Comparative Review of Effects of Pien Tze Huang and AnGong NiuHuang Pill and their Potential on Treatment of Central Nervous System Diseases.

The ancient composite formulae Angong Niuhuang pill and Pien Tze Huang, which were used a few hundred years ago to treat febrile disease and inflammation, respectively, are found to exert effects benefiting other neurological diseases and conditions. This short review introduces the main constituents of the two formulae, looking into both the cumulative synergetic and possible individual effects of each herb or animal apcoien. In essence, the main effects of Angong Niuhuang pill include anti-inflammation, antioxidation, anti-cell death, anticonvulsion, antiedema, antipyretic, antithrombotic, antimicrobial (bacteria, viruses, fungi), neuroprotective effects, and cardiovascular protection. The main effects of Pien Tze Huang include anti-inflammation, antioxidation, anti-cell death, antithrombotic, antimicrobial, neuroprotective effects, and cardiovascular protection. Comparing both composites, similarities in the effects and part of the components are found, showing some pharmacological evidence. This review casts light on research on the effects of neuroprotective and cardiovascular protective mechanisms as well as treatment mechanisms for cerebral accidents from the integrative medicine perspective.

Reaction of the Liver upon Long-Term Treatment of Fluoxetine and Atorvastatin Compared with Alcohol in a Mouse Model.

BACKGROUND: Alcoholism is known to cause liver toxicity and is extensively researched. On the other hand, stress, depression, and obesity are interrelated conditions with alcoholism, and their medications would affect the liver itself. In this study, we investigated the effects of the drugs fluoxetine and atorvastatin on the liver and compared with those of alcohol in a mouse model. METHODS: Comparisons of animals treated with the three drugs were carried out: serum aspartate transaminase (AST), alanine transaminase (ALT), and albumin were measured; liver tumor necrosis factor alpha (TNF alpha) and transforming growth factor beta (TGF beta-1) levels were evaluated; proliferative cells were detected via immunohistochemistry (IHC) targeting on proliferating cell nuclear antigen (PCNA) and minichromosome maintenance complex component 2 (MCM2); for apoptosis, IHC targeting on activated caspase-3 and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) were employed; and histopathology was also documented in all groups. RESULTS: For ALT, AST, albumin, and liver TNF alpha, only the ethanol group surged to significantly higher levels. For TGF beta-1, both ethanol and atorvastatin groups reached a significantly higher level. PCNA and MCM2 showed increased proliferation in the livers of all three groups, with the ethanol group having the highest number of positive cells followed by atorvastatin and then the fluoxetine group. As for cell death, both ethanol and fluoxetine groups showed significantly more apoptosis than control in TUNEL and activated caspase-3, while in the atorvastatin group, activated caspase-3 positive cells increased significantly, but the increase in TUNEL-positive cells did not reach statistical significance.

Chronic sub-anesthetic ketamine induces permanent hypolocomotion and impairment of hippocampus in adolescent cynomolgus monkeys.

Ketamine has gained increasing popularity in adolescent drug abusers worldwide. However, relatively little is known about the long-term effects of recreational ketamine on adolescent hippocampus. The present study investigates the effects of different periods (1, 3 and 6 months) of recreational ketamine administration on locomotor activity and neuron damage in the hippocampus of adolescent cynomolgus monkeys. 32 4-year-old male cynomolgus monkeys were divided into control, 1-month, 3-month and 6-month groups. All animals in ketamine groups received daily intravenous injection with 1 mg/kg ketamine in saline for respective 1, 3 or 6 months while control group received normal saline. Automatic behaviors were recorded for 10 min before and after ketamine and saline administration. Meanwhile, the markers of apoptosis in the hippocampus were assessed using terminal deoxynucleotidyl transferase-mediated biotinylated dUTP nick end labeling (TUNEL), electron microscopy and western blotting. Results showed that ketamine significantly decreased locomotor activity, increased apoptotic neurons and pro-apoptotic proteins, cleaved Caspase-3 and Bax, while decreased the anti-apoptotic protein Bcl-2 in the hippocampus after 6-month ketamine administration. Our study suggested that chronically recreational ketamine might induce hypolocomotion and neurotoxic effect via apoptotic pathway in adolescent hippocampus of monkeys.

Effects of Perinatal Exposure to Ketamine on the Developing Brain.

Initially used as an analgesic and anesthetic, ketamine has unfortunately been abused as a popular recreational party drug due to its psychotropic effects. Over the last decade, ketamine has also emerged as an effective rapid-onset anti-depressant. The increasingly widespread use and misuse of the drug in infants and pregnant women has posed a concern about the neurotoxicity of ketamine to the immature brains of developing fetuses and children. In this review, we summarize recent research findings on major possible mechanisms of perinatal ketamine-induced neurotoxicity. We also briefly summarize the neuroprotective effects of ketamine in the presence of noxious stimuli. Future actions include implementation of more drug abuse education and prevention campaigns to raise the public's awareness of the harmful effects of ketamine abuse; further investigations to justify the clinical use of ketamine as analgesic, anesthetic and anti-depressant; and further studies to develop alternatives to ketamine or treatments that can alleviate the detrimental effects of ketamine use, especially in infants and pregnant women.

Gastric myoelectric activity during cisplatin-induced acute and delayed emesis reveals a temporal impairment of slow waves in ferrets: effects not reversed by the GLP-1 receptor antagonist, exendin (9-39).

Preclinical studies show that the glucagon-like peptide-1 (GLP-1) receptor antagonist, exendin (9-39), can reduce acute emesis induced by cisplatin. In the present study, we investigate the effect of exendin (9-39) (100 nmol/24 h, i.c.v), on cisplatin (5 mg/kg, i.p.)-induced acute and delayed emesis and changes indicative of 'nausea' in ferrets. Cisplatin induced 37.2 ± 2.3 and 59.0 ± 7.7 retches + vomits during the 0-24 (acute) and 24-72 h (delayed) periods, respectively. Cisplatin also increased (P<0.05) the dominant frequency of gastric myoelectric activity from 9.4 ± 0.1 to 10.4 ± 0.41 cpm and decreased the dominant power (DP) during acute emesis; there was a reduction in the % power of normogastria and an increase in the % power of tachygastria; food and water intake was reduced. DP decreased further during delayed emesis, where normogastria predominated. Advanced multifractal detrended fluctuation analysis revealed that the slow wave signal shape became more simplistic during delayed emesis. Cisplatin did not affect blood pressure (BP), but transiently increased heart rate, and decreased heart rate variability (HRV) during acute emesis; HRV spectral analysis indicated a shift to 'sympathetic dominance'. A hyperthermic response was seen during acute emesis, but hypothermia occurred during delayed emesis and there was also a decrease in HR. Exendin (9-39) did not improve feeding and drinking but reduced cisplatin-induced acute emesis by ~59 % (P<0.05) and antagonised the hypothermic response (P<0.05); systolic, diastolic and mean arterial BP increased during the delayed phase. In conclusion, blocking GLP-1 receptors in the brain reduces cisplatin-induced acute but not delayed emesis. Restoring power and structure to slow waves may represent a novel approach to treat the side effects of chemotherapy.

Chronic Ketamine Exposure Causes White Matter Microstructural Abnormalities in Adolescent Cynomolgus Monkeys.

Acute and repeated exposures to ketamine mimic aspects of positive, negative, and cognitive symptoms of schizophrenia in humans. Recent studies by our group and others have shown that chronicity of ketamine use may be a key element for establishing a more valid model of cognitive symptoms of schizophrenia. However, current understanding on the long-term consequences of ketamine exposure on brain circuits has remained incomplete, particularly with regard to microstructural changes of white matter tracts that underpin the neuropathology of schizophrenia. Thus, the present study aimed to expand on previous investigations by examining causal effects of repeated ketamine exposure on white matter integrity in a non-human primate model. Ketamine or saline (control) was administered intravenously for 3 months to male adolescent cynomolgus monkeys (n = 5/group). Diffusion tensor imaging (DTI) experiments were performed and tract-based spatial statistics (TBSS) was used for data analysis. Fractional anisotropy (FA) was quantified across the whole brain. Profoundly reduced FA on the right side of sagittal striatum, posterior thalamic radiation (PTR), retrolenticular limb of the internal capsule (RLIC) and superior longitudinal fasciculus (SLF), and on the left side of PTR, middle temporal gyrus and inferior frontal gyrus were observed in the ketamine group compared to controls. Diminished white matter integrity found in either fronto-thalamo-temporal or striato-thalamic connections with tracts including the SLF, PTR, and RLIC lends support to similar findings from DTI studies on schizophrenia in humans. This study suggests that chronic ketamine exposure is a useful pharmacological paradigm that might provide translational insights into the pathophysiology and treatment of schizophrenia.

How Ketamine Affects Livers of Pregnant Mice and Developing Mice?

It is well known that ketamine abuse can induce liver damage in adult addicts, but the effects of ketamine abuse in pregnant mothers on their offspring have received less attention. In this study, we investigated the effects of 5-day ketamine injections (30 mg/kg) to pregnant Institute for Cancer Research (ICR) mice during early gestation or mid-gestation on the aspartate aminotransferase (AST) and alkaline phosphatase (ALP) activities of the mothers and the offspring. We also looked into whether administering ketamine treatment to the mothers had any effects on the extent of fibrosis, cell proliferation and cell death in the livers of the newborns. No significant biochemical differences were found between treatment and control groups in the mothers. In the offspring, ketamine treatment mildly suppressed the gradual increase of hepatic AST activity in neonates during liver maturation. Measurements of hepatic ALP activity and lactic acid dehydrogenase (LDH) immunoreactivity revealed that ketamine treatment may lead to increased cell death. Proliferation of liver cells of the newborns was also retarded as shown by reduced proliferative cell nuclear antigen (PCNA) immunoreactivity in the ketamine groups. No obvious fibrosis was evident. Thus, we demonstrated that ketamine administration to pregnant mice suppressed hepatic development and also induced liver cell death of the offspring.

Centrally located GLP-1 receptors modulate gastric slow waves and cardiovascular function in ferrets consistent with the induction of nausea.

Glucagon-like peptide-1 (GLP-1) receptor agonists are indicated for the treatment of Type 2 diabetes and obesity, but can cause nausea and emesis in some patients. GLP-1 receptors are distributed widely in the brain, where they contribute to mechanisms of emesis, reduced appetite and aversion, but it is not known if these centrally located receptors also contribute to a modulation of gastric slow wave activity, which is linked causally to nausea. Our aim was to investigate the potential of the GLP-1 receptor agonist, exendin-4, administered into the 3rd ventricle to modulate emesis, feeding and gastric slow wave activity. Thermoregulation and cardiovascular parameters were also monitored, as they are disturbed during nausea. Ferrets were used as common laboratory rodents do not have an emetic reflex. A guide cannula was implanted into the 3rd ventricle for delivering a previously established dose of exendin-4 (10nmol), which had been shown to induce emesis and behaviours indicative of 'nausea'. Radiotelemetry recorded gastric myoelectric activity (GMA; slow waves), blood pressure and heart rate variability (HRV), and core temperature; food intake and behaviour were also assessed. Exendin-4 (10nmol, i.c.v.) decreased the dominant frequency of GMA, with an associated increase in the percentage of bradygastric power (lasting ~4h). Food intake was inhibited in all animals, with 63% exhibiting emesis. Exendin-4 also increased blood pressure (lasting ~24h) and heart rate (lasting ~7h), decreased HRV (lasting ~24h), and caused transient hyperthermia. None of the above parameters were emesis-dependent. The present study shows for the first time that gastric slow waves may be modulated by GLP-1 receptors in the brain through mechanisms that appear independent from emesis. Taken together with a reduction in HRV, the findings are consistent with changes associated with the occurrence of nausea in humans.

New elements in the interreceptor matrix: a comparative study of Megavilli and Landolt's club.

Megavilli and Landolt's clubs were reported in the interreceptor matrix of the retina of the goldfish and neonatal rat for the first time. Megavilli encroach onto the inner or outer segments of photoreceptors and were different from microvilli. Landolt's clubs were not present in the adult rat but only in the adult goldfish.

Visual Sexual Stimulation and Erection, a Brief Review with New fMRI Data.

This review examines brain sites involved in sexual stimulation. New data on brain activation sites in individuals having erections concomitant with visual erotic stimulation were documented. The activation was chiefly at the midbrain around the cerebral peduncle, and in the pons centering on the tegmentum, they are indicated by blood oxygenation level dependent (BOLD) images captured by functional magnetic resonance imaging (fMRI). The cerebellum and inferior temporal lobe were activated more extensively in individuals viewing pornographic movie with a concomitant erection than those without. Similarly, individuals with erection had activations in the midbrain and pons, while drug addicts had neither erections nor any of these brainstem active sites. From our observation in the new data, we deduced three possible transmitters might be involved in erection: i) cholinergic neurons forming descending pathways and associated with motor activity ii) gamma-aminobutyric acid (GABA), directly or indirectly via decreasing pathways, modulating autonomic vascular responses in the penile vasculature causing the filling of blood iii) GABA decreases to stimulate dopamine increase in ventral tegmentum of the brain, leading to euphoric responses.

Ketamine Self-Administration Reduces the Homeostasis of the Glutamate Synapse in the Rat Brain.

Ketamine is a non-competitive antagonist of the NMDA glutamate receptor with psychotomimetic and reinforcing properties, although recent work has pointed out its antidepressant action following acute exposure. Our aim was to investigate the expression of crucial components of the glutamate synapse following chronic ketamine self-administration (S/A), focusing our attention on medial prefrontal cortex (mPFC) and hippocampus (Hip), two brain regions involved in compulsive drug-seeking and drug-related cognitive disorders. Rats self-administered ketamine at a sub-anesthetic dose for 5-6 weeks and were sacrificed 24 h after the last drug exposure. We found a general downregulation of glutamate receptor expression that was brain region-dependent. In fact, in the mPFC, we found reduced expression of NMDA receptor subunits, whereas AMPA receptor protein levels were reduced in Hip; of note, specific scaffolding proteins of NMDA and AMPA receptors were also reduced in mPFC and Hip, respectively. Moreover, the metabotropic mGluR5 receptor was similarly downregulated in these brain regions. These findings reveal a dynamic impairment of glutamate homeostasis in the mPFC and Hip that may represent a signature of long-term exposure to ketamine S/A. Further, this decrement, similarly observed in humans and animal models of schizophrenia may represent a specific feature of the human disease endophenotype.

A Review of Three Commonly Used Herbs Which Enhance Memory and New Evidences Which Show Their Combination Could Improve Memory in Young Animals.

BACKGROUND: This review looks into the herbs Gingko biloba, Polygala tenuifolia, and Lycii fructus for their widely studied neuroprotective properties. In particular, we investigated memory enhancing effect of these herbs, and their potential synergetic effect on memory with new data. Sixmonth treated mice demonstrated shorter escape latency in water maze and shorter arrival time in a consolidated memory task. Immunochemistry showed evident increase in superoxide dismutase activities in the prefrontal cortex, implying protection against free radicals during aging. Discrete increase of catecholaminergic neurons was found in the prefrontal cortex, hippocampus, corpus striatum, and midbrain, suggesting better memory and better control on mood and behavior. Necrotic cells in the brain decreased as indicated by immunocytochemistry of lactic dehydrogenase. Terminal deoxynucleotidyl transferase dUTP nick end labeling showed no apoptotic cells in most brain areas in high dose group. Biochemistry revealed increase of dopaminergic cells in treatment groups at prefrontal cortex, and in the hippocampus and cerebellum of the high dose group. Most 6-month groups showed increase of serotonin in all three areas. For the high dose group, GABA increased in the hippocampus but not prefrontal cortex, which would help induce sleep at night. Protein kinase C increased in most groups at prefrontal cortex, hippocampus and cerebellum, signifying increase of possible signal transduction pathways for memory or other nervous activations. CONCLUSION: Our results intimate that the interaction of the three herbs exerts beneficial effects on memory, associated cognitive function, and necrosis. Future investigations based on the present data shall aid development of clinically relevant medication.

Insights into the central pathways involved in the emetic and behavioural responses to exendin-4 in the ferret.

BACKGROUND: GLP-1 receptor agonists are utilised for the treatment of Type-2 diabetes but can be associated with undesirable effects of nausea and vomiting. OBJECTIVES: To investigate the role of GLP-1 receptors in mechanisms of emesis, behaviours indicative of nausea (BIN) and food intake in the ferret. RESULTS: Exendin-4 (10 and 30nmol, i.c.v.) induced emesis, inhibited food intake, and increased the frequency of BIN. Increases in c-Fos in the brainstem, midbrain and forebrain occurred in animals exhibiting emesis; no activation of the brainstem occurred in animals not vomiting. Exendin-4 (10nmol, i.c.v.) when preceded by i.c.v. saline (15µl), was not emetic but induced BIN and inhibited food intake; exendin (9-39) (100nmol) reduced BIN only. c-Fos showed that consistent with the absence of emesis in saline/exendin-4 treated animals there was no increase in c-Fos in the brainstem, but it increased in midbrain and forebrain nuclei. Excepting the amygdala, exendin (9-39) was without efffect on the increases in c-Fos. Analysis of c-Fos data showed a positive linear relationship between midbrain and forebrain areas irrespective of the occurrence of emesis induced by exendin-4. In contrast, brainstem and midbrain c-Fos levels were positively correlated, but only in animals with emesis. CONCLUSIONS: The brainstem is critical for exendin-4-induced emesis but suppression of food intake and BIN involves more rostral brain sites. Exendin-4-induced BIN and c-Fos activation of the amygdala are sensitive to exendin (9-39), whereas the suppression of food intake is not implicating separate control mechanisms for emesis and BIN.

Bilateral Common Carotid Artery Occlusion in Spontaneously Hypertensive Rats: A Feasible Animal Model for Ocular Ischemic Syndrome.

The purpose of this study was to investigate the feasibility of inducing ocular ischemic syndrome in spontaneously hypertensive rats. Hypertensive and normotensive Wistar-Kyoto rats had bilateral occlusion or sham surgery. They were divided into 4 groups: (1) hypertensive-ischemia, (2) hypertensive-sham, (3) normotensive-ischemia, and (4) normotensive-sham. Four months after the operation, the global changes of the eye and pupillary light reflex were assessed. Then each rat was perfused, and randomly one of the bulbuses oculi was prepared as retinal flat mounts for investigation of vascular changes. The opposite eyeball was prepared as a paraffin section for observation of the linear density of retinal ganglion cells and for thickness measurement. One hypertensive-ischemia rat had a cataract in one eye and another rat in the same group had bulbus oculi collapse in one eye. The light reflex disappeared in 13.33% of hypertensive-ischemia rats, and the rest of the hypertensive-ischemia rats and normotensive-ischemia rats had slow reflex. Compared with the respective controls, the peripheral retinal vascular network in hypertensive-ischemia and normotensive-ischemia rats was sparse; linear density of the retinal ganglion cells was significantly reduced; and the retinal thickness was reduced. Compared with normotensive-ischemia rats, the hypertensive-ischemia rats demonstrated more severe changes. After bilateral common carotic artery occlusion, the eyes of hypertensive rats developed various pathological changes similar to those of ocular ischemic syndrome. In conclusion, an animal model for ocular ischemic syndrome can be created by bilateral common carotid artery occlusion in spontaneously hypertensive rats. Anat Rec, 299:806-814, 2016. © 2016 Wiley Periodicals, Inc.

The modulation of BDNF expression and signalling dissects the antidepressant from the reinforcing properties of ketamine: Effects of single infusion vs. chronic self-administration in rats.

Ketamine is a drug of abuse with a unique profile, which besides its inherent mechanism of action as a non-competitive antagonist of the NMDA glutamate receptor, displays both antidepressant and reinforcing properties. The major aim of our study was to find a molecular signature of ketamine that may help in discriminating between its reinforcing and antidepressant effects. To this end, we focused our attention on BDNF, a neurotrophin that has been shown to play a role in both antidepressant and reinforcing properties of several drugs. Rats were exposed to self-administer intravenous (IV) ketamine (S/A) for 43 days or to receive a single IV ketamine 0.5mg/kg, or vehicle infusion. Although the dose we employed is lower than that reported by the literature, it however yields Cmax values that correspond to those achieved in humans after antidepressant treatment. Our results show that while the single infusion of ketamine increased the neurotrophin expression in the hippocampus while reducing it in the ventral striatum, a feature shared with other antidepressants, the repeated self-administration reduced mBDNF expression and its downstream signalling in both ventral striatum and hippocampus. Further, we here show that phosphorylation of Akt is oppositely regulated by ketamine, pointing to this pathway as central to the different actions of the drug. Taken together, we here point to BDNF and its downstream signalling pathway as a finely tuned mechanism whose modulation might subserve the different features of ketamine.

Short-Term Flavoxate Treatment Alters Detrusor Contractility Characteristics: Renewed Interest in Clinical Use?

OBJECTIVES: Flavoxate has had a long history of use in the treatment of overactive bladder, despite the lack of documentation on its clinical efficacy and mechanism(s) of action. This study was conducted to understand how contractility characteristics of the detrusor are affected after a short period of flavoxate treatment. METHODS: Eight-week-old mice were treated with flavoxate for 5 days and detrusor contractile responses were examined ex vivo under different pharmacological and electrical stimuli. RESULTS: K(+) -Krebs'-induced contraction developed more slowly while 64 Hz electrical field stimulation-induced contraction developed faster in flavoxate-treated strips when compared to control. Amplitudes of maximal and steady-state contraction induced by 3 µmol/L carbachol were also larger after flavoxate treatment. Control strips showed an overall greater dependence on stimulus strength in eliciting the responses. CONCLUSIONS: These findings provided new information of how short-term flavoxate treatment altered contractility characteristics at the bladder level, which may instill new interest in investigating the use of this drug in bladder disorders not responding well to conventional treatments.

Antifungal mode of action of macrocarpal C extracted from Eucalyptus globulus Labill (Lan An) towards the dermatophyte Trichophyton mentagrophytes.

BACKGROUND: The fresh leaves of Eucalyptus globulus Labill. (Lan An) have been used in Chinese medicine for many years to treat dermatomycosis. Macrocarpal C was isolated from this herb and identified as its major antifungal component by bioassay-guided purification. This study aims to investigate the antifungal activity of macrocarpal C against Trichophyton mentagrophytes, which can cause tinea pedis. METHODS: Fresh leaves of E. globulus were extracted with 95 % ethanol, and the resulting ethanolic extracts were dried before being partitioned with n-hexane. The n-hexane layer was then subjected to chromatographic purification to give macrocarpal C. The antifungal minimum inhibitory concentration (MIC) of macrocarpal C was determined using the standard M38-A2 method described by the Clinical Laboratory Standards Institute (CLSI). The mode of action of macrocarpal C was elucidated using three in vitro assays, including (1) a fungal membrane permeability test using SYTOX(®) Green; (2) a reactive oxygen species (ROS) production test using 5-(and-6)-carboxy-2',7'-dihydrodichlorofluorescein diacetate as a cell-permeable fluorogenic probe; and (3) a DNA fragmentation test based on terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) detection. Terbinafine hydrochloride and nystatin were used as positive controls. RESULTS: The suppression in the growth of T. mentagrophytes following its treatment with macrocarpal C was associated with an increase in the permeability of the fungal membrane (P = 0.0043 when compared to control); an increase in the production of intracellular ROS (P = 0.0063); and the induction of apoptosis as a consequence of DNA fragmentation (P = 0.0007). CONCLUSION: This study demonstrated that the antifungal action of macrocarpal C was associated with increases of membrane permeability, intracellular ROS and DNA fragmentation.

Platelet mitochondrial dysfunction of DM rats and DM patients.

It is known that cardiovascular complications plays important roles in the development of diabetes mellitus (DM) and platelet dysfunction is one of the key reasons which led to microangiopathy. This study was designed to investigate the mitochondria function changes of platelet in DM rats and DM patients. The results showed that the platelets viability, platelet adenosine triphosphate (ATP) content and platelet mitochondrial ATP content of DM rats were lower than that of normal rats; when incubated in vitro for 24 h, platelet number and mitochondrial membrane potential (MMP) of DM rats were lower than that of normal rats, reactive oxygen species (ROS) was higher than that of normal rats. For DM patients, their platelet number and ROS were higher and MMP was lower than those of normal people; when incubated in vitro for 24 h, platelet viability of DM patients was lower than that of normal people. Platelet ultra-microstructures of DM rats and DM patients were abnormal. These results suggested that platelet mitochondrial function of both DM rats and DM patients was impaired when compared to normal rats and normal people, respectively. Platelets may be applied as a biomarker to observe the mitochondrial changes during DM.

Propidium iodide (PI) stains Nissl bodies and may serve as a quick marker for total neuronal cell count.

Propidium iodide (PI) reacts with both DNA and RNA and is a commonly used fluorescent reagent for nucleic acid staining. The aim of the study was to compare the cellular staining patterns of PI with that of Nissl staining in rat nervous tissues and to report a modified staining method that selectively labels Nissl bodies in neurons. Cryosections and paraffin sections of different tissues of normal Sprague-Dawley rats, including trigeminal ganglia, dorsal root ganglia, spinal cord, liver, and small intestine, were stained by either PI or the hematoxylin and eosin method. Some sections were treated with RNase or DNase before the above staining, and some were double stained with PI and a Nissl stain. The sections were observed by light, fluorescence or confocal microscopy. Results showed strong PI signals detected as patterns of granules in the neuronal cytoplasm of all nervous tissues, whereas the staining of neuronal nuclei was weaker. In contrast, nuclei of neuroglial cells were strongly stained by PI, while the cytoplasm was not obviously stained. Pretreatment of the neural tissue with RNase abolished the PI signals. Furthermore, the PI positive granules in neuronal cytoplasm co-localized with Nissl bodies stained by the fluorescent Nissl stain. When the tissue was pretreated with DNase, PI only stained the cytoplasmic granules of neurons, but not that of glial cells. Our results show that PI stains Nissl bodies and may serve as an economical and convenient neuron marker for neuronal cell counting when specific neural markers such as antibodies are not readily available.

Differential hypoglycaemic, anorectic, autonomic and emetic effects of the glucagon-like peptide receptor agonist, exendin-4, in the conscious telemetered ferret.

BACKGROUND: Rodents are incapable of emesis and consequently the emetic potential of glucagon-like peptide-1 receptor (GLP-1R) agonists in studies designed to assess a potential blood glucose lowering action of the compound was missed. Therefore, we investigated if the ferret, a carnivore with demonstrated translation capability in emesis research, would identify the emetic potential of the GLP-1R agonist, exendin-4, and any associated effects on gastric motor function, appetite and cardiovascular homeostasis. METHODS: The biological activity of the GLP-1R ligands was investigated in vivo using a glucose tolerance test in pentobarbitone-anesthetised ferrets and in vitro using organ bath studies. Radiotelemetry was used to investigate the effect of exendin-4 on gastric myoelectric activity (GMA) and cardiovascular function in conscious ferrets; behaviour was also simultaneously assessed. Western blot was used to characterize GLP-1R distribution in the gastrointestinal and brain tissues. RESULTS: In anesthetised ferrets, exendin-4 (30 nmol/kg, s.c.) reduced experimentally elevated blood glucose levels by 36.3%, whereas the GLP-1R antagonist, exendin (9-39) (300 nmol/kg, s.c.) antagonised the effect and increased AUC0-120 by 31.0% when injected alone (P < 0.05). In animals with radiotelemetry devices, exendin-4 (100 nmol/kg, s.c.) induced emesis in 1/9 ferrets, but inhibited food intake and decreased heart rate variability (HRV) in all animals (P < 0.05). In the animals not exhibiting emesis, there was no effect on GMA, mean arterial blood pressure, heart rate, or core body temperature. In the ferret exhibiting emesis, there was a shift in the GMA towards bradygastria with a decrease in power, and a concomitant decrease in HRV. Western blot revealed GLP-1R throughout the gastrointestinal tract but exendin-4 (up to 300 nM) and exendin (9-39), failed to contract or relax isolated ferret gut tissues. GLP-1R were found in all major brain regions and the levels were comparable those in the vagus nerve. CONCLUSIONS: Peripherally administered exendin-4 reduced blood glucose and inhibited feeding with a low emetic potential similar to that in humans (11% vs 12.8%). A disrupted GMA only occurred in the animal exhibiting emesis raising the possibility that disruption of the GMA may influence the probability of emesis occurring in response to treatment with GLP-1R agonists.