D2 dopamine receptor-mediated mechanisms of dopaminergic system modulation in in vivo and in vitro experimental models of migraine.

The dopaminergic system is implicated in the pathophysiology of migraine. However, the underlying mechanisms remain unclear. We explored the effects and mechanisms of dopaminergic system modulation in the in vivo and in vitro rat models of migraine. Dopaminergic agonist apomorphine, D2 receptor antagonists metoclopramide and haloperidol and 5-HT3 receptor antagonist ondansetron alone and together were tested in nitroglycerin-induced migraine model, in vivo. Likewise, the combinations of drugs were also tested on basal calcitonin gene-related peptide (CGRP) release in vitro hemiskull preparations. Mechanical allodynia was tested by von Frey filaments. CGRP concentrations in trigeminovascular structures and in vitro superfusates and c-Fos levels in the brainstem were determined by enzyme-linked immunosorbent assay. Meningeal mast cells were evaluated with toluidine blue staining. Apomorphine further enhanced nitroglycerin-induced mechanical allodynia, brainstem c-fos expression, trigeminal ganglion and brainstem CGRP concentrations and meningeal mast cell degranulation, in vivo. Haloperidol completely antagonised all apomorphine-induced effects and also alleviated changes induced by nitroglycerin without apomorphine. Metoclopramide and ondansetron partially attenuated apomorphine- or nitroglycerin-induced effects. A combination of haloperidol and ondansetron decreased basal CGRP release, in vitro, whereas the other administrations were ineffective. Apomorphine-mediated dopaminergic activation exacerbated nitroglycerin-stimulated nociceptive reactions by further enhancing c-fos expression, CGRP release and mast cell degranulation in strategical structures associated with migraine pain. Metoclopramide partially attenuated the effects of apomorphine, most likely because it is also a 5-HT3 receptor antagonist. Haloperidol with pure D2 receptor antagonism feature appears to be more effective than metoclopramide in reducing migraine-related parameters in dopaminergic activation- and/or NTG-induced migraine-like conditions.

The prevalence of vitamin D deficiency and the factors affecting vitamin D levels in children admitted to the outpatient clinic of pediatric endocrinology in Bolu Province.

BACKGROUND: The present study aimed to determine the rate of vitamin D deficiency in children who presented to the pediatric endocrinology outpatient clinic in Bolu and to investigate the factors affecting vitamin D levels. METHODS: Vitamin D levels of 1008 children and adolescents were retrospectively analyzed according to age group (0-1, 1-10, and 10-18 years), gender, season, month, obesity and other diseases, and deficiency category. Moreover, calcium, phosphorus, alkaline phosphatase, and parathyroid hormone levels were evaluated. Comparisons and correlation analyses between related groups were performed. RESULTS: The mean vitamin D level of the patients was 16.35±9.56 ng/mL and was lower in girls (14.90±9.56 ng/mL) than in boys (18.68±9.63 ng/mL, p<0.001). Overall, 18.3% of the children and adolescents had vitamin D insufficiency, 52.3% had vitamin D deficiency, and 3.5% had severe vitamin D deficiency. Vitamin D levels were lower in 10-18-year age group than in the other age groups (p<0.001), and levels were higher in summer and autumn than in winter and spring (p<0.001). Vitamin D levels of participants with obesity (14.3 ± 8.3 ng/mL) were significantly lower than normal-weight participants with no health problems (15.9 ± 8.3 ng/mL, p = 0.004). There was a negative correlation between vitamin D, alkaline phosphatase, and parathyroid hormone levels in the 1-10-year age group, but a positive correlation between vitamin D, alkaline phosphatase, and calcium levels in the 10-18-year age group. CONCLUSION: The rate of vitamin D deficiency is high among children and adolescents who presented to the endocrine outpatient clinic in Bolu. The season appears to be an important factor affecting vitamin D levels as well as the relationship between vitamin D and parathyroid hormone. Obese children and adolescents living in this region may be advised to take vitamin D supplements in winter and spring.

Capsaicin attenuates excitotoxic-induced neonatal brain injury and brain mast cell-mediated neuroinflammation in newborn rats.

Excitotoxicity and neuroinflammation are key contributors to perinatal brain injuries. Capsaicin, an active ingredient of chili peppers, is a potent exogenous agonist for transient receptor potential vanilloid 1 receptors. Although the neuroprotective and anti-inflammatory effects of capsaicin are well-documented, its effects on excitotoxic-induced neonatal brain injury and neuroinflammation have not previously been investigated. The aim of this study was to investigate the effects of capsaicin on brain damage, brain mast cells, and inflammatory mediators in a model of ibotenate-induced excitotoxic brain injury in neonatal rats. P5 rat-pups were intraperitoneally injected with vehicle, 0.2-, 1-, and 5-mg/kg doses of capsaicin, or the NMDA (N-methyl-d-aspartate) receptor antagonist MK-801 (dizocilpine), 30 min before intracerebral injection of 10 µg ibotenate. The naive-control group received no substance administration. The rat pups were sacrificed one or five days after ibotenate injection. Levels of activin A and interleukin (IL)-1ß, IL-6, and IL-10 in brain tissue were measured using the enzyme-linked immunosorbent assay method. Cortex and white matter thicknesses, white matter lesion size, and mast cells were evaluated in brain sections stained with cresyl-violet or toluidine-blue. Capsaicin improved ibotenate-induced white matter lesions and cerebral white and gray matter thicknesses in a dose-dependent manner. In addition, it suppressed the degranulation and increased number of brain mast cells induced by ibotenate. Capsaicin also reduced the excitotoxic-induced production of neuronal survival factor activin A and of the pro-inflammatory cytokines IL-1ß, and IL-6 in brain tissue. However, IL-10 levels were not altered by the treatments. MK-801, as a positive control, reversed all these ibotenate-induced changes, further confirming the success of the model. Our findings provide, for the first time, evidence for the therapeutic effects of capsaicin against excitotoxic-induced neonatal brain injury and brain mast cell-mediated neuroinflammation. Capsaicin may therefore be a promising candidate in the prevention and/or reduction of neonatal brain damage.

Esculetin alleviates pentylenetetrazole-induced seizures, cognitive impairment and pro-inflammatory cytokines and suppresses penicillin-induced epileptiform activity in rats.

AIMS: To investigate the effects of different doses of esculetin on epileptiform activity, behavioral seizures, memory impairment, and cortical and hippocampal NF-κB, as a mediator of pro-inflammatory gene induction, and pro-inflammatory cytokines in penicillin- and pentylenetetrazole(PTZ)-induced seizure models in rats. MAIN METHODS: Different doses of esculetin (5, 10, and 20 mg/kg), and diazepam (5 mg/kg) as a positive control, were tested in penicillin- and pentylenetetrazole(PTZ)-induced seizure models. In the PTZ model, cognitive function, behavioral seizures, and cortical and hippocampal pro-inflammatory biomarkers and survival factor was evaluated. In the penicillin model, the frequency and amplitude of electrophysiological epileptiform activity were assessed. KEY FINDINGS: In the PTZ model, the 10 mg/kg esculetin displayed anticonvulsant effects by extending onset-times of myoclonic-jerk and generalized tonic-clonic seizure, and by diminishing seizure severity and duration of generalized tonic-clonic seizure. It also ameliorated PTZ-induced cognitive impairment, and cortical and hippocampal activin-A, IL-1ß, IL-6 and NF-κB levels. In the penicillin model, the 10 mg/kg esculetin decreased the frequency of spikes without changing the amplitude of spikes. As a positive-control, diazepam reversed all changes induced by both PTZ and penicillin. SIGNIFICANCE: Esculetin exhibits anticonvulsant and memory-improving effects by alleviating the behavioral and electrophysiological characteristics of epileptic seizures. Additionally, esculetin exerts anti-neuroinflammatory actions in the PTZ-induced seizures model. Thus, esculetin may be a multi-targeted promising agent with anticonvulsant and anti-neuroinflammatory effects in the treatment of epilepsy.

Meningeal mast cell-mediated mechanisms of cholinergic system modulation in neurogenic inflammation underlying the pathophysiology of migraine.

Growing evidence indicates that the parasympathetic system is implicated in migraine headache. However, the cholinergic mechanisms in the pathophysiology of migraine remain unclear. We investigated the effects and mechanisms of cholinergic modulation and a mast cell stabilizer cromolyn in the nitroglycerin-induced in vivo migraine model and in vitro hemiskull preparations in rats. Effects of cholinergic agents (acetylcholinesterase inhibitor neostigmine, or acetylcholine, and muscarinic antagonist atropine) and mast cell stabilizer cromolyn or their combinations were tested in the in vivo and in vitro experiments. The mechanical hyperalgesia was assessed by von Frey hairs. Calcitonin gene-related peptide (CGRP) and C-fos levels were measured by enzyme-linked immunosorbent assay. Degranulation and count of meningeal mast cells were determined by toluidine-blue staining. Neostigmine augmented the nitroglycerin-induced mechanical hyperalgesia, trigeminal ganglion CGRP levels, brainstem CGRP, and C-fos levels, as well as degranulation of mast cells in vivo. Atropine inhibited neostigmine-induced additional increases in CGRP levels in trigeminal ganglion and brainstem while it failed to do this in the mechanical hyperalgesia, C-fos levels, and the mast cell degranulation. However, all systemic effects of neostigmine were abolished by cromolyn. The cholinergic agents or cromolyn did not alter basal release of CGRP, in vitro, but cromolyn alleviated the CGRP-inducing effect of capsaicin while atropine failed to do it. These results ensure for a first time direct evidence that endogenous acetylcholine contributes to migraine pathology mainly by activating meningeal mast cells while muscarinic receptors are involved in CGRP release from trigeminal ganglion and brainstem, without excluding the possible role of nicotinic cholinergic receptors.