Joseph Yanai

Acceleration of wound healing by topical application of honey: An animal model

Commercial unboiled honey was applied topically to open wounds of 12 mice. Twelve other mice served as a control group and their wounds were dressed with saline solution only. Wound healing was judged histopathologically by measuring the thickness of granulation tissue, epithelization from the periphery of the wound, and the size of the open wounds. The animals were killed 3, 6, and 9 days from the day they were wounded and treated, and their wounds were examined histopathologically. According to the three mentioned criteria, wounds of the honey-treated animals healed much faster than the wounds of the control animals (p less than 0.001). Unboiled commercial honey seems to accelerate wound healing when applied topically due to its energy-producing properties, its hygroscopic effect on the wound, and its bacteriocidic properties. Our results suggest that honey applied topically on open wounds accelerates the healing process.

Alterations in Hippocampal Cholinergic Receptors and Hippocampal Behaviors After Early Exposure to Nicotine

Mice were exposed to nicotine prenatally by injecting the mother with 1.5 mg/kg nicotine SC twice daily on gestation days 9-18 (PreN mice) or neonatally by daily SC injections of 1.5 mg/kg nicotine on postnatal days 2-21 (NeoN mice). At age 50 days, hippocampal muscarinic receptors Bmax of PreN and NeoN mice were 58% and 79% above control, respectively (p less than 0.01); Kd was unaffected by early nicotine exposure. Eight-arm maze performance of nicotine-exposed animals fell behind control level. Both PreN and NeoN made approximately 10% less correct responses in the first eight trials than controls throughout the test period (p less than 0.01). By the last day of testing, PreN needed 23% and NeoN 31% more trials than controls to enter all arms (p less than 0.001). In addition, PreN needed 35 and NeoN 42% more days than controls to reach criterion (p less than 0.05). Similarly, while 61% of controls reached criterion by day 6 only 17% of PreN and 25% of NeoN reached criterion (p less than 0.01). In the Morris maze, PreN needed from 43-119% more time to reach the platform (p less than 0.001). In the spatial probe test, PreN animals made 35% fewer crosses over the area of the missing platform (p less than 0.001). The study suggests that nicotine administered to the fetus or neonate alters septohippocampal chemistry and induces deficits in hippocampus-related behaviors. The possible reversal of the behavioral changes by manipulating the cholinergic innervations should be the subject of future investigations.

Deficits in Development of Central Cholinergic Pathways Caused by Fetal Nicotine Exposure: Differential Effects on Choline Acetyltransferase Activity and (3H)Hemicholinium-3 Binding

Nicotine has been hypothesized to induce neurobehavioral teratology by mimicking prematurely the natural developmental signals ordinarily communicated by the ontogeny of cholinergic synaptic transmission. In the current study, the effects of fetal nicotine exposure (2 mg/kg/day or 6 mg/kg/day) on development of central cholinergic pathways were examined in striatum and hippocampus of animals exposed from gestational days 4 through 20, using maternal infusions with osmotic minipumps. Brain region weights and choline acetyltransferase activity, an enzymatic marker for development of cholinergic nerve terminals, were within normal limits in the nicotine-exposed animals. However, development of [3H]hemicholinium-3 binding which labels the presynaptic high affinity cholinergic transporter, was deficient in both striatum and hippocampus. Abnormalities occurred during two distinct phases; in the early neonatal period, when [3H]hemicholinium-3 binding sites are transiently overexpressed, and during or after the period of rapid synaptogenesis, when binding in controls is rising consequent to the increase in nerve impulse activity. These data thus indicate that fetal nicotine exposure, even at doses that do not cause overt signs of maternal/fetal/neonatal toxicity or growth impairment, influences both specific gene expression of cholinergic nerve terminal markers, as well as indices of neuronal function. Comparison of regional selectivity at the two dose levels indicated greater sensitivity of the striatum, a region with a prenatal peak of neuronal mitosis, as compared to hippocampus, where mitosis peaks postnatally; the regional differences are consistent with vulnerability to nicotine during a critical phase of cell development.

Differential development of cholinergic nerve terminal markers in rat brain regions: implications for nerve terminal density, impulse activity and specific gene expression.

During critical developmental periods, cholinergic activity plays a key role in programming the development of target cells. In the current study, ontogeny of cholinergic terminals and their activity were contrasted in 4 brain regions of the fetal and neonatal rat using choline acetyltransferase activity, which is unresponsive to changes in impulse flow, and [3H]hemicholinium-3 binding, which labels the high-affinity choline transporter that upregulates in response to increased neuronal stimulation. In all 4 regions (cerebral cortex, midbrain + brainstem, striatum, hippocampus) choline acetyltransferase activity increased markedly from late gestation through young adulthood, but generally did so in parallel with the expansion of total membrane protein, reflective of axonal outgrowth and synaptic proliferation. In contrast, [3H]hemicholinium-3 binding was extremely high in late gestation and immediately after birth, declined in the first postnatal week and then rose again into young adulthood. The ontogenetic changes reflected alterations primarily in the number of binding sites (Bmax) and not in binding affinity. Only the latter phase of development of [3H]hemicholinium-3 binding corresponded to the ontogenetic changes in choline acetyltransferase activity; in the hippocampus, there were disparities even in young adulthood, where [3H]hemicholinium-3 binding showed a spike of activity centered around the 5th to 6th postnatal week, whereas choline acetyltransferase did not. Correction of binding for membrane protein development did not eliminate any of the major differences in developmental patterns between the two markers. These results suggest that development of the choline transporter binding site is regulated independently of the outgrowth of the bulk of cholinergic nerve terminals.(ABSTRACT TRUNCATED AT 250 WORDS)

The antinociceptive effect of fluvoxamine

The authors conducted a study in order to evaluate the antinociceptive effects of the serotonin-selective reuptake inhibitor (SSRI) antidepressant fluvoxamine and its interaction with various opioid receptor subtypes. Male ICR mice were tested with a hotplate analgesia meter. Fluvoxamine elicited antinociceptive effect in a dose-dependent manner following i.p., i.t. and i.c.v. injection. Naloxone 10 mg/kg s.c. did not abolish the fluvoxamine antinociceptive effect. At the next stage fluvoxamine was administered together with various agonists of opioid receptors. When administered together with opiates, fluvoxamine significantly potentiated analgesia at the kappa(3)-opioid receptor subtype (P < .005) and to a lesser extent, at the mu-, delta-, and kappa(1)-opioid receptors. We conclude that fluvoxamine alone induces an antinociceptive effect. This effect is mediated by non-opioid mechanism of action. These results suggest a potential role for fluvoxamine in the management of pain when co-administered with opioids at low doses.

Cell Signaling as a Target and Underlying Mechanism for Neurobehavioral Teratogenesis

Abstract: A wide variety of drugs and chemicals elicit neurobehavioral teratogenesis. Surprisingly, however, despite the obvious differences among unrelated compounds, the behavioral outcomes often display striking similarities, such as cognitive and attentional deficits. Recent studies of drugs of abuse (heroin, nicotine, barbiturates) and environmental toxins (environmental tobacco smoke, pesticides, metals) suggest that, regardless of the originating mechanism for perturbation of brain development, disparate neuroteratogens converge downstream on common families of alterations, characterized by changes in the expression and/or activity of the cell‐signaling molecules that are essential to neuronal differentiation and synaptic communication. Identification of these common targets may help in the design of pharmacologic interventions that, administered in adulthood, can reverse the impact of exposure to neurobehavioral teratogens.

Alterations in septohippocampal cholinergic innervations and related behaviors after early exposure to heroin and phencyclidine

Mice were exposed to diacetylmorphine (heroin) or phencyclidine (PCP) prenatally or neonatally. At a later age, they were tested for hippocampus-related behavioral deficits and concomitant alterations in the septohippocampal cholinergic innervations. Actually, this is an application of the previously established phenobarbital neuroteratogenicity model to heroin and PCP. Prenatal exposure was accomplished transplacentally by injecting the mother 10 mg/kg heroin or PCP on gestation days 9-18. Neonatal administrations were applied directly by injections of 10 mg/kg of either drug to the pups between neonatal days 2-21. At the age of 50 days, mice exposed to heroin and PCP prenatally exhibited a 107% and 159% increase in their muscarinic cholinergic receptors Bmax, respectively. Neonatal exposure to heroin or PCP caused an 83% and 76% increase in the receptors respectively. On the behavioral level, both prenatal and neonatal exposure to heroin or PCP reduced performance in the hippocampus related eight-arm maze and Morris mazes. Depending on the drug, the test and the period of drug administration, the reduction ranged between 10% and 75%. The results suggest that heroin and PCP induce alterations in the septohippocampal cholinergic innervations and in related behavioral performance. Further studies are necessary in order to connect the biochemical and behavioral events in causal relationships.

Strain and sex differences in the rat brain

The brains of female and male Wistar (W) rats were larger than the brains of Long-Evans (LE) rats at all ages and males had larger brains than females (p

Hippocampal cholinergic alterations and related behavioral deficits after early exposure to phenobarbital

Mice were exposed to phenobarbital (PhB) prenatally and neonatally. Prenatal exposure was accomplished by feeding the mother PhB (3 g/kg milled food) on gestation days 9-18. Neonatal exposure was accomplished by daily injections of 50 mg/kg sodium PhB directly to the pups on days 2-21. Long-term biochemical alterations in the pre- and postsynaptic septohippocampal system, as well as related behavioral deficits, were assessed in the treated animals. Significant increase in B(max) values for binding of [3H]QNB to muscarinic cholinergic receptors was obtained on both ages 22 and 50 in prenatally (40-90%, respectively, p less than 0.001) and neonatally exposed (58-89%, p less than 0.001) mice whereas Kd remained normal. Similarly, a significant increase of inositol phosphate (IP) formation in response to carbachol was found after both prenatal and neonatal exposure to PhB (p less than 0.05). No alterations in choline acetyltransferase (ChAT) activity were observed in the prenatally or neonatally treated animals. The early exposed mice showed deficits in the performance in Morris water maze, a behavior related to the septohippocampal pathway. The results suggest that early exposure to PhB induces alterations in postsynaptic components of the hippocampal cholinergic system and concomitantly to impairment in hippocampus-related behavior.

Fetal nicotine exposure alters ontogeny of M1-receptors and their link to G-proteins.

Prenatal nicotine exposure has been shown to disrupt the development of cholinergic presynaptic tone and behaviors mediated through muscarinic cholinergic receptors. The current study examines nicotines effects on ontogeny of postsynaptic muscarinic M1-receptors in rat striatum and hippocampus after continuous maternal infusions of 2 mg/kg/day or 6 mg/kg/day from gestational days 4 through 20. Although brain region weights were unaffected by nicotine exposure, significant alterations in receptor development and receptor regulation by G-proteins were found. Postnatal development of striatal M1-receptor binding, as identified with [3H]pirenzepine, was significantly impaired with either of the fetal nicotine regimens. Treatment with 2 mg/kg/day also produced alterations in striatal receptor affinity state, characterized by enhanced ability of an agonist (oxotremorine-M) to displace [3H]pirenzepine; raising the dose to 6 mg/kg/day masked the affinity shift by affecting G-protein regulatory mechanisms, such that addition of the GTP analog, GppNHp, produced a larger decrease in agonist affinity. In the hippocampus, no such effects on receptor binding, affinity state, or G-protein regulation were seen with either regimen. These data thus indicate that fetal nicotine exposure, even at doses that do not cause overt signs of maternal/fetal/neonatal toxicity or growth impairment, influences cholinergic receptor development and regulation of cell signaling mediated by G-proteins. The selectivity of effects toward M1-receptors in the striatum, a region with a prenatal peak of neuronal mitosis, as compared to hippocampus, where mitosis peaks postnatally, suggests that vulnerability to nicotine involves a critical phase of cell development, rather than being targeted toward receptors of a given subtype.