Long-term depression (LTD) in sensory cortices depends on the activation of NMDA receptors. Here, we report that in visual cortical slices, the induction of LTD (but not long-term potentiation) also requires the activation of receptors coupled to the phospholipase C (PLC) pathway. Using immunolesions in combination with agonists and antagonists, we selectively manipulated the activation of α1 adrenergic, M1 muscarinic, and mGluR5 glutamatergic receptors. Inactivation of these PLC-coupled receptors prevents the induction of LTD, but only when the three receptors were inactivated together. LTD is fully restored by activating any one of them or by supplying intracellulard-myo-inositol-1,4,5-triphosphate (IP₃). LTD was also impaired by intracellular application of PLC or IP₃receptor blockers, and it was absent in mice lacking PLCβ1, the predominant PLC isoform in the forebrain. We propose that visual cortical LTD requires a minimum of PLC activity that can be supplied independently by at least three neurotransmitter systems. This essential requirement places PLC-linked receptors in a unique position to control the induction of LTD and provides a mechanism for gating visual cortical plasticity via extra-retinal inputs in the intact organism.

Carpal tunnel syndrome (CTS) is a common peripheral neuropathy and ischemic-reperfusion injury. Oxidative stress is considered a major cause of CTS. Linalool, a component of essential oils, has antioxidant activity. This study was designed to determine the effects of linalool inhalation on oxidative stress in patients with CTS. This double-blind, placebo-controlled study assessed the effects of linalool inhalation on oxidative stress in patients with CTS. Thirty-seven subjects, with and without CTS, were randomized to inhalation of 1 % linalool or carrier oil. 1,1-Diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, systolic blood pressure (sBP), diastolic blood pressure (dBP) and pulse rate were analyzed. DPPH inhibition was significantly higher in both experimental groups than in their respective controls. Moreover inhalation of linalool reduced sBP, dBP and pulse rate in the CTS group, and pulse rate in the non-CTS group. However, there were no significant differences among the study groups in nitrite levels, sBP, dBP and pulse rate. Inhalation of linalool increases antioxidative activity and reduces blood pressure and pulse rate in patients with CTS.