Bulleyaconitine A Inhibits Itch and Itch Sensitization Induced by Histamine and Chloroquine

Mechanism of medical hemorrhoid gel in relieving pruritus ani via inhibiting the activation of JAK2/STAT3 pathway

Background

Pruritus ani (PA), a neurofunctional dermatosis, is one of the most common complications of hemorrhoids, which seriously affects the quality of life of patients. Medical hemorrhoid gel (MHG), a product mainly composed of herbal medicine, is widely used for treatment of PA clinically. This study aim to assess the alleviating effect and mechanism of MHG on PA based on rectal epidermis-spinal cord-brain axis using animal models.

Methods

A chloroquine-induced mouse itching model and a croton oil preparation-induced rat hemorrhoid model were established to evaluate anti-PA effect of MHG. Scratching behaviors of mice were recorded, and histopathology of mice skin and rat ano-rectal tissues was observed through H&E staining. Network pharmacology and western blotting were employed to explore potential mechanism of MHG.

Results

The study indicated that MHG significantly alleviated chloroquine-induced skin itching and improved pathological injuries in mice skin and rat ano-rectal tissues. Network pharmacology suggested that MHG might regulate the JAK/STAT signaling pathway. Experimental findings showed that MHG significantly downregulated TRPV1 and TRPA1 in rectal tissue, c-Fos and GRPR in spinal cord tissue, and 5-HT1a protein in brain tissue, while upregulating TRPM8 protein in rectal tissue. Furthermore, MHG inhibited the activation of the JAK2/STAT3 signaling pathway in the rectal epidermis-spinal cord-brain axis.

Conclusion

MHG improves PA by inhibiting the transmission of itching signals in rectal epidermis-spinal cord-brain axis via the JAK2/STAT3 signaling pathway, providing experimental evidence for its clinical application.

Hypothalamic response with PKA/CREB signaling is associated with direct cerebroventricular administration of bombesin-induced scratching

Bombesin (BN) is an itch-specific mediator that causes intense itch-scratching activity in mammals. Although most examinations of BN-induced itch processing have focused on the spinal cord, the involvement of central nervous system mechanisms remains unclear. Here, we investigated how relationships among hypothalamic regions regulate BN-mediated itch-scratch processes. We found that intracerebroventricular (i.c.v.) administration of BN (0.04-4 μg) elicited intense itch scratching in mice, whereas BN (0.4-400 μg) administered via intravenous tail injection failed to evoke a scratching response. Additionally, nalfurafine had no significant effects on BN-induced scratching behavior, indicating that central modulation of BN is distinct from histamine-mediated histaminergic itch and chloroquine-mediated non-histaminergic itch signaling pathways. We labeled BN with a fluorescent tag, 7-nitrobenz-2-oxa-1 (NBD), and traced its fluorescence in the hypothalamus for 30 min following i.c.v. NBD-BN administration. Accordingly, we confirmed that i.c.v. administration of BN enhanced c-Fos expression in the dorsal medial nucleus of the hypothalamus, where neuromedin B receptors and gastrin-releasing peptide receptors are highly expressed. Interestingly, in situ injection of BN into the hypothalamus immediately and robustly induced itch-scratching behavior. Moreover, gene transcripts and western blot assay revealed that BN receptor-dependent PKA/CREB signaling was upregulated in the hypothalamus after i.c.v. administration of BN. Consistently, pretreatment with a PKA inhibitor, Rp-cAMP, significantly reduced BN-induced scratching behavior. Our results indicate that the dorsal medial nucleus of the hypothalamus may be a key nucleus in mediating BN-mediated itch and hypothalamic PKA/CREB signaling is involved in regulating BN-mediated itch.

Emerging Therapeutic Options for Chronic Pruritus

Chronic pruritus, defined as an unpleasant sensation resulting in a need to scratch that lasts more than 6 weeks, is a prevalent and bothersome symptom associated with both cutaneous and systemic conditions. Due to complex pathogenesis and profuse contributing factors, chronic pruritus therapy remains challenging. Regardless of the well-established antipruritic properties of classic pharmacotherapy (topical therapy, phototherapy and systemic therapy), these methods often provide insufficient relief for affected individuals. Owing to the growing interest in the field of pruritic research, further experimental and clinical data have emerged, continuously supporting the possibility of instigating novel therapeutic measures. This review covers the most relevant current modalities remaining under investigation that possess promising perspectives of approval in the near future, especially opioidergic drugs (mu-opioid antagonists and kappa-opioid agonists), neurokinin-1 receptor antagonists, biologic drugs, Janus kinase inhibitors, ileal bile acid transporter inhibitors, aryl hydrocarbon receptor agonists and histamine H₄ receptor antagonists.

Bulleyaconitine A inhibits the lung inflammation and airway remodeling through restoring Th1/Th2 balance in asthmatic model mice

The current study aimed to study the effects of Bulleyaconitine A (BLA) on asthma. Asthmatic mice model was established by ovalbumin (OVA) stimulation, and the model mice were treated by BLA. After BLA treatment, the changes in lung and airway resistances, total and differential leukocytes in the bronchoalveolar lavage fluid (BALF) were detected, and the changes in lung inflammation and airway remodeling were observed. Moreover, the secretion of IgE, Th1/Th2-type and IL-17A cytokines in BALF and serum of the asthmatic mice were determined. The resuts showed that BLA attenuated OVA-induced lung and airway resistances, inhibited the inflammatory cell recruitment in BALF and the inflammation and airway remodeling of the asthmatic mice. In addition, BLA suppressed the secretion of IgE, Th2-type cytokines, and IL-17A, but enhanced secretions of Th1-type cytokines in BALF and serum. The current study discovered that BLA inhibited the lung inflammation and airway remodeling via restoring the Th1/Th2 balance in asthmatic mice.