Foraging along a salinity gradient:The effect of tidal inundation on site choice by Dark-Bellied Brent Geese <i>Branta bernicla</i> and Barnacle Geese <i>B. leucopsis</i>

We report on the effects of salt deposition on food plants on the foraging preferences of Dark-bellied Brent Branta bernicla and Barnacle Geese B. leucopsis in a coastal staging habitat. Within one salt-marsh plant community, dominated by Red Fescue Festuca rubra, grazing pressure by geese increased with elevation (related to mean high tide), although both standing crop and nitrogen content of the forage were highest at plots lower on the salt marsh. Salt deposition on Festuca leaves decreased with increasing surface height along the elevational gradient. The, matching of census data for three spring seasons and data on soil surface elevation revealed that flocks of Barnacle Geese forage, on average, 0.4 m higher on the salt marsh than sympatric Dark-bellied Brent Geese. 84% of the Barnacle Goose flocks were encountered in areas characterised by an inundation frequency of less than 20 during the period from February through April, whereas this applied to only 44% of the Dark-bellied Brent Goose flocks. Barnacle Geese avoided foraging on salt-marsh vegetation experimentally sprayed with seawater, showing a significant preference for untreated control plots, whereas Dark-bellied Brent Geese did not react to the treatment. Dissection of nasal glands in carcasses of both species revealed that the metabolic mass-specific weight of the nasal glands of Dark-bellied Brent Geese exceeded that of Barnacle Geese by nearly a factor four. Within this species-pair of Dark-bellied Brent and Barnacle Geese, jointly using salt-marsh staging sites in spring, Barnacle Geese appear to be physiologically constrained in their choice of foraging sites within the salinity gradient of their habitat.</p

ROLE OF 5-HT2C RECEPTORS IN DYSKINESIA

By integrating knowledge gained by pharmacogenetic, neuroanatomical and pharmacological studies, a model can be constructed how serotonin (5-HT) affects the vulnerability to induce tardive dyskinesia. From neuroanatomical studies, it can be concluded that 5-HT inhibits the release of dopamine (DA) within the dorsal striatum by affecting 5-HT2C receptors and also within the ventral striatum and prefrontal cortex by affecting 5-HT2A receptors. However, considering the low affinity of DA for its receptors, it is unlikely that the so released DA is able to displace atypical antipsychotics from DA D2 and D3 receptors. 5-HT2C receptors and, to a lesser extent, 5-HT2A receptors, have constitutive activity and therefore, atypical antipsychotics can have inverse agonistic effects. It is hypothesized that decreasing the activity of 5-HT2 receptor carrying medium spiny neurons (MSNs) within the dorsal striatum represents the mechanism showing how atypical antipsychotics have limited ability to cause tardive dyskinesia.Â

Putative role of vitamin D in the mechanism of alcoholism and other addictions - a hypothesis

OBJECTIVE: Vitamin D deficiency may be a clinical problem in patients with addictions. The authors systematically searched for studies addressing vitamin D and addiction and develop a hypothesis which can direct future research of the possible mechanistic role of vitamin D in the process of addiction. METHODS: Systematic review of the literature found in PubMed and EMBASE followed by narrative review combined with clinical experiences leading to hypotheses for future research. RESULTS: Only five articles were identified about a role of vitamin D in the pathophysiology of addiction. Their results are in line with a possible influence of vitamin D in dopaminergic transmission. The cerebral vitamin D status depends on the functionality of genetic variants of vitamin D receptor and other involved genes. Routine serum calcidiol levels may not adequately reflect cerebral vitamin D status. Uncertainty exists regarding appropriate calcidiol blood levels and proper dosages for affecting the central nervous system (CNS). CONCLUSIONS: The putative pathophysiological role of vitamin D in substance abuse has been insufficiently studied which calls to more studies how to measure cerebral vitamin D status in clinical practice. Research is indicated whether vitamin D supplementation should use higher dosages and aim to reach higher calcidiol serum levels. Measuring dopaminergic functioning within the prefrontal cortex as reflected by neuropsychological tests selected as suitable could be a appropriate proxy for the cerebral vitamin D status when studying the pharmacogenomics of this functionality in patients

Role OF 5-HT2C receptors in dyskinesia

By integrating knowledge gained by pharmacogenetic, neuroanatomical and pharmacological studies, a model can be constructed how serotonin (5-HT) affects the vulnerability to induce tardive dyskinesia. From neuroanatomical studies, it can be concluded that 5-HT inhibits the release of dopamine (DA) within the dorsal striatum by affecting 5-HT2C receptors and also within the ventral striatum and prefrontal cortex by affecting 5-HT2A receptors. However, considering the low affinity of DA for its receptors, it is unlikely that the so released DA is able to displace atypical antipsychotics from DA D2 and D3 receptors. 5-HT2C receptors and, to a lesser extent, 5-HT2A receptors, have constitutive activity and therefore, atypical antipsychotics can have inverse agonistic effects. It is hypothesized that decreasing the activity of 5-HT2 receptor carrying medium spiny neurons (MSNs) within the dorsal striatum represents the mechanism showing how atypical antipsychotics have limited ability to cause tardive dyskinesia