Low Dose Of Pilocarpine Research Articles

Ураження нервової системи в пацієнта із синдромом Еді (клінічний випадок)

Синдром Еді (Adie-Holmes), або синдром тонічної зіниці, — стан, що характеризується тріадою основних симптомів: одностороннім тонічним розширенням зіниці, парезом акомодації з відсутністю або значним зменшенням реакції зіниці на світло і зниженням сухожильних рефлексів. В основі захворювання лежить порушення функції парасимпатичної нервової системи. Синдром виникає внаслідок ураження циліарного ганглія, що забезпечує парасимпатичну іннервацію м’яза зіниці (m. sphincter pupillae), рогівки й оболонки очного яблука. Нерідко стан супроводжується порушенням функції спінальних гангліїв і, як наслідок, вегетативною дисфункцією у вигляді розладу потовиділення, зазвичай на одній стороні тіла, рідше — розладом серцевого ритму, лабільністю артеріального тиску. Частий супутник синдрому Еді — відсутність або зниження колінних рефлексів, рідше — ахіллових. Етіологія захворювання остаточно не з’ясована, не виключений бактеріальний або вірусний чинник. Діагностика синдрому Еді переважно заснована на клінічному зіставленні симптомів захворювання, а також на ретельному й всебічному огляді нейроофтальмолога з обов’язковим проведенням тестування зіничних реакцій за допомогою низьких доз пілокарпіну (характерне звуження зіниці). Незважаючи на позитивний прогноз щодо життя хворого і його працездатності, стан належить до групи складнокурабельних, а лікування зводиться до симптоматичної корекції зору.

Prediction of GABA receptor antagonist-induced convulsion in cynomolgus monkeys by combining machine learning and heart rate variability analysis

Drug-induced convulsion is a severe adverse event; however, no useful biomarkers for it have been discovered. We propose a new method for predicting drug-induced convulsions in monkeys based on heart rate variability (HRV) and a machine learning technique. Because autonomic nervous activities are altered around the time of a convulsion and such alterations affect HRV, they may be predicted by monitoring HRV. In the proposed method, anomalous changes in multiple HRV parameters are monitored by means of a convulsion prediction model, and convulsion alarms are issued when abnormal changes in HRV are detected. The convulsion prediction model is constructed based on multivariate statistical process control (MSPC), a well-known anomaly detection algorithm in machine learning. In this study, HRV data were collected from four cynomolgus monkeys administered with multiple doses of pentylenetetrazol (PTZ) and picrotoxin (PTX), which are GABA receptor antagonists, as convulsant agents. In addition, low doses of pilocarpine (PILO) were administered as a negative control. Twelve HRV parameters in three hours after drug administration were monitored by means of the prediction model. The number and duration of convulsion alarms from HRV increased at medium and high doses of PTZ and PTX (1/3 or 1/4 of convulsion dose). On the other hand, the frequency of convulsion alarms did not increase with PILO. Although vomiting was observed in all drugs, convulsion alarms were not associated with the vomiting. Thus, convulsion alarms can be used as a biomarker for convulsions induced by GABA receptor antagonists.

Effects of L-type voltage-gated Ca2+ channel blockade on cholinergic and thermal sweating in habitually trained and untrained men.

We evaluated the hypothesis that the activation of L-type voltage-gated Ca2+ channels contributes to exercise training-induced augmentation in cholinergic sweating. On separate days, 10 habitually trained and 10 untrained men participated in two experimental protocols. Prior to each protocol, we administered 1% verapamil (Verapamil, L-type voltage-gated Ca2+ channel blocker) and saline (Control) at forearm skin sites on both arms via transdermal iontophoresis. In protocol 1, we administered low (0.001%) and high (1%) doses of pilocarpine at both the verapamil-treated and verapamil-untreated forearm sites. In protocol 2, participants were passively heated by immersing their limbs in hot water (43°C) until rectal temperature increased by 1.0°C above baseline resting levels. Sweat rate at all forearm sites was continuously measured throughout both protocols. Pilocarpine-induced sweating in Control was higher in trained than in untrained men for both the concentrations of pilocarpine (both P ≤ 0.001). Pilocarpine-induced sweating at the low-dose site was attenuated at the Verapamil versus the Control site in both the groups (both P ≤ 0.004), albeit the reduction was greater in trained as compared with in untrained men (P = 0.005). The verapamil-mediated reduction in sweating remained intact at the high-dose pilocarpine site in the untrained men (P = 0.004) but not the trained men (P = 0.180). Sweating did not differ between Control and Verapamil sites with increases in rectal temperature in both groups (interaction, P = 0.571). We show that activation of L-type voltage-gated Ca2+ channels modulates sweat production in habitually trained men induced by a low dose of pilocarpine. However, no effect on sweating was observed during passive heating in either group.

Lactation in large litters influences anxiety, memory, and spreading depression in adult male rats that were chronically subjected to a non-convulsive pilocarpine dose

ABSTRACT Objectives: Unfavorable lactation influences brain excitability and behavioral reactions in adults. Administration early in life of the cholinergic agonist, pilocarpine, even at non-convulsive doses, alters the brain excitability-related phenomenon known as cortical spreading depression (CSD), and produce anxiogenic-like behavior. However, the influence of unfavorable lactation on the CSD- and memory-effects of pilocarpine administration late in life has not been investigated. Herein, we analyzed the ponderal, electrophysiological (CSD), and behavioral effects of chronic treatment with a non-convulsive dose of pilocarpine, in adult rats suckled under favorable and unfavorable conditions. Methods: Wistar rats were suckled in litters with 9 or 15 pups (groups L9 and L15, respectively). A very low dose of pilocarpine (45/mg/kg/day) was chronically administered in mature rats from postnatal day (PND) 69–90. Behavioral tests occurred at PND91 [elevated plus maze (EPM)], PND93 [open field (OF)], and PND94–95 [object recognition memory (ORM)]. CSD was recorded between PND96–120. Results: Pilocarpine-treated rats performed worse in the anxiety and memory tests, and displayed lower CSD propagation velocity when compared with saline-treated controls. In addition, L15 rats showed an increase in the distance traveled and a decrease in the immobility time in the EPM, impaired ORM, and accelerated CSD propagation when compared with L9 rats (p ≤ 0.05). Discussion: These data suggest that sub-convulsive pilocarpine treatment in adult rats can affect behavioral and excitability-related reactions. In addition, unfavorable lactation increases the ambulatory effects of pilocarpine. Further studies should investigate the possible cholinergic molecular mechanisms involved in these effects.

Cortical network dynamics are coupled with cognitive aging in rats.

Changes in neuronal network activity and increased interindividual variability in memory are among the most consistent features of growing older. Here, we examined the relationship between these hallmarks of aging. Young and aged rats were trained on a water maze task where aged individuals reliably display an increased range of spatial memory capacities relative to young. Two weeks later, neuronal activity was induced pharmacologically with a low dose of pilocarpine and control animals received vehicle. Activity levels were proxied by quantifying the immediate early gene products Arc and c-Fos. While no relationship was observed between basal, resting activity, and individual differences in spatial memory in any brain region, pilocarpine-induced marker expression was tightly coupled with memory in all areas of the prefrontal cortex (PFC) and hippocampus examined. The nature of this association, however, differed across regions and in relation to age-related cognitive outcome. Specifically, in the medial PFC, induced activity was greatest in aged rats with cognitive impairment and correlated with water maze performance across all subjects. In the hippocampus, the range of induced marker expression was comparable between groups and similarly coupled with memory in both impaired and unimpaired aged rats. Together the findings highlight that the dynamic range of neural network activity across multiple brain regions is a critical component of neurocognitive aging.

A novel method for measuring small amounts of saliva in mice

AbstractDry mouth is caused by the dysfunction of salivary glands due to various factors. In order to understand the mechanism of dry mouth or develop new therapies for dry mouth, many mice models have been widely used to analyze the function of saliva secretion. In this study, a small amount of saliva was collected using oral pH paper, following stimulation with a low dose of pilocarpine in mice. The method is simple and accurate for the evaluation of small volumes of saliva secretion following weak stimulation in mice. Thus, a simple method would be useful during experiments using mice for detection of small volumes of saliva. The establishment of small saliva volume detection in mice could be applied in the development of any new therapies for dry mouth.

Expansion of the dentate mossy fiber–CA3 projection in the brain-derived neurotrophic factor-enriched mouse hippocampus

Structural changes that alter hippocampal functional circuitry are implicated in learning impairments, mood disorders and epilepsy. Reorganization of mossy fiber (MF) axons from dentate granule cells is one such form of plasticity. Increased neurotrophin signaling is proposed to underlie MF plasticity, and there is evidence to support a mechanistic role for brain-derived neurotrophic factor (BDNF) in this process. Transgenic mice overexpressing BDNF in the forebrain under the α-calcium/calmodulin-dependent protein kinase II promoter (TgBDNF mice) exhibit spatial learning deficits at 2–3months of age, followed by the emergence of spontaneous seizures at ∼6months. These behavioral changes suggest that chronic increases in BDNF progressively disrupt hippocampal functional organization. To determine if the dentate MF pathway is structurally altered in this strain, the present study employed Timm staining and design-based stereology to compare MF distribution and projection volumes in transgenic and wild-type mice at 2–3months, and at 6–7months. Mice in the latter age group were assessed for seizure vulnerability with a low dose of pilocarpine given 2h before euthanasia. At 2–3months, TgBDNF mice showed moderate expansion of CA3-projecting MFs (∼20%), with increased volumes measured in the suprapyramidal (SP-MF) and intra/infrapyramidal (IIP-MF) compartments. At 6–7months, a subset of transgenic mice exhibited increased seizure susceptibility, along with an increase in IIP-MF volume (∼30%). No evidence of MF sprouting was seen in the inner molecular layer. Additional stereological analyses demonstrated significant increases in molecular layer (ML) volume in TgBDNF mice at both ages, as well as an increase in granule cell number by 8months of age. Collectively, these results indicate that sustained increases in endogenous BDNF modify dentate structural organization over time, and may thereby contribute to the development of pro-epileptic circuitry.

Low Doses of Pilocarpine do not Significantly Increase Outflow Facility in the Cynomolgus Monkey

Low doses (10−9–10−6M) of pilocarpine reportedly increase outflow facility in the organ-cultured human eye, suggesting a direct action on the trabecular meshwork. M3muscarinic receptors have been found in both cultured human trabecular meshwork cells and tissue. We determined whether low pilo doses would increase outflow facility in the living monkey.The anterior chambers of both eyes of 17 pentobarbital anesthetized cynomolgus monkeys were cannulated and outflow facility measured bilaterally by 2-level constant pressure perfusion after an initial 2ml exchange with Bárány's perfusand containing 24.5μM phenylephrine (PE). Two subsequent exchanges were performed with one eye receiving Bárány's+PE+10−10–10−4M pilocarpine and the contralateral eye receiving only Bárány's+PE. Outflow facility was measured for 35–40 min following each exchange. Accommodation and pupil diameter were measured before each exchange and approximately every 10 min during facility measurements.Outflow facility was significantly increased by 154 and 313% in eyes treated with 10−5M and 10−4M pilocarpine, respectively, related to contralateral controls. Accommodation and miosis also were induced only at 10−5M(accommodation, 3.3±1.6 diopters, NS; miosis, −4.1±0.5mm, P⩽0.001) and 10−4M(accommodation, 10.6±0.0 diopters, P⩽0.02; miosis, −3.4±1.0mm, P⩽0.025) pilocarpine.We conclude that low anterior chamber doses of pilocarpine do not increase outflow facility in the living monkey as reported in the organ-cultured human eye, nor do they induce miosis or accommodation. All three parameters respond to pilocarpine at similar doses, and there is no functional evidence of a meaningful outflow facility-relevant pilocarpine effect on the trabecular meshwork at doses lower than those which affect the ciliary muscle.

Dopaminergic regulation of epileptic activity

We evaluated the role of dopamine systems in the propagation of epileptic activity. Focal, limbic seizures were produced by systemically administered pilocarpine (200 mg/kg, i.p.); as previously described this dose produces limbic stereotypes but neither convulsions nor seizure-related brain damage. The systemic pretreatment with D-1, but not D-2, agonists induced convulsions identical to those produced by a higher, convulsant dose of pilocarpine (400 mg/kg). Conversely, the pretreatment with D-1 receptor antagonists prevented the convulsions whereas the D-2 antagonists facilitated the pilocarpine-induced seizures. Furthermore, we studied the effects of intracerebral injections of dopamine agents on seizures induced by pilocarpine. Nigral microinjection of D-1 agonists strongly induced motor seizures in rats treated with the low dose of pilocarpine. On the other hand, microinjection of D-1 antagonists prevented the motor seizures induced by the high dose of pilocarpine. This study indicates that the two dopamine receptor subtypes, D-1 and D-2, exert opposing roles in the control of epilepsy propagation. Substantia nigra pars reticulata appears to be primarily involved in the dopamine-mediated modulation of seizures.

Evidence for a cholinergic role in haloperidol-induced catalepsy.

Experiments in mice tested previous evidence that activation of cholinergic systems promotes catalepsy and that cholinergic mechanisms need to be intact for full expression of neuroleptic-induced catalepsy. Large doses of the cholinomimetic, pilocarpine, could induce catalepsy when peripheral cholinergic receptors were blocked. Low doses of pilocarpine caused a pronounced enhancement of the catalepsy that was induced by the dopaminergic blocker, haloperidol. A muscarinic receptor blocker, atropine, disrupted haloperidol-induced catalepsy. Intracranial injection of an acetylcholine-synthesis inhibitor, hemicholinium, prevented the catalepsy that is usually induced by haloperidol. These findings suggest the hypothesis that the catalepsy that is produced by neuroleptics such as haloperidol is actually mediated by intrinsic central cholinergic systems. Alternatively, activation of central cholinergic systems could promote catalepsy by suppression of dopaminergic systems.