematological measures during and after the playback phase for 4 of the 10 physiological parameters measured. (4) Conclusions: These results open new lines of research on possible ways of alleviating the stress related to housing and training conditions in racehorses and of improving physical recovery.

Pilot Aquaphotomic Study of the Effects of Audible Sound on Water Molecular Structure

Sound affects the medium it propagates through and studies on biological systems have shown various properties arising from this phenomenon. As a compressible media and a “collective mirror”, water is influenced by all internal and external influences, changing its molecular structure accordingly. The water molecular structure and its changes can be observed as a whole by measuring its electromagnetic (EMG) spectrum. Using near-infrared spectroscopy and aquaphotomics, this pilot study aimed to better describe and understand the sound-water interaction. Results on purified and mineral waters reported similar effects from the applied 432 Hz and 440 Hz frequency sound, where significant reduction in spectral variations and increased stability in water were shown after the sound perturbation. In general, the sound rearranged the initial water molecular conformations, changing the samples’ properties by increasing strongly bound, ice-like water and decreasing small water clusters and solvation shells. Even though there was only 8 Hz difference in applied sound frequencies, the change of absorbance at water absorbance bands was specific for each frequency and also water-type-dependent. This also means that sound could be effectively used as a perturbation tool together with spectroscopy to identify the type of bio, or aqueous, samples being tested, as well as to identify and even change water functionality.

Food-seeking behavior is triggered by skin ultraviolet exposure in males

Sexual dimorphisms are responsible for profound metabolic differences in health and behavior. Whether males and females react differently to environmental cues, such as solar ultraviolet (UV) exposure, is unknown. Here we show that solar exposure induces food-seeking behavior, food intake, and food-seeking behavior and food intake in men, but not in women, through epidemiological evidence of approximately 3,000 individuals throughout the year. In mice, UVB exposure leads to increased food-seeking behavior, food intake and weight gain, with a sexual dimorphism towards males. In both mice and human males, increased appetite is correlated with elevated levels of circulating ghrelin. Specifically, UVB irradiation leads to p53 transcriptional activation of ghrelin in skin adipocytes, while a conditional p53-knockout in mice abolishes UVB-induced ghrelin expression and food-seeking behavior. In females, estrogen interferes with the p53-chromatin interaction on the ghrelin promoter, thus blocking ghrelin and food-seeking behavior in response to UVB exposure. These results identify the skin as a major mediator of energy homeostasis and may lead to therapeutic opportunities for sex-based treatments of endocrine-related diseases.

Restraint stress potentiates neuropeptide Y-mediated impairment on spatial memory in rats

Memory is the ability to store, retrieve and use information that requires a progressive time-dependent stabilization process known as consolidation to be established. The hippocampus is essential for processing all the information that forms memory, especially spatial memory. Neuropeptide Y (NPY) affects memory, so in this study we investigated the participation and recruitment of NPY receptors during spatial memory consolidation in rats. Using the water maze test, we show that NPY (1 pmol) injected into the dorsal hippocampus impaired memory consolidation and that previous restraint stress (30 min) potentiates NPY effects, i.e. further impaired memory consolidation. Using selective antagonists for NPY Y₁ and Y₂ receptors we demonstrate that both receptors play a key role on spatial memory consolidation. Our data suggest that NPY modulates aversive and adaptive memory formation by NPY receptors activation.

Prenatal music exposure influences weight, ghrelin expression, and morphology of rat hypothalamic neuron cultures

Music plays an important role in brain physiology, in some areas related to emotions, food intake and body weight, such as the hypothalamus. There are different frequencies to which it can be tuned, today the most utilized is at 440 Hz, while in the past the 432 Hz frequency was more used to show particular effects on brain. It is known that Ghrelin, a peptide hormone, regulates food intake in the hypothalamus; in a previous paper, we reported that musical stimuli at 432 Hz modified the Ghrelin expression in the rat, increasing beneficial effects on metabolism. In this study, we used this frequency and we focused our attention on body weight, Ghrelin expression, and neuron morphology in hypothalamic cultures. To investigate the role of music, we utilized newborn pups from pregnant rats that were exposed to music stimuli at 432 Hz during the perinatal period and for the postnatal period, some for 3 days (P3) and others for 6 days (P6). Some pups were not exposed to music stimuli (controls). Our results showed that music increased the body weight of pups; in addition, enhanced Ghrelin expression in hypothalamic neurons and their axonal elongation were highlighted by immunocytochemical techniques. Moreover, we found that the positive music effect started in pups at P3 and increased at P6 compared with controls. These results suggest that the musical frequency at 432 Hz could stimulate the orexigenic Ghrelin effects influencing the increase in body weight and affecting the number of hypothalamic neurons expressing Ghrelin.

Effect of music at 432 Hz and 440 Hz on dental anxiety and salivary cortisol levels in patients undergoing tooth extraction: a randomized clinical trial

Objective

The aim of this study was to compare the effects of music at 432 Hz, 440 Hz, and no music on the clinical perception of anxiety and salivary cortisol levels in patients undergoing tooth extraction.

Methodology

A parallel-group randomized clinical trial was conducted. Forty-two patients (average age: 23.8±7.8 years, 27 women) with a moderate level of anxiety were distributed in three groups: use of music for 15 minutes at a frequency of 432 Hz (n=15), at 440 Hz (n=15) and a control group without music (n=12). The CORAH Dental Anxiety Scale and salivary cortisol levels, estimated by the solid phase enzyme-linked immunosorbent assay (ELISA), were measured and compared before and after the music intervention between groups (two-way ANOVA-Tukey p<0.05, RStudio).

Results

Significantly lower anxiety level values were observed at 432 Hz (8.7±2.67) and 440 Hz (8.4±2.84) compared to the control group (17.2±4.60; p<0.05). The salivary cortisol level at 432 Hz (0.49±0.37 μg/dL) was significantly lower than 440 Hz (1.35±0.69 μg/dL) and the control group (1.59±0.7 μg/dL; p<0.05).

Conclusion

The use of music significantly decreased clinical anxiety levels, and the frequency of 432 Hz was effective in decreasing salivary cortisol levels before tooth extraction.

Ghrelin fiber projections from the hypothalamic arcuate nucleus into the dorsal vagal complex and the regulation of glycolipid metabolism

OBJECTIVES

This study aimed to explore the involvement of the ghrelin pathway from the arcuate nucleus (ARC) to the dorsal vagal complex (DVC) and to determine its role in the regulation of glycolipid metabolism.

METHODS

The protein and mRNA expression of ghrelin and growth hormone (GH) secretagogue receptor type 1a (GHSR-1a) were measured using immunohistochemistry and the polymerase chain reaction (PCR) method, respectively. Ghrelin fiber projections arising from the ARC and projecting into the DVC were investigated using retrograde tracing, combined with fluorescence immunohistochemical staining. The effects of electrical stimulation (ES) of the ARC on ghrelin-responsive, glucose-sensitive DVC neurons, glycolipid metabolism, and liver lipid enzymes were determined using electrical physiological method, biochemical analysis, quantitative real-time PCR (qRT-PCR) and Western blot analysis.

RESULTS

GHSR-1a was expressed in the DVC neurons. Ghrelin fibers originating from the ARC projected into the DVC. ES of the ARC-activated the ghrelin-responsive glucose-excited (GE) and glucose-inhibited (GI) neurons in the DVC. ES of the ARC significantly elevated the serum triglyceride (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and glucose levels; it reduced the serum high-density lipoprotein (HDLC) and insulin levels. Moreover, ES of the ARC increased liver acetyl-CoA carboxylase-1 (ACC-1) and decreased carnitine palmitoyltransferase-1 (CPT-1) expression, resulting in lipid accumulation in the liver. All the aforementioned effects were partially blocked by pretreatment with the ghrelin receptor antagonist [D-Lys-3]-GHRP-6 in the DVC and were reduced by vagotomy. ES of the ARC increased agouti-related protein (AgRP)/neuropeptide Y (NPY) expression in the ARC and ghrelin expression in the DVC.

CONCLUSION

Ghrelin fiber projections arising from the ARC and projecting into the DVC play a role in the regulation of afferent glucose metabolism and glycolipid metabolism via the ghrelin receptor GHSR-1a in the DVC.

Ghrelin and electrical stimulating the lateral hypothalamus area regulated the discharges of gastric distention neurons via the dorsal vagal complex in cisplatin-treated rats

OBJECTIVE

Cisplatin is an important antineoplastic drug and has side effects such as nausea, vomiting, and dyspepsia. The detailed mechanisms for its side effects are yet not well be illustrated. Our purpose was to investigate the discharges of gastric distention (GD) sensitive neurons regulated by ghrelin and electrical stimulation of the lateral hypothalamus area (LHA) via the dorsal vagal complex (DVC) in cisplatin-treated rats.

MATERIALS AND METHODS

Extracellular discharge recording was performed to observe the effects of ghrelin and electrical stimulation of the LHA on discharges of GD neurons in the DVC.

RESULTS

GD neurons were recorded in DVC in saline-treated and cisplatin-treated rats and identified as GD-excitatory (GD-E) neurons, which are excited by gastric distension, and GD-inhibitory (GE-I) neurons, which are inhibited by gastric distension. Microinjection of ghrelin into the DVC increased the firing frequency of most GD neurons, while the ratios of excited GD-E and GD-I neurons in cisplatin-treated rats were significantly lower than those in saline-treated rats. The excitatory effect of ghrelin was eliminated completely by DVC pretreatment with ghrelin receptor antagonist [D-Lys-3]-GHRP-6. After electrical stimulation of the LHA, the firing frequency of these neurons significantly increased. This excitatory effect was weaker in cisplatin-treated rats than in saline-treated rats and could be partly blocked by DVC pretreatment with [D-Lys-3]-GHRP-6.

CONCLUSION

GD neurons in the DVC could be excited by microinjecting ghrelin into the DVC and electrical stimulation of the LHA, respectively. The excitatory effect was attenuated by cisplatin injected intraperitoneally.

An investigation into the use of recorded music as a surgical intervention: A systematic, critical review of methodologies used in recent adult controlled trials

CONTEXT

While music is being increasingly used as a surgical intervention, the types of music used and the reasons underlying their selection remain inconsistent. Empirical research into the efficacy of such musical interventions is therefore problematic.

OBJECTIVE

To provide clear guidelines for musical selection and employment in surgical interventions, created through a synthesis of the literature. The aim is to examine how music is implemented in surgical situations, and to provide guidance for the selection and composition of music for future interventions.

METHODS

English language quantitative surgical intervention studies from Science Direct, ProQuest, and Sage Journals Online, all published within the last 10 years and featuring recorded music, were systematically reviewed. Variables investigated included: the time the intervention was performed, the intervention length, the outcomes targeted, music description (general and specific), theoretical frameworks underlying the selection of the music, whether or not a musical expert was involved, participant music history, and the participants' feedback on the chosen music.

RESULTS

Several aspects contribute to the lack of scientific rigour regarding music selection in this field, including the lack of a theoretical framework or frameworks, no involvement of musical experts, failure to list the music tracks used, and the use of vague and subjective terms in general music descriptions. Patients are frequently allowed to select music (risking both choosing music that has an adverse effect and making study replication difficult), and patient music history and listening habits are rarely considered. Crucially, five primary theoretical frameworks underlying the effectiveness of music arose in the literature (distraction, relaxation, emotional shift, entrainment, and endogenous analgesia), however music was rarely selected to enhance any of these mechanisms.

CONCLUSIONS

Further research needs to be conducted to ensure that music is selected according to a theoretical framework and more rigorous and replicable methodology. Music interventions can be made more effective at improving psychological states and reducing physiological arousal by selecting music conducive to specific mechanisms, and also by considering at what point during the surgical experience the music would be most effective. Greater involvement of music experts in interventions would help to ensure that the most appropriate music was chosen, and that it is clearly and precisely described.