The evolution and comparative neurobiology of endocannabinoid signalling

CB(1)- and CB(2)-type cannabinoid receptors mediate effects of the endocannabinoids 2-arachidonoylglycerol (2-AG) and anandamide in mammals. In canonical endocannabinoid-mediated synaptic plasticity, 2-AG is generated postsynaptically by diacylglycerol lipase alpha and acts via presynaptic CB(1)-type cannabinoid receptors to inhibit neurotransmitter release. Electrophysiological studies on lampreys indicate that this retrograde signalling mechanism occurs throughout the vertebrates, whereas system-level studies point to conserved roles for endocannabinoid signalling in neural mechanisms of learning and control of locomotor activity and feeding. CB(1)/CB(2)-type receptors originated in a common ancestor of extant chordates, and in the sea squirt Ciona intestinalis a CB(1)/CB(2)-type receptor is targeted to axons, indicative of an ancient role for cannabinoid receptors as axonal regulators of neuronal signalling. Although CB(1)/CB(2)-type receptors are unique to chordates, enzymes involved in biosynthesis/inactivation of endocannabinoids occur throughout the animal kingdom. Accordingly, non-CB(1)/CB(2)-mediated mechanisms of endocannabinoid signalling have been postulated. For example, there is evidence that 2-AG mediates retrograde signalling at synapses in the nervous system of the leech Hirudo medicinalis by activating presynaptic transient receptor potential vanilloid-type ion channels. Thus, postsynaptic synthesis of 2-AG or anandamide may be a phylogenetically widespread phenomenon, and a variety of proteins may have evolved as presynaptic (or postsynaptic) receptors for endocannabinoids

Dividend and Share Changes: Is There a Financing Hierarchy?

The most widely accepted empirical dividend model is that proposed by Lintner, who argued that firms smooth dividends over time. Many theoretical dividend models, however, either predict that dividends should be highly variable, or at least offer no support for the smoothing hypothesis. We use a switching regression model to test the Lintner model against an alternative which allows dividend behavior to differ depending upon whether or not firms are issuing shares. We reject the Lintner model, finding no evidence of dividend smoothing when firms are not issuing shares, and a high negative dividend growth rate when firms are issuing shares. This description of dividend behavior suggests the existence of a financing hierarchy in that the marginal source of finance differs over time. To further explore the financing hierarchy, we estimate logit models which explain the decisions by firms to change dividends, and to issue or repurchase shares. The results are consistent with the existence of a financing hierarchy.

Inflation Target Transparency and the Macroeconomy

We quantify the effects of monetary policy transparency and credibility on macroeconomic volatility in an estimated model of the euro area economy. In our model, private agents are unable to distinguish between temporary shocks to the central bank’s monetary policy rule and persistent shifts in the inflation target, and therefore use optimal filtering techniques to construct estimates of the future monetary policy stance. We find that the macroeconomic benefits of credibly announcing the current level of the time-varying inflation target are reasonably small as long as private agents correctly understand the stochastic processes governing the inflation target and the temporary policy shock. If, on the other hand, private agents overestimate the volatility of the inflation target, the overall gains of announcing the target can be substantial. We also show that the central bank to some extent can help private agents in their learning process by responding more aggressively to deviations of inflation from the target.Credibility; Transparency; Inflation targeting; Imperfect information; Private sector learning

Emerging Threats to Human Rights: Resources, Violence, and Deprivation of Citizenship, edited by Heather Smith-Cannoy

Emerging Threats to Human Rights: Resources, Violence, and Deprivation of Citizenship, edited by Heather Smith-Cannoy. Philadelphia: Temple University Press, 2019. 288 pages. ISBN-10: 1439917191; ISBN-13: 978-1439917190. RRP: A$93.00, paperback. Reviewed by Kelly Soderstrom, University of Melbourne, Melbourne, Australia

If Teachers “Were Congressmen:” A Satire

A satirical article imagining if academics worked like United States politics

Cannabinoid exposure during zebra finch sensorimotor vocal learning persistently alters expression of endocannabinoid signaling elements and acute agonist responsiveness

<p>Abstract</p> <p>Background</p> <p>Previously we have found that cannabinoid treatment of zebra finches during sensorimotor stages of vocal development alters song patterns produced in adulthood. Such persistently altered behavior must be attributable to changes in physiological substrates responsible for song. We are currently working to identify the nature of such physiological changes, and to understand how they contribute to altered vocal learning. One possibility is that developmental agonist exposure results in altered expression of elements of endocannabinoid signaling systems. To test this hypothesis we have studied effects of the potent cannabinoid receptor agonist WIN55212-2 (WIN) on endocannabinoid levels and densities of CB₁immunostaining in zebra finch brain.</p> <p>Results</p> <p>We found that late postnatal WIN treatment caused a long-term global disregulation of both levels of the endocannabinoid, 2-arachidonyl glycerol (2-AG) and densities of CB₁immunostaining across brain regions, while repeated cannabinoid treatment in adults produced few long-term changes in the endogenous cannabinoid system.</p> <p>Conclusions</p> <p>Our findings indicate that the zebra finch endocannabinoid system is particularly sensitive to exogenous agonist exposure during the critical period of song learning and provide insight into susceptible brain areas.</p

Evolution of the Grasses x)

Because the flowers of grassos are so reduced, botanists in past have relied mostly on vegetative characters, such as the spikelets and their disposition in the inflorescence,to classify the family.Hackel,in his treatment of the Gramineae in Die Naturlichen pflanzen familien (late 1800'S proposed 12 tribes based on these characteristies and regarded the tribe