Stimulation of CGRP-expressing neurons in the medial cerebellar nucleus induces light and touch sensitivity in mice.

Calcitonin gene-related peptide (CGRP) is considered a major player in migraine pathophysiology. However, the location and mechanisms of CGRP actions in migraine are not clearly elucidated. One important question yet to be answered is: Does central CGRP signaling play a role in migraine? One candidate site is the cerebellum, which serves as a sensory and motor integration center and is activated in migraine patients. The cerebellum has the most CGRP binding sites in the central nervous system and a deep cerebellar nucleus, the medial nucleus (MN), expresses CGRP (MNCGRP). A previous study demonstrated that CGRP delivery into the cerebellum induced migraine-like behaviors. We hypothesized that stimulation of MNCGRP neurons might induce migraine-like behaviors. To test the hypothesis, we used an optogenetic strategy using CalcaCre/+ mice to drive Cre-dependent expression of channelrhodopsin-2 selectively in CGRP neurons in the cerebellar MN. A battery of behavioral tests was done to assess preclinical behaviors that are surrogates of migraine symptoms, including light aversion, cutaneous allodynia, and spontaneous pain when MNCGRP neurons were optically stimulated. Motor functions were also assessed. Optical stimulation of MNCGRP neurons decreased the time spent in the light, which was coupled to increased time spent resting in the dark, but not the light. These changes were only significant in female mice. Plantar tactile sensitivity was increased in the ipsilateral paws of both sexes, but contralateral paw data were less clear. There was no significant increase in anxiety-like behavior, spontaneous pain (squint), or changes in gait. These discoveries reveal that MNCGRP neurons may contribute to migraine-like sensory hypersensitivity to light and touch.

Activation of Oxytocin Neurons Improves Cardiac Function in a Pressure-Overload Model of Heart Failure.

This work shows long-term restoration of the hypothalamic oxytocin (OXT) network preserves OXT release, reduces mortality, cardiac inflammation, fibrosis, and improves autonomic tone and cardiac function in a model of heart failure. Intranasal administration of OXT in patients mimics the short-term changes seen in animals by increasing parasympathetic-and decreasing sympathetic-cardiac activity. This work provides the essential translational foundation to determine if approaches that mimic paraventricular nucleus (PVN) OXT neuron activation, such as safe, noninvasive, and well-tolerated intranasal administration of OXT, can be beneficial in patients with heart failure.