Unmyelinated non-peptidergic nociceptors (NP afferents) arborise in lamina II of the spinal cord and receive GABAergic axoaxonic synapses, which mediate presynaptic inhibition. However, until now the source of this axoaxonic synaptic input was not known. Here we provide evidence that it originates from a population of inhibitory calretinin-expressing interneurons (iCRs), which correspond to lamina II islet cells. The NP afferents can be assigned to 3 functionally distinct classes (NP1-3). NP1 afferents have been implicated in pathological pain states, while NP2 and NP3 afferents also function as pruritoceptors. Our findings suggest that all 3 of these afferent types innervate iCRs and receive axoaxonic synapses from them, providing feedback inhibition of NP input. The iCRs also form axodendritic synapses, and their targets include cells that are themselves innervated by the NP afferents, thus allowing for feedforward inhibition. The iCRs are therefore ideally placed to control the input from non-peptidergic nociceptors and pruritoceptors to other dorsal horn neurons, and thus represent a potential therapeutic target for the treatment of chronic pain and itch.
Background: Mitragyna speciosa Korth or Kratom is widely used traditionally for its medicinal values. The major alkaloid content of kratom leaves is mitragynine, which binds to opioid receptors to give opioid-like effects. This study aimed to analyse the brain proteome of animals that displayed addictive behaviors. Design and Methods: Six groups (n=6-8) of rats made up of negative control, positive control using morphine (10 mg/kg), and treatment groups at low (1mg/kg) and high doses of mitragynine (30 mg/kg) for 1 and 4 days. The rats' behaviors were evaluated and subsequently the rats' brains were harvested for proteomic analysis that was performed by using 2D gel electrophoresis and LC/MS/MS. Results: The rats developed physical dependence only on day 4 following morphine and mitragynine (1 and 30mg/kg) treatments. Among the proteins that were up-regulated in treatment groups were four calcium-binding proteins, namely calretinin, F-actin, annexin A3 and beta-centractin. Conclusions: Upregulation of calretinin acted as low Ca2+ buffering upon the blockage of Ca2+ ion channel by mitragynine in the brain, which subsequently caused a reduction of GABA released and inversely increased the dopamine secretions that contributed to dependence indicators.
Hirschsprung's Disease (HD) is a congenital disorder causing severe constipation in infants and children. Suction rectal biopsy (SRB) is the preferred technique for obtaining tissue samples for histopathological evaluation. In low-resource settings like Malaysia, cost-effective diagnostic approaches are necessary, making single sample SRB valuable. This study evaluates the diagnostic accuracy and sufficiency of a single macroscopically adequate sample in suction rectal biopsies for the histopathological confirmation of HD. We conducted a retrospective study of children who underwent suction rectal biopsies for the diagnosis of HD at Hospital Raja Perempuan Zainab II (HRPZII), Kota Bharu, Kelantan. A total of 68 patients were included in the study. The inadequacy rate for bedside SRB was 14%, comparable to current literature. Our study found no statistically significant association between sample inadequacy and gestational age, gender, birth weight, or weight at biopsy. Complication rates were 0%, consistent with literature reports. Calretinin staining, an additional technique, was performed in 23 biopsy episodes, with a 4.3% inadequacy rate, compared to 20% in specimens not subjected to calretinin staining. The cost of SRB almost doubled with each additional sample taken, significant in low-resource environments. In conclusion, single sample SRBs can be adequately diagnostic and cost-effective in low-resource settings, providing valuable insights for healthcare facilities in Malaysia and other developing countries. The use of adjunctive techniques such as calretinin staining may improve diagnostic accuracy while maintaining cost-effectiveness. Further prospective studies with larger sample sizes are needed to validate these findings.
A potential cure for hearing loss would be to regenerate hair cells by stimulating cells of the damaged inner ear sensory epithelia to proliferate and differentiate into hair cells. Here, we investigated the possibility to isolate, culture-expand and characterize the cells from the cochlea membrane of adult mice. Our results showed that the cultured cells isolated from mouse cochlea membrane were heterogenous in nature. Morphologically there were epithelial like cells, hair cell like, nerve cell like and fibroblastic cells observed in the culture. The cultured cells were immunopositive for specific hair cell markers including Myosin 7a, Calretinin and Espin.