Opioids Induce Bidirectional Synaptic Plasticity in a Brainstem Pain Center in the Rat.

Opioids are powerful analgesics commonly used in pain management. However, opioids can induce complex neuroadaptations, including synaptic plasticity, that ultimately drive severe side effects, such as pain hypersensitivity and strong aversion during prolonged administration or upon drug withdrawal, even following a single, brief administration. The lateral parabrachial nucleus (LPBN) in the brainstem plays a key role in pain and emotional processing; yet, the effects of opioids on synaptic plasticity in this area remain unexplored.

GABAergic CaMKIIα+ Amygdala Output Attenuates Pain and Modulates Emotional-Motivational Behavior via Parabrachial Inhibition.

Pain and emotion are strongly regulated by neurons in the central nucleus of the amygdala (CeA), a major output of the limbic system; yet, the neuronal signaling pathways underlying this modulation are incompletely understood. Here, we characterized a subpopulation of CeA neurons that express the CaMKIIα gene (CeA neurons) and project to the lateral parabrachial nucleus (LPBN), a brainstem region known for its critical role in distributing nociceptive and other aversive signals throughout the brain. In male Sprague Dawley rats, we show that CeA-LPBN neurons are GABAergic and mostly express somatostatin.

Anti-Nociceptive and Anti-Aversive Drugs Differentially Modulate Distinct Inputs to the Rat Lateral Parabrachial Nucleus.

The lateral parabrachial nucleus (LPBN) plays an important role in the processing and establishment of pain aversion. It receives direct input from the superficial dorsal horn and forms reciprocal connections with the periaqueductal grey matter (PAG), which is critical for adaptive behaviour and the modulation of pain processing. Here, using in situ hybridization and optogenetics combined with in vitro electrophysiology, we characterized the spinal- and PAG-LPBN circuits of rats.

Interferon-γ facilitates the synaptic transmission between primary afferent C-fibres and lamina I neurons in the rat spinal dorsal horn via microglia activation.

Recent studies have demonstrated an important role of the pro-inflammatory cytokine interferon-γ in neuropathic pain. Interferon-γ is upregulated in the lumbar spinal cord of nerve-injured rodents and intrathecal injection of interferon-γ has been shown to induce neuropathic pain-like behaviours in naive rodents. A potential mechanism in the pathogenesis of neuropathic pain is a long-lasting amplification of nociceptive synaptic transmission in lamina I of the spinal dorsal horn.

Common issues encountered in adolescent sports medicine: guide to completing the preparticipation physical evaluation.

Participation in athletic activities among children and adolescents is on the rise in the United States. Approximately 35 million children ages 5 to 18 play organized sports each year. High school athletes suffer approximately 2 million injuries per year, resulting in 500,000 doctor visits and 30,000 hospitalizations.