Dysregulation of epithelial ion transport and neurochemical changes in the colon of a parkinsonian primate.

The pathological changes underlying gastrointestinal (GI) dysfunction in Parkinson's disease (PD) are poorly understood and the symptoms remain inadequately treated. In this study we compared the functional and neurochemical changes in the enteric nervous system in the colon of adult, L-DOPA-responsive, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated common marmoset, with naïve controls. Measurement of mucosal vectorial ion transport, spontaneous longitudinal smooth muscle activity and immunohistochemical assessment of intrinsic innervation were each performed in discrete colonic regions of naïve and MPTP-treated marmosets. The basal short circuit current (Isc) was lower in MPTP-treated colonic mucosa while mucosal resistance was unchanged. There was no difference in basal cholinergic tone, however, there was an increased excitatory cholinergic response in MPTP-treated tissues when NOS was blocked with L-Nω-nitroarginine. The amplitude and frequency of spontaneous contractions in longitudinal smooth muscle as well as carbachol-evoked post-junctional contractile responses were unaltered, despite a decrease in choline acetyltransferase and an increase in the vasoactive intestinal polypeptide neuron numbers per ganglion in the proximal colon. There was a low-level inflammation in the proximal but not the distal colon accompanied by a change in α-synuclein immunoreactivity. This study suggests that MPTP treatment produces long-term alterations in colonic mucosal function associated with amplified muscarinic mucosal activity but decreased cholinergic innervation in myenteric plexi and increased nitrergic enteric neurotransmission. This suggests that long-term changes in either central or peripheral dopaminergic neurotransmission may lead to adaptive changes in colonic function resulting in alterations in ion transport across mucosal epithelia that may result in GI dysfunction in PD.

Contractile dysfunction and nitrergic dysregulation in small intestine of a primate model of Parkinson's disease.

Bowel dysfunction is a common non-motor symptom in Parkinson's disease (PD). The main contractile neurotransmitter in the GI tract is acetylcholine (ACh), while nitric oxide (NO) causes the relaxation of smooth muscle in addition to modulating ACh release. The aim of this study was to characterise functional and neurochemical changes in the isolated ileum of the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated marmoset, an established model of PD motor dysfunction. While NO-synthase inhibitor L-NAME concentration dependently augmented the neurogenically-evoked contractions and inhibited the relaxations in normal tissues, it had no effects on the MPTP ileum. Immunohistochemical analyses of the myenteric plexus showed that ChAT-immunoreactivity (-ir) was significantly reduced and the density of the enteric glial cells as shown by SOX-10-ir was increased. However, no change in TH-, 5-HT-, VIP- or nNOS-ir was observed in the MPTP tissues. The enhancement of the neurogenically-evoked contractions and the inhibition of the relaxation phase by L-NAME in the control tissues is in line with NO's direct relaxing effect on smooth muscle and its indirect inhibitory effect on ACh release. The absence of the relaxation and the inefficacy of L-NAME in the MPTP tissues suggests that central dopaminergic loss dopamine may eventually lead to the impairment of NO signal coupling that affects bowel function, and this may be the result of a complex dysregulation at the level of the neuroeffector junction.

Altered detrusor contractility in MPTP-treated common marmosets with bladder hyperreflexia.

Bladder hyperreflexia is a common non-motor feature of Parkinson's disease. We now report on the contractility of the isolated primate detrusor strips devoid of nerve input and show that following MPTP, the amplitude and frequency of spontaneous contraction was increased. These responses were unaffected by dopamine D1 and D2 receptor agonists A77636 and ropinirole respectively. Contractions by exogenous carbachol, histamine or ATP were similar and no differences in the magnitude of noradrenaline-induced relaxation were seen in detrusor strip obtained from normal and MPTP-treated common marmosets (Callithrix jacchus). However, the neurogenic contractions following electrical field stimulation of the intrinsic nerves (EFS) were markedly greater in strips obtained from MPTP treated animals. EFS evoked non-cholinergic contractions following atropine were also greater but the contribution of the cholinergic innervation as a proportion of the overall contraction was smaller in the detrusor strips of MPTP treated animals, suggesting a preferential enhancement of the non-cholinergic transmission. Although dopaminergic mechanism has been proposed to underlie bladder hyperreflexia in MPTP-treated animals with intact bladder, the present data indicates that the increased neurogenically mediated contractions where no extrinsic innervation exists might be due to long-term adaptive changes locally as a result of the loss of the nigrostriatal output.

Successful treatment of facial papules with electrodessication in a patient with Birt-Hogg-Dubé syndrome.

We report a case of a 51-year-old Hispanic female who presented with a several year history of multiple flesh colored papules of cosmetic concern on the nose and medial cheeks. Biopsies revealed fibrofolliculoma and trichodiscoma. The patient was referred for genetic testing and was found to be positive for the FLCN gene defect, confirming a diagnosis of Birt-Hogg-Dubé syndrome. Further work-up with screening renal ultrasound and CT scan of the thorax and abdomen was unrevealing. For treatment of these skin lesions, dermasanding was attempted initially with only minimal benefit. She subsequently had multiple lesions treated with electrodessication at a low setting and was very pleased with the results. Curettage was not performed and importantly, there has yet to be a recurrence of lesions treated with only hyfrecation.

A novel series of benzimidazole NR2B-selective NMDA receptor antagonists.

A series of novel benzimidazoles are discussed as NR2B-selective N-methyl-d-aspartate (NMDA) receptor antagonists. High throughput screening (HTS) efforts identified a number of potent and selective NR2B antagonists such as 1. Exploration of the substituents around the core of this template identified a number of compounds with high potency for NR2B (pIC(50) >7) and good selectivity against the NR2A subunit (pIC(50) <4.3) as defined by FLIPR-Ca(2+) and radioligand binding studies. These agents offer potential for the development of therapeutics for a range of nervous system disorders including chronic pain, neurodegeneration, migraine and major depression.

Contact and fumigant toxicity of a botanical-based feeding deterrent of the stable fly, Stomoxys calcitrans (Diptera: Muscidae).

The stable fly, Stomoxys calcitrans (L.), has been considered one of the most serious biting flies of confined and pastured livestock. The economic losses caused by the stable fly to the cattle industry in the United States exceed $2 billion annually. Current practices for managing stable flies using insecticides provide only marginal control. Insecticide resistance has also been recently reported in stable flies. The present study reports the use of plant-based insecticides, for example, essential oils, as alternatives for managing this fly pest. The toxicity of several plant essential oils and selected ingredient compounds was evaluated by contact and fumigant toxicity bioassays. Catnip oil (20 mg dosage) showed the highest toxicity against stable flies, the shortest knock-down time (∼7 min), and the quickest lethal time (∼19 min). Toxicity levels similar to catnip oil were found among three insect repellent compounds (N,N-diethyl-3-methylbenzamide, 2-methylpiperidinyl-3-cyclohexene-1-carboxamide, (1S,2'S)-2-methylpiperidinyl-3-cyclohexene-1-carboxamide). No differences in knock-down and lethal times were found among the catnip oil and its two active ingredient compounds. Similar stable fly mortality was observed using a 20 mg dose of catnip oil in a modified K&D system and a fumigant jar. When catnip oil was topically applied to stable flies, the least lethal dose was 12.5 µg/fly, and a 50 µg/fly dose resulted in 100% mortality. The blood-feeding behavior of stable flies was also negatively affected by the topical application of catnip oil, and the effect was dose-dependent. This study demonstrated that catnip oil has both contact and fumigant toxicity against the stable fly and thus has the potential as an alternative for stable fly control.

GW627368X ((N-{2-[4-(4,9-diethoxy-1-oxo-1,3-dihydro-2H-benzo[f]isoindol-2-yl)phenyl]acetyl} benzene sulphonamide): a novel, potent and selective prostanoid EP4 receptor antagonist.

1. N-{2-[4-(4,9-diethoxy-1-oxo-1,3-dihydro-2H-benzo[f]isoindol-2-yl)phenyl]acetyl}benzene sulphonamide (GW627368X) is a novel, potent and selective competitive antagonist of prostanoid EP4 receptors with additional human TP receptor affinity. 2. At recombinant human prostanoid EP4 receptors expressed in HEK293 cells, GW627368X produced parallel rightward shifts of PGE2 concentration-effect (E/[A]) curves resulting in an affinity (pKb) estimate of 7.9 +/- 0.4 and a Schild slpoe not significantly different from unity. The affinity was independent of the agonist used. 4. In rings of phenylephrine precontracted piglet saphenous vein, GW627368X (30-300 nM) produced parallel rightward displacement of PGE2 E/[A] curves (pKb = 9.2 +/- 0.2; slope = 1). 4. GW627368X appears to bind to human prostanoid TP receptors but not the TP receptors of other species. In human washed platelets, GW627368X (10 microM) produced 100% inhibition of U-46619 (EC100)-induced aggregation (approximate pA2 approximately 7.0). However, in rings of rabbit and piglet saphenous vein and of guinea-pig aorta GW627368X (10 microM) did not displace U-46619 E/[A] curves indicating an affinity of < 5.0 for rabbit and guinea-pig prostanoid TP receptors. 5. In functional assays GW627368X is devoid of both agonism and antagonist affinity for prostanoid CRTH2, EP2, EP3, IP and FP receptors. At prostanoid EP1 receptors, GW627368X was an antagonist with a pA2 of 6.0, and at prostanoid IP receptors the compound increased the maximum effect of iloprost by 55%. At rabbit prostanoid EP2 receptors the pA2 of GW627368X was < 5.0. 6. In competition radioligand bioassays, GW627368X had affinity for human prostanoid EP4 and TP receptors (pKi = 7.0 +/- 0.2 (n = 10) and 6.8 (n = 2), respectively). Affinity for all other human prostanoid receptors was < 5.3. 7. GW627368X will be a valuable tool to explore the role of the prostanoid EP4 receptor in many physiological and pathological settings.