Azithromycin reduces hemoglobin-induced innate neuroimmune activation

Neonatal intraventricular hemorrhage (IVH) releases blood products into the lateral ventricles and brain parenchyma. There are currently no medical treatments for IVH and surgery is used to treat a delayed effect of IVH, post-hemorrhagic hydrocephalus. However, surgery is not a cure for intrinsic brain injury from IVH, and is performed in a subacute time frame. Like many neurological diseases and injuries, innate immune activation is implicated in the pathogenesis of IVH. Innate immune activation is a pharmaceutically targetable mechanism to reduce brain injury and post-hemorrhagic hydrocephalus after IVH. Here, we tested the macrolide antibiotic azithromycin, which has immunomodulatory properties, to reduce innate immune activation in an in vitro model of microglial activation using the blood product hemoglobin (Hgb). We then utilized azithromycin in our in vivo model of IVH, using intraventricular blood injection into the lateral ventricle of post-natal day 5 rat pups. In both models, azithromycin modulated innate immune activation by several outcome measures including mitochondrial bioenergetic analysis, cytokine expression and flow cytometric analysis. This suggests that azithromycin, which is safe for neonates, could hold promise for modulating innate immune activation after IVH.

144 EXPRESSION OF ACETYL COENZYME A CARBOXYLASE α (ACCα) IN FELINE, CANINE AND PORCINE OOCYTES

High lipid content in in vitro–derived embryos of several species is associated with poor developmental potential and cryosurvival of oocytes. Lipid content of oocytes varies among species and embryonic lipid content is further influenced by the culture environment. In spite of the variation among species, the relative contribution of de novo lipid synthesis during oocyte maturation or subsequent embryonic development is unknown. In the present study, we evaluated the expression of acetyl coenzyme A carboxylase (ACCα), the key rate-limiting enzyme of lipogenesis, in oocytes of 3 species with high lipid content. Ovaries of dogs and cats were collected from a local veterinary clinic and those of pigs from an abattoir. Cat and dog oocytes were recovered by the slicing method of the ovaries. Porcine oocytes were recovered by aspiration of ovarian follicles. Immediately after collection, oocytes were fixed for 30 min using a solution of 10% neutral buffered formalin. The ACCα enzyme expression was evaluated in porcine, cat and dog oocytes by immunofluorescence using a goat anti-human ACCα primary antibody followed by fluorescein isothiocyanate-conjugated anti-goat secondary antibody. The study was replicated, with negative controls, 3 times using ≥30 oocytes per species. Messenger RNA expression of ACCα gene was also evaluated in pig oocytes. The RNA was isolated from fat tissue, pooled good-quality oocytes (n = 30), pooled poor-quality oocytes (n = 30) and cumulus cells using the RNeasy Micro kit (Qiagen, Valencia, CA, USA) according to the manufacturer's instructions. Complementary DNA was synthesised from 200 ng of RNA using Quantitect reverse-transcription kit (Qiagen) according to the manufacturer's instructions. Real-time PCR assays were carried out in duplicate and expression of ACCα mRNA levels relative to fat was determined. Oocytes and cumulus investment in cats, dogs and pigs strongly expressed ACCα. Expression of the protein was uniformly distributed through the entire ooplasm. The mRNA expression of ACCα in good- and poor-quality oocytes and cumulus cells relative to fat tissue was 11.5, 1.4 and 40.1%, respectively. Further studies are warranted on the dynamics of expression of ACC during in vitro maturation and the functional activity of the enzyme. We extend our appreciation to the Alabama Animal Alliance Inc. (Montgomery) for providing us with dog and cat ovaries; the Lambert-Powell Meats Laboratory of Auburn University for donating pig ovaries; and Dr. James Webster, Dr. Tsegaye Habtemariam and Dr. Abdalla Eljack for administrative support.

Antagonism by antimuscarinic and neuroleptic compounds at the five cloned human muscarinic cholinergic receptors expressed in Chinese hamster ovary cells

We determined the affinity and selectivity of binding for 24 compounds: nine antimuscarinics (including some antiparkinson drugs) and 15 neuroleptics (including the atypical compounds clozapine, fluperlapine, melperone, rilapine, risperidone, tenilapine, tiosperone and zotepine) at the five human muscarinic receptor subtypes expressed in Chinese hamster ovary cells. Equilibrium dissociation constants (Kd) were obtained from competitive radioligand binding studies with [3H]quinuclidinyl benzilate and membranal preparations of these cells. As expected, QNB had the highest affinity of the compounds studied at the five receptor subtypes and was not selective (Kd ranged from 0.027-0.088 nM). Benztropine had the next highest affinity of the antimuscarinic compounds and thioridazine had the highest affinity of the neuroleptics. Among the antiparkinson drugs, biperiden was the only one selective for the m1 subtype; and among the neuroleptics, the atypical drug clozapine was also selective for the m1 subtype. This selectivity may explain clozapine's unusual efficacy in refractory schizophrenic patients and its low incidence of extrapyramidal side effects. However, because most other atypical neuroleptics studied lacked high affinity and selectivity at muscarinic receptor subtypes, it is likely that other mechanisms are involved as well.

Phorbol esters inhibit agonist-stimulated phosphoinositide hydrolysis in neuronal primary cultures

The effects of phorbol esters on neurotransmitter-stimulated phosphoinositide (PI) hydrolysis in neurons in primary culture were investigated. Ten-day-old neuronal cultures were incubated with [3H]inositol for 2-3 days, exposed to phorbol esters, and the release of [3H]inositol phosphates was measured in the presence of 10 mM lithium. Pretreatment of the neuronal cultures with 1 microM phorbol myristate acetate (PMA) inhibited alpha 1, muscarinic, and glutamate receptor-mediated PI hydrolysis in a time-dependent manner with maximal inhibition observed after a 20-30 min preincubation. The active beta-phorbol didecanoate inhibited stimulated PI hydrolysis, but its stereo-isomer alpha-phorbol didecanoate was without effect at 1 microM. PMA was about 10 times more potent at inhibiting PI hydrolysis stimulated by norepinephrine and glutamate compared to carbachol. The order of potency of the various phorbol esters for inhibition of stimulated PI hydrolysis and the differences between active and inactive stereoisomers suggests that the activation of protein kinase C may mediate the inhibitory effects. Thus, stimulation of neuronal protein kinase C may represent a mechanism for the regulation of agonist-stimulated PI hydrolysis.