Inhibition of nitric oxide synthase enhances cocaine's developmental toxicity: vascular and CNS effects.

Ischemia and/or reperfusion injury from free radicals may cause cocaine's toxicity, including its effect upon neurobehavioral development. We previously used salicylate to measure hydroxyl free radicals in chick embryos exposed to cocaine. The combination was more toxic than cocaine alone.

HPA axis dysregulation following prenatal opiate exposure and postnatal withdrawal.

We examined the effects of prenatal exposure to the long acting opiate l-alpha-acetylmethadol (LAAM) followed by postnatal withdrawal on hypothalamic-pituitary-adrenal (HPA) axis reactivity in neonatal and adult rats and anxiety-like behavior in adult rats. Female rats were treated with LAAM (0, 0.2, or 1.

Suppressed fever and hypersensitivity responses in chicks prenatally exposed to opiates.

We have established procedures to reliably induce opiate dependence in the chick embryo via in ovo injection, early in embryonic development, of the long-acting and potent opiate N-desmethyl-l-alpha-noracetylmethadol (NLAAM). Prior studies found that there is continual exposure to NLAAM throughout embryogenesis and shortly after hatching there are signs of spontaneous withdrawal. In the present study, we used three doses of NLAAM (2.

Vasoconstriction caused by cocaine is enhanced by sodium salicylate: is inducible nitric oxide synthase mRNA related?

We have previously found that sodium salicylate (NaSal), injected into chicken eggs at nontoxic doses used for quantifying hydroxyl free radicals in hearts and brains of embryos, caused or exacerbated hemorrhages and dramatically reduced hatchability when combined with cocaine (Coc). It has also been reported that inducible nitric oxide synthase (iNOS) gene expression is altered in brain in response to vascular damage and inflammation. In this study we measured diameters of membrane-bound blood vessels (BV) before and after pretreatment with saline (NaCl) or NaSal (100 mg/kg egg), followed by infusion of either NaCl or Coc HCl (total of 67.

Prenatal opiate withdrawal activates the chick embryo hypothalamic pituitary-adrenal axis and dilates vitelline blood vessels via serotonin(2) receptors.

Opiate withdrawal during pregnancy may occur because of voluntary or forced detoxification, or from rapid cycling associated with exposure to short-acting "street" opiates. Thus, animal modeling of prenatal withdrawal and development of potential therapeutic interventions is important. Direct developmental effects of opiates and/or withdrawal can be studied using a chick model.

Embryonic "binge" cocaine exposure alters neural-immune and neural-endocrine interactions in young chickens: involvement of serotonin(2) receptors.

As part of our characterization of the developmental consequences of prenatal cocaine exposure, cocaine was injected into eggs containing viable chicken embryos on embryonic day (E) 18 and the fever response to the endotoxin lipopolysaccharide (LPS) and a delayed-type hypersensitivity response to phytohemagglutinin (PHA) were assessed postnatally. E18 cocaine exposure did not affect basal body temperature. LPS induced a fever in the chicks at 4 h post-injection on post-hatch day (D) 4 and 2 h post-injection on D24.

Cocaine and salicylate: documentation of hydroxyl radical formation in hearts and brains of 18-day-old chick embryos and unexpected interactive toxicity.

Rationale: Multiple low doses of cocaine (COC) may cause intermittent vasoconstriction and reperfusion, leading to elevations in damaging reactive oxygen species, such as hydroxyl free radicals (*OH). Salicylate may offer protection because it reacts with *OH and/or because of its anti-inflammatory actions.

Objective: To measure *OH concentrations in hearts and brains of chicken embryos exposed to multiple, small doses of COC, and to determine if otherwise non-toxic doses of sodium salicylate (NaSal) protected against the marginal but significant reduction in hatchability caused by a model of "binge" COC exposure.

Embryonic cocaine exposure and corticosterone: serotonin(2) receptor mediation.

Cocaine activates the mature hypothalamic-pituitary-adrenal (HPA) axis, increasing corticosterone concentrations in animals and humans and serotonin(2) receptors (5-HT(2)) are involved in this effect. Although prenatal cocaine exposure is associated with altered responsiveness of the HPA axis to "stress" and serotonergic compounds postnatally, it is unknown whether cocaine directly activates the embryonic HPA axis or if 5-HT(2) receptors are involved. Domestic chicken eggs with viable embryos were exposed to either the 5-HT(2) receptor agonist dimethoxyiodophenylaminopropane (DOI: 0.

Salicylate and cocaine: interactive toxicity during chicken mid-embryogenesis.

Increased free radical production, due to ischemia and reperfusion, has been postulated as a cause of cocaine's (COC) developmental toxicity. Salicylate reacts with hydroxyl free radicals (*OH) to form stable, quantifiable reaction products, which can be measured with high-pressure liquid chromatography (HPLC). To determine if chicken embryos' brains and hearts were exposed to increased *OH concentrations after injection of COC, an injection of a nontoxic dose of sodium salicylate (NaSAL, 100 mg/kg egg, or 5 mg/egg), followed by 5 injections of COC (13.

Late embryonic ritanserin exposure fails to alter normal responses to immune system stimulation in young chicks.

Prior studies in our laboratory have demonstrated that prenatal treatment with the serotonin2 (5-HT2) antagonist ritanserin is effective in blocking some of the lethal, dysmorphic, cardiovascular, and behavioral consequences of excessive direct or indirect stimulation of 5-HT2 receptors in the developing chicken. The efficacious dose range for ritanserin in these studies had very little or no effect on the above measures of toxicity when administered alone. In the present study, we extend our characterization of ritanserin's potential toxicity, or lack thereof, to include the normal behavioral and endocrine responses to immune system stimulation by the endotoxin lipopolysaccharide (LPS).

OCD-Like behaviors caused by a neuropotentiating transgene targeted to cortical and limbic D1+ neurons.

To study the behavioral role of neurons containing the D1 dopamine receptor (D1+), we have used a genetic neurostimulatory approach. We generated transgenic mice that express an intracellular form of cholera toxin (CT), a neuropotentiating enzyme that chronically activates stimulatory G-protein (Gs) signal transduction and cAMP synthesis, under the control of the D1 promoter. Because the D1 promoter, like other CNS-expressed promoters, confers transgene expression that is regionally restricted to different D1+ CNS subsets in different transgenic lines, we observed distinct but related psychomotor disorders in different D1CT-expressing founders.

Voltage associated with spontaneous embryonic motility in the developing chicken: an automated characterization during mid-late embryogenesis.

Movement of developing chicken embryos and their associated membranes generates voltage detectable with electrodes inserted just beneath the eggshell. Use of such voltages as a motility indicator offers an embryonic behavioral assessment method less subjective and invasive than observational methods using windows that disrupt substantial portions of the eggshell. We used a computerized signal recording and processing procedure to compare voltages from embryonic Day 12 (E12), E15, and E18 chicken eggs with embryos, assessed on the same day.

Open-field and LPS-induced sickness behavior in young chickens: effects of embryonic cocaine and/or ritanserin.

Exposure to drugs of abuse during embryogenesis may adversely affect nervous, immune, and endocrine systems development. We compared exposure on embryonic day 18 (E18) by single or multiple cocaine (COC) injections (56.25 mg/kg total dose for both) or saline on hatching and activity measures.

Acute heat stress model of seizures in weanling rats: influence of prototypic anti-seizure compounds.

The present study tested the therapeutic potential for prototype anti-epilepsy drugs using an animal model of infantile febrile seizures. The model consisted of immersion of weanling rats (21 days old) in a 45 degrees C water bath for a maximum of 4 min (four exposures over a 2 week period) and observing for the progression to stage-5 seizures. All compounds were administered orally at the respective ED50 for prevention of seizures in the maximal electroshock (MES) test.

Behavioral and neuroendocrine assessment of ritanserin exposure in the developing chicken: lack of toxicity at effective doses.

The 5-HT2 antagonist ritanserin (RIT) is undergoing Phase III clinical trials for the treatment of substance abuse disorders. RIT has also shown preclinical therapeutic potential for attenuating or blocking lethal and/or toxic effects of exposure to cocaine or the selective 5-HT2 agonist dimethoxyiodophenyl-aminopropane (DOI) in the developing chicken. To assess the potential toxicity ("side effects") of RIT itself during development, we exposed chicken embryos to 0, 0.

Relationships between midembryonic 5-HT2 agonist and/or antagonist exposure and detour learning by chickens.

The importance of serotonin (5-HT) as both a transmitter and a regulatory signal during development of many species is well established. The availability of 5-HT receptor subtype agonists and antagonists will enable pharmacological dissection of the importance of one or more of the 5-HT receptors for their involvement in the mediation of developmental insults by drugs that are less selective but include actions upon serotonergic function. Such insults include exposure to cocaine or opiate withdrawal, both of which are blocked or attenuated by 5-HT2 antagonists.

Evidence for a serotonin-mediated effect of cocaine causing vasoconstriction and herniated umbilici in chicken embryos.

Some of cocaine (COC)'s pathophysiological effects on exposed embryos likely result from its vasoconstrictive action, and serotonin2 (5-HT2) agonists such as dimethoxyiodophenylaminopropane (DOI) can mimic these effects. Infusions of COC (5 mg/kg/min) or DOI (0.5 mg/kg/min) for 15 min into chicken eggs with embryos on E15 caused a significant reduction in blood vessel diameters (14 and 30%, respectively).

Ontogeny of glucocorticoid receptors in the hyperstriatum-hippocampus-parahippocampal area and optic tectum of the embryonic chicken (Gallus domesticus) brain.

The importance of glucocorticoids and their perturbation during development is an active research area. Developmental insults, including direct and indirect consequences of exposure to drugs of abuse or withdrawal from them, may act upon or via the neuroendocrine axis of the pregnant experimental subject (e.g.

Ritanserin blocks DOI-altered embryonic motility and posthatch learning in the developing chicken.

Developing chicken embryos exposed to cocaine show altered motility, hatchability, and posthatch detour learning. Pretreating such subjects with the serotonin2 (5-HT2) antagonist ritanserin (RIT) can block the motility suppression and reduced hatchability, indicating 5-HT2 receptor involvement in these cocaine effects. To study behavioral consequences of more selective 5-HT2 receptor stimulation and its blockade during development and to compare such exposure with that of cocaine, we injected eggs with 15-day-old chicken embryos with the 5-HT2 agonist dimethoxyiodophenylaminopropane (DOI, 1.

Excessive stimulation of serotonin2 (5-HT2) receptors during late development of chicken embryos causes decreased embryonic motility, interferes with hatching, and induces herniated umbilici.

The existence and functional significance of 5-HT2 receptors in chicken embryos was studied by injecting the selective agonist dimethoxyiodophenylaminopropane (DOI), alone or in conjunction with the selective 5-HT2 antagonist ritanserin (RIT), into domestic chicken eggs with embryos of varying ages. DOI caused dose-dependent reductions in hatchability and herniated umbilici in hatchlings. These effects were observed after injection early, mid, or late during embryonic development, with evidence of the toxic effects of DOI being greater in older embryos, probably due to 5-HT2 receptor activation late in development, even after injecting DOI as early as on day 3 of embryogenesis.

Potential efficacy and toxicity of GM1 ganglioside against trimethyltin-induced brain lesions in rats: comparison with protracted food restriction.

GM1 ganglioside (one week each at 10, 5, and 2.5 mg GM1/kg per day, ip) or gradual food restriction leading to a reduction in body weight to 75% of control were tested for their ability to block or reverse histopathologic and behavioral effects of trimethyltin (TMT) poisoning in rats. TMT (a single oral gavage of 6.

Interaction between mitogens upon intracellular Ca2+ pools in murine fibroblasts.

A comparison of the effect of platelet-derived growth factor (PDGF) and bombesin on intracellular Ca2+ stores was carried out in Swiss 3T3 cells loaded with Fura-2. It was found that the tumor promoter thapsigargin (Tg) almost completely inhibited both the PDGF- and the bombesin-induced intracellular Ca2+ concentration ([Ca2+]i) rise, indicating that the two mitogens mobilize Ca2+ from intracellular pool(s) sensitive to the tumor promoter. It was also found that pre-treatment with PDGF almost totally and persistently (up to at least 30 min) inhibited the bombesin-, Tg- and ionomycin-induced rise in [Ca2+]i, whereas pre-treatment with bombesin had only a partial inhibitory effect on the PDGF, Tg and ionomycin [Ca2+]i response, both in the absence and in the presence of external Ca2+.

Modulation of the behavioural effects of interleukin-1 in mice by nitric oxide.

Interleukin-1 is a cytokine which mediates the host response to infection and inflammation and is responsible for sickness behaviour. Inhibition of nitric oxide synthase activity by N omega nitro-L-Arginine-Methyl-ester (30 mg kg-1, i.p.

Ganglioside treatment partially counteracts neurotoxic effects of trimethyltin but may itself cause neurotoxicity in rats: experimental results and a critical review.

We have demonstrated a deficit in working memory and/or consolidation of information in working memory into reference memory by a single oral dose of the neurotoxin trimethyltin(TMT). Moreover, TMT causes loss of hippocampal corticosterone receptors and increases brain glial fibrillary acidic protein(GFAP), an index of the astrocytic reaction to diverse types of CNS lesions. We tried to block the TMT-induced cognitive deficit and these biochemical markers by treating rats with purified mixed gangliosides (GS) for 21 days, starting 2 days before the TMT treatment.

Acute opiate withdrawal in rats undernourished during infancy: impact of the undernutrition method.

Acute morphine withdrawal was assessed in adult rats following early postnatal undernutrition produced by two different methods (Large Litter procedure-20 pups/litter and Modified Slob procedure-rats cross-fostered on days 2, 4, and 6 to nonlactating dams for 24-hour periods). Response rates were first stabilized on a FR16 operant schedule. A single dose of morphine (20 mg/kg) was then administered, followed 4 h later by a single injection of naloxone (2.