Morphine treatment during pregnancy modulates behavioral selection in lactating rats

Previous studies have demonstrated that treatment of postpartum female rats with morphine inhibits maternal behavior and stimulates foraging. Exposure to drugs of abuse may result in a progressive enhancement of their reinforcing effects. Puerperal treatment with morphine leads to reverse tolerance to this drug. The present study investigated whether repeated morphine treatment during late pregnancy may influence the effects of different morphine dosages on behavioral selection in lactating rats. Females were simultaneously exposed to pups and insects, and the choice between taking care of the pups and hunting insects was observed. Female Wistar rats were treated with morphine (3.5 mg/kg/day, subcutaneous [s.c.]) or saline for 5 days beginning on pregnancy day 17. On day 5 of lactation, animals were acutely challenged with morphine (0.5, 1.0, or 1.5 mg/kg, s.c.; MM0.5, MM1.0, and MM1.5 groups, respectively) or saline (MS group) and tested for predatory hunting and maternal behavior. Control groups were pretreated with saline and challenged with morphine (SM0.5, SM1.0, and SM1.5 groups) or saline (SS group). Animals treated with morphine during late pregnancy and acutely challenged with 1.0 mg/kg morphine (MM1.0 group) exhibited significantly decreased maternal behavior and enhanced hunting. This effect was not evident with the 0.5 mg/kg dose. The 1.5 mg/kg morphine dose decreased maternal behavior and increased hunting in both the MM1.5 group and in animals challenged with morphine after previous saline treatment (SM1.5 group). These results provide evidence of plasticity of the opioidergic role in behavioral selection during lactation. (C) 2010 Elsevier Inc. All rights reserved.

Changes in extracellular levels of glutamate in the nucleus accumbens after ethanol-induced behavioral sensitization in adolescent and adult mice

Repeated administration of low doses of ethanol gradually increases locomotor responses to ethanol in adult Swiss mice. This phenomenon is known as behavioral sensitization. However, we have shown that adolescent Swiss mice show either behavioral tolerance or no sensitization after repeated ethanol injections. Although the mesolimbic dopamine system has been extensively implicated in behavioral sensitization, several studies have demonstrated an important role of glutamatergic transmission in this phenomenon. In addition, relatively few studies have examined the role of developmental factors in behavioral sensitization to ethanol. To examine the relationship between age differences in behavioral sensitization to ethanol and the neurochemical adaptations related to glutamate within nucleus accumbens (NAc), in vivo microdialysis was conducted in adolescent and adult Swiss mice treated with ethanol (1.8 g/kg) or saline for 15 days and subsequently challenged with an acute dose (1.8 g/kg) of ethanol 6 days later. Consistent with previous findings, only adult mice demonstrated evidence of behavioral sensitization. However, ethanol-treated adolescent mice demonstrated a 196.1 +/- 40.0% peak increase in extracellular levels of glutamate in the NAc after ethanol challenge in comparison with the basal values, whereas ethanol-treated adult mice demonstrated a 52.2 +/- 6.2% reduction in extracellular levels of glutamate in the NAc after ethanol challenge. These observations suggest an age-dependent inverse relationship between behavioral and glutamatergic responses to repeated ethanol exposure. (C) 2011 Elsevier Inc. All rights reserved.

Anabolic-androgenic steroid treatment induces behavioral disinhibition and downregulation of serotonin receptor messenger RNA in the prefrontal cortex and amygdala of male mice

Nandrolone is an anabolic-androgenic steroid (AAS) that is highly abused by individuals seeking enhanced physical strength or body appearance. Supraphysiological doses of this synthetic testosterone derivative have been associated with many physical and psychiatric adverse effects, particularly episodes of impulsiveness and overt aggressive behavior. As the neural mechanisms underlying AAS-induced behavioral disinhibition are unknown, we investigated the status of serotonergic system-related transcripts in several brain areas of mice receiving prolonged nandrolone administration. Male C57BL/6J mice received 15 mg/kg of nandrolone decanoate subcutaneously once daily for 28 days, and different sets of animals were used to investigate motor-related and emotion-related behaviors or 5-HT-related messenger RNA (mRNA) levels by real-time quantitative polymerase chain reaction. AAS-injected mice had increased body weight, were more active and displayed anxious-like behaviors in novel environments. They exhibited reduced immobility in the forced swim test, a higher probability of being aggressive and more readily attacked opponents. AAS treatment substantially reduced mRNA levels of most investigated postsynaptic 5-HT receptors in the amygdala and prefrontal cortex. Interestingly, the 5-HT(1B) mRNA level was further reduced in the hippocampus and hypothalamus. There was no alteration of 5-HT system transcript levels in the midbrain. In conclusion, high doses of AAS nandrolone in male mice recapitulate the behavioral disinhibition observed in abusers. Furthermore, these high doses downregulate 5-HT receptor mRNA levels in the amygdala and prefrontal cortex. Our combined findings suggest these areas as critical sites for AAS-induced effects and a possible role for the 5-HT(1B) receptor in the observed behavioral disinhibition.

Investigating the Effects of Mifepristone (RU486) in the Behavioral, Hormonal and Central Responses to Acute Stress

Depression is associated with glucocorticoid hypersecretion, due to dysfunction of the hypothalamo-pituitary-adrenocorticol axis (HPA-axis). Because excess glucocorticoids are associated with depressive-like features in humans, glucocorticoid receptor antagonists are currently being tested for antidepressant efficacy in clinical trials. In the current study the hypothesis that mifepristone (RU486), a glucocorticoid receptor antagonist, would decrease the neuroendocrine and central HPA-axis responses to an acute stressor and attentuate depressive like behavior in an animal model of behavioral helplessness (forced swim test) was tested. Adult male rats were treated with 10 mglkg RU486 (subcutaneous) for five days and then exposed to a IO-minute forced swim test (FST), conducted in Plexiglas cylinders. FST sessions were videotaped for later analysis of behavioral immobility. Plasma ACTH and corticosterone CORT were measured at 15min and 90min after FST cessation. Animals were perfused and brains were collected for immunocytochemical assessment of c-Fos expression in the medial prefrontal cortex (mPFC), a brain region implicated in both depression and central control of the HPA axis. RU486 significantly decreased peak ACTH and CORT concentrations following FST exposure. In addition, glucocorticoid negative feedback was at1enuated in RU486-treated animals exposed to the FST. Exposure to FST alone induced c-FOS expression in the mPFC, as measured by the number of c-Fos positive neurons. Treatment with RU486 significantly increased the number of rnPFC c-Fos positive cell following FST exposure. The behavioral data obtained from FST paradigm, demonstrated that RU486 decreased immobility in the FST illustrating the potential efficacy of this drug as an antidepressant. Collectively these data suggest that RU486 dampens HPA-axis responses to stress, possibly by enhancing the excitability of stress-inhibitory neurons in the mPFC. This is particularly exciting, given the fact that this neural region is associated with decreased neural activity during depression in humans.

Insuring cleaner oceans: the economics of oil pollution prevention

The current system of controlling oil spills involves a complex relationship of international, federal and state law, which has not proven to be very effective. The multiple layers of regulation often leave shipowners unsure of the laws facing them. Furthemore, nations have had difficulty enforcing these legal requirements. This thesis deals with the role marine insurance can play within the existing system of legislation to provide a strong preventative influence that is simple and cost-effective to enforce. In principle, insurance has two ways of enforcing higher safety standards and limiting the risk of an accident occurring. The first is through the use of insurance premiums that are based on the level of care taken by the insured. This means that a person engaging in riskier behavior faces a higher insurance premium, because their actions increase the probability of an accident occurring. The second method, available to the insurer, is collectively known as cancellation provisions or underwriting clauses. These are clauses written into an insurance contract that invalidates the agreement when certain conditions are not met by the insured The problem has been that obtaining information about the behavior of an insured party requires monitoring and that incurs a cost to the insurer. The application of these principles proves to be a more complicated matter. The modern marine insurance industry is a complicated system of multiple contracts, through different insurers, that covers the many facets of oil transportation. Their business practices have resulted in policy packages that cross the neat bounds of individual, specific insurance coverage. This paper shows that insurance can improve safety standards in three general areas -crew training, hull and equipment construction and maintenance, and routing schemes and exclusionary zones. With crew, hull and equipment, underwriting clauses can be used to ensure that minimum standards are met by the insured. Premiums can then be structured to reflect the additional care taken by the insured above and beyond these minimum standards. Routing schemes are traffic flow systems applied to congested waterways, such as the entrance to New York harbor. Using natural obstacles or manmade dividers, ships are separated into two lanes of opposing traffic, similar to a road. Exclusionary zones are marine areas designated off limits to tanker traffic either because of a sensitive ecosystem or because local knowledge is required of the region to ensure safe navigation. Underwriting clauses can be used to nullify an insurance contract when a tanker is not in compliance with established exclusionary zones or routing schemes.

Two Essays on the economics of Education

We develop a job-market signaling model where signals may convey two pieces of information. This model is employed to study the GED exam and countersignaling (signals non-monotonic in ability). A result of the model is that countersignaling is more expected to occur in jobs that require a combination of skills that differs from the combination used in the schooling process. The model also produces testable implications consistent with evidence on the GED: (i) it signals both high cognitive and low non-cognitive skills and (ii) it does not affect wages. Additionally, it suggests modifications that would make the GED a more effective signal.

Avaliando questionários de risco e o comportamento do investidor sobre a ótica de behavioral finance

Tolerância ao risco é fundamental quando se tomam decisões financeiras. No entanto, a avaliação da tolerância ao risco tem se baseado ao longo dos anos em diferentes metodologias, tais como julgamentos heurísticos e a teoria da utilidade esperada que tem como base a hipótese dos mercados eficientes. Foi dentro desta ótica que este trabalho se desenvolveu. O objetivo é analisar três diferentes questionários de avaliação ao risco que são na prática amplamente utilizados por consultores financeiros. Foi assumido para isso que os investidores são considerados racionais, conhecem e ordenam de forma lógica suas preferências, buscam maximizar a "utilidade" de suas escolhas, e conseguem atribuir com precisão probabilidades aos eventos futuros, quando submetidos a escolhas que envolvam incertezas. No entanto, em uma análise preliminar dos questionários, estes poderiam estar utilizando conceitos de behavioral finance para avaliarem a tolerância ao risco, ao invés de utilizarem somente a metodologia tradicional da teoria da utilidade esperada. Dessa forma tornou-se necessário o estudo dos conceitos de behavioral finance. O primeiro capítulo então trata dos aspectos psicológicos do investidor, procurando entender como este se comporta e como este forma suas preferências. Apesar do estudo assumir racionalidade nas decisões, se a teoria de behavioral estiver correta e os investidores apresentarem desvios a racionalidade, como a teoria prospectiva afirma, o questionário poderia ser o veículo ideal para identificar tais desvios, sendo possível então educar e orientar o indivíduo em suas escolhas financeiras, afim de maximizá-las. O capitulo dois coloca a análise dos questionários inserida no contexto da teoria moderna de finanças, falando das escolhas de portfólio para investidores de longo prazo. O capítulo mostra de forma bem resumida e simplificada como o investidor maximiza a sua utilidade da riqueza. A idéia desse capítulo é entender como alguns julgamentos heurísticos assumidos na prática por consultores financeiros afetam as escolhas de portfólio e em quais condições esses julgamentos heurísticos são verdadeiros. Isso se torna importante pois os questionários mesclam medidas de risco com horizonte de investimentos do investidor. Estes questionários são utilizados para traçar uma política de investimentos completa para o investidor. Para cada perfil de risco encontrado a instituição traça um modelo de alocação de portfólio. O capítulo três trata da avaliação dos questionários em si tendo como base a teoria da utilidade esperada, os conceitos de behaviral finance e as lições tiradas das escolhas de portfólio para investidores de longo prazo.

Inflation and income inequality: a shopping-time aproach: (Forthcoming, Journal of Development Economics)

Our work is based on a simpliÖed heterogenous-agent shoppingtime economy in which economic agents present distinct productivities in the production of the consumption good, and di§erentiated access to transacting assets. The purpose of the model is to investigate whether, by focusing the analysis solely on endogenously determined shopping times, one can generate a positive correlation between ináation and income inequality. Our main result is to show that, provided the productivity of the interest-bearing asset in the transacting technology is high enough, it is true true that a positive link between ináation and income inequality is generated. Our next step is to show, through analysis of the steady-state equations, that our approach can be interpreted as a mirror image of the usual ináation-tax argument for income concentration. An example is o§ered to illustrate the mechanism.

The diversity of diversity: further methodological considerations on the use of the concept in cultural economics

The implications of diversity still raise confusion in the cultural debate. We address them from both a formal and conceptual viewpoints, putting in check the validity of some arguments. We conclude that: measuring diversity demands key decisions and careful statistical procedures; ignorance on optimal diversity levels and on ways to generate them is widespread in the cultural field; there is no support for cultural diversity as something associated to fair economic and political systems; restriction to sheer economics requires the establishment of links between diversity and measurable properties – something rather incipient. Diversity, as a social choice, should be distinguished from it as an economic value.

Essays on international economics

This study in International Economics has three main goals. First, to indicate, among seven price indices, the one with the highest purchasing power parity (PPP) evidence; second, to suggest that the international trade theory explains to satisfaction the real exchange rate parity among countries with similar relative-factor-endowment; and third, to study the impact of the Brazilian trade openness on labor demand elasticity.

The two methods of economics

A Teoria Econômica Emprega Dois Métodos: o Método Hipotético-Dedutivo, Utilizado Principalmente Pelos Economistas Neoclássicos, e o Método Histórico-Dedutivo, Adotado Pelos Economistas Clássicos e Keynesianos. Ambos são Legítimos, Mas, Desde que a Economia é Substantiva, não uma Ciência Metodológica, Onde o Objeto é o Sistema Econômico, o Método Histórico-Dedutivo é o Mais Apropriado. o Método Hipotético-Dedutivo Permite que o Economista Desenvolva Ferramentas para Analisar o Sistema Econômico, Mas Falha ao Analisar o Sistema como um Todo. em Contrapartida, o Método Histórico-Dedutivo Parte da Observação Empírica da Realidade e da Busca por Regularidades e Tendências. é um Método Empírico, Apropriado para as Ciências Substantivas que Tratam de Sistemas Abertos, como é o Caso da Economia.

Pluralism in economics: from epistemology to hermeneutics

The objective of this paper is to bring elements from the philosophical movement of hermeneutics and pragmatism to the discussion on methodology in economics, with a specific concern on the theory of truth. Our aim is to present the concept of the hermeneutic space, developed by the philosopher Richard Rorty, as a rational justification for pluralism in economics. We consider the hermeneutic space an interesting concept which should allow us to overcome the void left by the incapacity of epistemological theories to explain the evolution of sciences. It defends the idea that our culture, values and ways of interpreting things are what build the sciences, not any closed epistemological method. In this sense, pluralism is nothing more than letting the hermeneutic space work, without epistemological barriers, and understanding that this is desirable for the future development of economics as a science. This approach differs from all other methodological justifications for pluralism because it does not rely on any epistemological method, but assumes that the hermeneutic space can entirely fulfill the gap created by them

Assorted topics in monetary economics

Esta tese é uma coleção de quatro artigos em economia monetária escritos sob a supervisão do Professor Rubens Penha Cysne. O primeiro desses artigos calcula o viés presente em medidas do custo de bem-estar da inflação devido a não se levar em conta o potencial substitutivo de moedas que rendem juros, como depósitos bancários.[1] O segundo se concentra na questão teórica de se comparar os escopos dos tradicionais modelos money-in-the-utility-function e shopping-time através do estudo das propriedades das curvas de demanda que eles geram.[2] O terceiro desses trabalhos revisita um artigo clássico de Stanley Fischer sobre a correlação entre a taxa de crescimento da oferta monetária e a taxa de acumulação de capital no caminho de transição.[3] Finalmente, o quarto diz respeito à posição relativa de cada uma de seis medidas do custo de bem-estar da inflação (uma das quais é nova) em relação às outras cinco, e uma estimativa do erro relativo máximo em que o pesquisador pode incorrer devido a sua escolha de empregar uma dessas medidas qualquer vis-à-vis as outras.[4] This thesis collects four papers on monetary economics written under the supervision of Professor Rubens Penha Cysne. The first of these papers assesses the bias occuring in welfare-cost-of-inflation measures due to failing to take into consideration the substitution potential of interest-bearing monies such as bank deposits.[1] The second one tackles the theoretical issue of comparing the generality of the money-in-the-utility-function- and the shopping-time models by studying the properties of the demand curves they generate.[2] The third of these works revisits a classic paper by Stanley Fischer on the correlation between the growth rate of money supply and the rate of capital accumulation on the transition path.[3] Finally, the fourth one concerns the relative standing of each one of six measures of the welfare cost of inflation (one of which is new) with respect to the other five, and an estimate of the maximum relative error one can incur by choosing to employ a particular welfare measure in place of the others.[4] [1] Cysne, R.P., Turchick, D., 2010. Welfare costs of inflation when interest-bearing deposits are disregarded: A calculation of the bias. Journal of Economic Dynamics and Control 34, 1015-1030. [2] Cysne, R.P., Turchick, D., 2009. On the integrability of money-demand functions by the Sidrauski and the shopping-time models. Journal of Banking & Finance 33, 1555-1562. [3] Cysne, R.P., Turchick, D., 2010. Money supply and capital accumulation on the transition path revisited. Journal of Money, Credit and Banking 42, 1173-1184. [4] Cysne, R.P., Turchick, D., 2011. An ordering of measures of the welfare cost of inflation in economies with interest-bearing deposits. Macroeconomic Dynamics, forthcoming.