Participation of brainstem monoaminergic nuclei in behavioral depression

Cannabigerol modulates α2-adrenoceptor and 5-HT1A receptor-mediated electrophysiological effects on dorsal raphe nucleus and locus coeruleus neurons and anxiety behavior in rat

The pharmacological profile of cannabigerol (CBG), which acid form constitutes the main precursor of the most abundant cannabinoids, has been scarcely studied. It has been reported to target α2-adrenoceptor and 5-HT1A receptor. The locus coeruleus (LC) and the dorsal raphe nucleus (DRN) are the main serotonergic (5-HT) and noradrenergic (NA) areas in the rat brain, respectively. We aimed to study the effect of CBG on the firing rate of LC NA cells and DRN 5-HT cells and on α2-adrenergic and 5-HT1A autoreceptors by electrophysiological techniques in male Sprague-Dawley rat brain slices. The effect of CBG on the novelty-suppressed feeding test (NSFT) and the elevated plus maze test (EPMT) and the involvement of the 5-HT1A receptor was also studied. CBG (30 μM, 10 min) slightly changed the firing rate of NA cells but failed to alter the inhibitory effect of NA (1-100 µM). However, in the presence of CBG the inhibitory effect of the selective α2-adrenoceptor agonist UK14304 (10 nM) was decreased. Perfusion with CBG (30 μM, 10 min) did not change the firing rate of DRN 5-HT cells or the inhibitory effect of 5-HT (100 μM, 1 min) but it reduced the inhibitory effect of ipsapirone (100 nM). CBG failed to reverse ipsapirone-induced inhibition whereas perfusion with the 5-HT1A receptor antagonist WAY100635 (30 nM) completely restored the firing rate of DRN 5-HT cells. In the EPMT, CBG (10 mg/kg, i.p.) significantly increased the percentage of time the rats spent on the open arms and the number of head-dipping but it reduced the anxiety index. In the NSFT, CBG decreased the time latency to eat in the novel environment but it did not alter home-cage consumption. The effect of CBG on the reduction of latency to feed was prevented by pretreatment with WAY100635 (1 mg/kg, i.p.). In conclusion, CBG hinders the inhibitory effect produced by selective α2-adrenoceptor and 5-HT1A receptor agonists on the firing rate of NA-LC and 5-HT-DRN neurons by a yet unknown indirect mechanism in rat brain slices and produces anxiolytic-like effects through 5-HT1A receptor.

Genetic identification of a population of noradrenergic neurons implicated in attenuation of stress-related responses

Noradrenergic signaling plays a well-established role in promoting the stress response. Here we identify a subpopulation of noradrenergic neurons, defined by developmental expression of Hoxb1, that has a unique role in modulating stress-related behavior. Using an intersectional chemogenetic strategy, in combination with behavioral and physiological analyses, we show that activation of Hoxb1-noradrenergic (Hoxb1-NE) neurons decreases anxiety-like behavior and promotes an active coping strategy in response to acute stressors. In addition, we use cerebral blood volume-weighted functional magnetic resonance imaging to show that chemoactivation of Hoxb1-NE neurons results in reduced activity in stress-related brain regions, including the bed nucleus of the stria terminalis, amygdala, and locus coeruleus. Thus, the actions of Hoxb1-NE neurons are distinct from the well-documented functions of the locus coeruleus in promoting the stress response, demonstrating that the noradrenergic system contains multiple functionally distinct subpopulations.

Influence of Cognitive Behavioral Therapy on Mood and Quality of Life After Stent Implantation in Young and Middle-Aged Patients With Coronary Heart Disease

Cognitive behavioral therapy (CBT), established only a few decades ago, is widely used by clinical psychologists. This study aimed to investigate the effects of CBT on mental status and quality of life (QOL) after percutaneous coronary intervention (PCI) in young and middle-aged patients with coronary heart disease (CHD). Seventy-five anxiety/depression patients (mean age, 52.2 ± 6.2 years, including 8 individuals < 45 years old) with CHD treated with PCI were randomly divided into a CBT group (n = 38) and control group (n = 37). The CBT group received 8 weeks of CBT in addition to the routine postoperative treatment that was also administered to control patients. The 17-item Hamilton Depression Rating Scale (HAM-D17), Hamilton anxiety scale (HAM-A), and Coronary Revascularization Outcome Questionnaire (CROQ-PTCA-POST, Chinese version) were administered before, 3 days, and 8 weeks after intervention. HAM-D17 and HAM-A scores were decreased after treatment, but were more substantially reduced in patients that underwent CBT than those in the control group (11.7 ± 4.5 versus 15.1 ± 3.9, P = 0.001 and 10.6 ± 3.4 versus 16.5 ± 4.6, P = 0.003, respectively). QOL was improved in both groups, but overall satisfaction was higher in the CBT group compared with control patients (89.3 ± 5.2 versus 77.8 ± 9.5, P < 0.05). CBT can relieve depression and anxiety after PCI in young and middle-aged patients with CHD. CBT can improve patient QOL.

Differential neuroprotective and anti-inflammatory effects of L-type voltage dependent calcium channel and ryanodine receptor antagonists in the substantia nigra and locus coeruleus

Neuroinflammation and degeneration of catecholaminergic brainstem nuclei occur early in neurodegenerative diseases such as Alzheimer's disease and Parkinson's disease. Neuroinflammation increases levels of pro-inflammatory cytokines and reactive oxygen species which can alter neuronal calcium (Ca(+2)) homoeostasis via L-type voltage dependent calcium channels (L-VDCCs) and ryanodine receptors (RyRs). Alterations in Ca(+2) channel activity in the SN and LC can lead to disruption of normal pacemaking activity in these areas, contributing to behavioral deficits. Here, we utilized an in vivo model of chronic neuroinflammation: rats were infused intraventricularly with a continuous small dose (0.25 μg/h) of lipopolysaccharide (LPS) or artificial cerebrospinal fluid (aCSF) for 28 days. Rats were treated with either the L-VDCC antagonist nimodipine or the RyR antagonist dantrolene. LPS-infused rats had significant motor deficits in the accelerating rotarod task as well as abnormal behavioral agitation in the forced swim task and open field. Corresponding with these behavioral deficits, LPS-infused rats also had significant increases in microglia activation and loss of tyrosine hydroxylase (TH) immunoreactivity in the substantia nigra pars compacta (SNpc) and locus coeruleus (LC). Treatment with nimodipine or dantrolene normalized LPS-induced abnormalities in the rotarod and forced swim, restored the number of TH-immunoreactive cells in the LC, and significantly reduced microglia activation in the SNpc. Only nimodipine significantly reduced microglia activation in the LC, and neither drug increased TH immunoreactivity in the SNpc. These findings demonstrate that the Ca(+2) dysregulation in the LC and SN brainstem nuclei is differentially altered by chronic neuroinflammation. Overall, targeting Ca + 2 dysregulation may be an important target for ameliorating neurodegeneration in the SNpc and LC.