Nitric oxide synthases: A delicate dance between bone regeneration and neuronal birth

Spinal cord injury (SCI) is a devastating condition resulting from traumatic or nontraumatic injury/chronic disorder. The pathogenesis of SCI necessitates a comprehensive approach, as it involves therapeutic strategies addressing both bone (spine) and neural (spinal cord) damage. This review centers on the pivotal role of nitric oxide (NO) and its synthesizing enzymes, nitric oxide synthases (NOS), in mediating the crosstalk between osteogenesis and neurogenesis. NO's effects are context-dependent, exhibiting a delicate balance between beneficial and detrimental actions. Reduced levels of nitric oxide (NO), primarily derived from endothelial NOS (eNOS), tipically stimulate osteoblast activity and promote neurogenesis by influencing neural stem cell (NSC) migration and differentiation. Conversely, elevated NO levels, predominantly from inducible NOS (iNOS), tipically triggered by inflammation, inhibit both processes through pro-apoptotic mechanisms. Nevertheless, these phenomena are not merely simplistic; they can be influenced by a variety of other factors. We explore the intricate interplay of NO/NOS with key signaling pathways crucial in neurogenesis and osteogenesis, including mechanical stimuli, Wnt, interleukins, BMPs, NF-κB, etc., revealing their influence on neuroinflammation, neurogenesis, and osteoblast differentiation. The temporal and spatial dynamics of NO/NOS activity and the implications for therapeutic intervention have been discussed. Precise modulation of NO levels and NOS isoforms, potentially through targeted therapies manipulating these interacting signaling pathways, emerges as a promising strategy for promoting bone and neural regeneration. This review highlights the critical need for a balanced approach in therapeutic strategies to harness the beneficial effects of NO/NOS while mitigating its detrimental consequences.

Stimulation of brain corticotropin-releasing factor receptor type1 facilitates the rat micturition via brain glutamatergic receptors

Corticotropin-releasing factor (CRF), a representative stress-related neuropeptide, in the central nervous system reportedly both facilitates and suppresses the micturition, therefore, roles of central CRF in regulation of the micturition are still controversial. In this study, we investigated (1) effects of intracerebroventricularly (icv)-administered CRF on the micturition, and (2) brain CRF receptor subtypes (CRFR1/CRFR2) and glutamatergic receptors (NMDA/AMPA subtypes) involved in the CRF-induced effects in male Wistar rats under urethane anesthesia. Intercontraction intervals (ICI), and maximal voiding pressure (MVP), were evaluated by continuous cystometry 45 min before CRF administration or intracerebroventricular pretreatment with other drugs as follows and 3 h after CRF administration. Single-voided volume (Vv), post-voiding residual volume (Rv), bladder capacity (BC), and voiding efficiency (VE) were evaluated by single cystometry 60 min before CRF administration and 60-120 min after the administration. Icv-administered CRF reduced ICI, Vv, and BC without changing MVP, Rv, or VE. The CRF-induced ICI reduction was attenuated by icv-pretreated CP154526 (CRFR1 antagonist), MK-801 (NMDA receptor antagonist), and DNQX (AMPA receptor antagonist), but not by K41498 (CRFR2 antagonist). These results indicate that stimulation of brain CRFR1 can be involved in facilitation of the rat micturition via brain NMDA/AMPA receptors.

Psychological/mental stress-induced effects on urinary function: Possible brain molecules related to psychological/mental stress-induced effects on urinary function

Exposure to psychological/mental stress can affect urinary function, and lead to and exacerbate lower urinary tract dysfunctions. There is increasing evidence showing stress-induced changes not only at phenomenological levels in micturition, but also at multiple levels, lower urinary tract tissues, and peripheral and central nervous systems. The brain plays crucial roles in the regulation of the body's responses to stress; however, it is still unclear how the brain integrates stress-related information to induce changes at these multiple levels, thereby affecting urinary function and lower urinary tract dysfunctions. In this review, we introduce recent urological studies investigating the effects of stress exposure on urinary function and lower urinary tract dysfunctions, and our recent studies exploring "pro-micturition" and "anti-micturition" brain molecules related to stress responses. Based on evidence from these studies, we discuss the future directions of central neurourological research investigating how stress exposure-induced changes at peripheral and central levels affect urinary function and lower urinary tract dysfunctions. Brain molecules that we explored might be entry points into dissecting the stress-mediated process for modulating micturition.