Self-inflicted Stabbings as Nonfatal Suicide Attempts: A Systematic Review and Case Series.

BACKGROUND: Suicide by cutting or piercing is a rare and often nonlethal method. Self-stabbings are a subset of these cases, which can lead to significant injuries. Current literature does not adequately summarize the psychiatric characteristics of this population. OBJECTIVE: To examine the psychiatric presentations of adults with nonfatal self-inflicted stabbing suicide attempts to better inform the evidence-based care provided by the psychiatric consult service. METHODS: We searched Embase, Ovid MEDLINE, APA Psych INFO, and CINAHL for studies published within the last 15 years. All full-article case reports, case series, cohort studies, and systematic literature reviews in English were included. Studies not specific to adult (only those >18 years old were included) patients with self-inflicted stabbing wounds were excluded. Included studies were separated into 2 groups: case reports and cohort studies. Simple summative statistical analyses were performed. The quality of evidence was assessed using a modified version of the Joanna Briggs Institute Critical Appraisal Tools. RESULTS: Thirty-four case reports, 3 cohort studies, and zero systematic literature reviews met the inclusion and quality assessment criteria. A total of 184 cases of self-stabbing were identified, 66% of which included male patients. The mean age of cohort patients was 44 years. The mean age of case report patients was 47 years. The most common tool for stabbing was a knife. Common stabbing locations included the neck, chest, and abdomen. Commonly reported psychiatric diagnoses included mood disorders and schizophrenia spectrum disorders. Self-stabbing characteristics important to psychiatry were inconsistently reported across studies. CONCLUSIONS: This literature review found that self-stabbing appears to be a male-preferred method and may be associated with mood disorders. Inconsistent reporting of relevant psychiatric data such as psychiatric diagnosis, previous psychiatric history, suicidal intent, and intoxication is present in our review and is potentially due to a lack of reports from the psychiatric perspective. This limits our understanding of psychiatric issues in adults who made nonfatal self-inflicted stabbing suicide attempts. A further study into the presentations of this population is needed to better understand this distinct group of patients.

Serotonin Disinhibits a Caenorhabditis elegans Sensory Neuron by Suppressing Ca2+-Dependent Negative Feedback.

Neuromodulators, such as serotonin (5-HT), alter neuronal excitability and synaptic strengths, and define different behavioral states. Neuromodulator-dependent changes in neuronal activity patterns are frequently measured using calcium reporters because calcium imaging can easily be performed on intact functioning nervous systems. With only 302 neurons, the nematode Caenorhabditis elegans provides a relatively simple, yet powerful, system to understand neuromodulation at the level of individual neurons. C. elegans hermaphrodites are repelled by 1-octanol, and the initiation of these aversive responses is potentiated by 5-HT. 5-HT acts on the ASH polymodal nociceptors that sense the 1-octanol stimulus. Surprisingly, 5-HT suppresses ASH Ca2+ transients while simultaneously potentiating 1-octanol-dependent ASH depolarization. Here we further explore this seemingly inverse relationship. Our results show the following (1) 5-HT acts downstream of depolarization, through Gαq-mediated signaling and calcineurin, to inhibit L-type voltage-gated Ca2+ channels; (2) the 1-octanol-evoked Ca2+ transients in ASHs inhibit depolarization; and (3) the Ca2+-activated K+ channel, SLO-1, acts downstream of 5-HT and is a critical regulator of ASH response dynamics. These findings define a Ca2+-dependent inhibitory feedback loop that can be modulated by 5-HT to increase neuronal excitability and regulate behavior, and highlight the possibility that neuromodulator-induced changes in the amplitudes of Ca2+ transients do not necessarily predict corresponding changes in depolarization.SIGNIFICANCE STATEMENT Neuromodulators, such as 5-HT, modify behavior by regulating excitability and synaptic efficiency in neurons. Neuromodulation is often studied using Ca2+ imaging, whereby neuromodulator-dependent changes in neuronal activity levels can be detected in intact, functioning circuits. Here we show that 5-HT reduces the amplitude of depolarization-dependent Ca2+ transients in a C. elegans nociceptive neuron, through Gαq signaling and calcineurin but that Ca2+ itself inhibits depolarization, likely through Ca2+-activated K+ channels. The net effect of 5-HT, therefore, is to increase neuronal excitability through disinhibition. These results establish a novel 5-HT signal transduction pathway, and demonstrate that neuromodulators can change Ca2+ signals and depolarization amplitudes in opposite directions, simultaneously, within a single neuron.