It is established that in songbirds the size of several brain song control nuclei varies seasonally, based on changes in cell size, dendritic branching and, in nucleus HVC, the incorporation of newborn neurons. In the developing and adult mammalian brain, the protein doublecortin (DCX) is expressed in postmitotic neurons and, as a part of the microtubule machinery, required for neuronal migration. We recently showed that in adult canaries, DCX-immunoreactive (ir) cells are present throughout the telencephalon, but the link between DCX and the active neurogenesis observed in songbirds remained uncertain. We demonstrate here that DCX labels recently born cells in the canary telencephalon and that, in parallel with changes in HVC volume, the number of DCX-ir cells is increased specifically in the HVC of testosterone-treated males compared with castrates, and in castrated testosterone-treated males paired with a female as compared with males paired with another male. The numbers of elongated DCX-ir cells (presumptive migrating neurons) and round multipolar DCX-ir cells (differentiating neurons) were also affected by the sex of the subjects and their photoperiodic condition (photosensitive vs photostimulated vs photorefractory). Thus, in canaries the endocrine state, as well as the social or photoperiodic condition independently of variation in steroid hormone action, affects the number of cells expressing a protein involved in neuronal migration specifically in brain areas that incorporate new neurons in the telencephalon. The DCX gene may be one of the targets by which testosterone and social stimuli induce seasonal changes in the volume of song nuclei.

Neurodegeneration and depression are two common co-morbid conditions, particularly within the aging population. Research has linked neuroinflammation as a major contributing factor to both of these diseases. The key to neuroinflammation effects on neurodegeneration and depression appears to lie within the dysregulation of the control and release of pro- and anti-inflammatory cytokines. This can come from an internal or external insult to the system, or from changes in the individual due to aging that culminate in immune dysregulation. The need to reduce neuroinflammation has led to extensive research into neuroprotectants. We discuss the efficacy found with nicotine, alcohol, resveratrol, curcumin, and ketamine. Our main focus will be on what research is telling us about the connections between neuroinflammation, neurodegeneration, and depression, and the hope that neuroprotectants research is giving people suffering from neurodegeneration and depression stemming from neuroinflammation. We will conclude by making suggestions for future research in this area.

Supplementary information: 4 tables, 6 figuresSupplementary materials: Two Excel files for GWAS, eQTL and eigenGWAS, and summary of gene expression analysis. One .mpg file that contains videos of motile sperm of alternative karyomorphs. 2Sperm competition is an important selective force in many organisms. As a result, sperm have evolved to be among the most diverse cells in the animal kingdom. However, the relationship between sperm morphology, sperm motility and fertilisation success is only partially understood. The extent to which between-male variation is heritable is largely unknown, and remarkably few studies have investigated the genetic architecture of sperm traits, especially sperm morphology. Here we use high-density genotyping and gene expression profiling to explore the considerable sperm trait variation that exists in the zebra finch Taeniopygia guttata.We show that nearly all of the genetic variation in sperm morphology is caused by an inversion polymorphism on the Z chromosome acting as a 'supergene'. These results provide a striking example of two evolutionary genetic predictions. First, that in species where females are the heterogametic sex, genetic variation affecting sexually dimorphic traits will accumulate on the Z chromosome. Second, recombination suppression at the inversion allows beneficial dominant alleles to become fixed on whichever haplotype they first arise, without being exchanged onto other haplotypes. Finally, we show that the inversion polymorphism will be stably maintained by heterozygote advantage, because heterozygous males have the fastest and most successful sperm.Sperm are perhaps the most diverse cells in the animal kingdom, with enormous morphological variation between taxa, between species, between males and within an ejaculate 1 .Considerable interest in sperm diversity has arisen following the realisation that sperm competition (post-copulatory sexual selection) is a powerful selective force in many organisms 2 , and that sperm morphology has co-evolved with female reproductive tract morphology 3 . The zebra finch is a model species for studies of sperm biology. Sperm length is repeatable within an ejaculate, yet variable between different males; most morphological traits (head, midpiece, tail and total length) are highly heritable 4 . Furthermore, there is a documented phenotypic and genetic correlation between morphology and sperm swimming velocity ('motility') 5 . In artificially selected lines, pronounced differences in total sperm length are apparent after just three generations of divergent selection, and males with long sperm have the greatest probability of fertilisation success in sperm competition 3 trials 6 . Additionally, the zebra finch has its genome sequenced, assembled and annotated 7 , and so the toolkit to explore the genetics of phenotypic variation is available.In this study we set out to understand the genetic architecture of sperm morphology and motility in the zebra finch. Our aim was to combine genome wide association mapping with analyses of ...

Resveratrol (3,4’,5-trihydroxy-trans-stilbene) is a natural non-flavonoid polyphenol antioxidant extracted from red grapes in the processing of wine. Initially it was studied for its potential as anticancer drug, and later was found to reduce cardiovascular disease. More recently resveratrol was shown to alleviate depressive-like symptoms induced by stress or other means in mice and rats. The major purpose of this study was to investigate whether resveratrol would manifest an antidepressant effect in Wistar-Kyoto (WKY) rats, a putative and non-induced animal model of depression, and whether this effect might be associated with an increase in hippocampal and frontal cortical brain-derived neurotrophic factor (BDNF), a protein implicated in chronic effects of many antidepressants. Adult male WKY rats were injected with two doses of resveratrol (10 and 40 mg/kg, i.p.) and their behavior in the open field locomotor activity (LMA), forced swim test (FST: a measure of helplessness), and sucrose preference test (SPT: a measure of anhedonia) was evaluated after a single acute injection or following 7 days of daily treatment. Both acute and chronic administration of resveratrol resulted in a dose-dependent decrease in FST. However, only chronic resveratrol resulted in dose-dependent increase in sucrose consumption. LMA was not affected by any treatment. Parallel to the observed behavioral effects the level of hippocampal, but not frontal cortical, BDNF was also dose-dependently elevated after chronic resveratrol administration. These findings indicate an antidepressant-like effect of resveratrol in an animal model of depression possibly via activation of hippocampal BDNF, and suggest therapeutic potential of resveratrol in at least a subpopulation of depressed patients.

For sexually reproducing species, functionally competent sperm are critical to reproduction. While high atmospheric temperatures are known to influence the timing of breeding, incubation and reproductive success in birds, the effect of temperature on sperm quality remains largely unexplored. Here, we experimentally investigated the impact of ecologically relevant extreme temperatures on cloacal temperature and sperm morphology and motility in zebra finches We periodically sampled males exposed to 30°C or 40°C temperatures daily for 14 consecutive days. Following a 12-day (23°C) recovery period, birds were again exposed to heat, but under the alternate treatment (e.g. birds initially exposed to 40°C were exposed to 30°C). Elevated temperatures led to an increase in cloacal temperature and a reduction in the proportion of sperm with normal morphology; these effects were most notable under 40°C conditions, and were influenced by the duration of heat exposure and prior exposure to high temperature. Our findings highlight the potential role of temperature in determining male fertility in birds, and perhaps also in constraining the timing of avian breeding. Given the increased frequency of heatwaves in a warming world, our results suggest the need for further work on climatic influences on sperm quality and male fertility.

The most commonly documented morphological response across many taxa to climatic variation across their range follows Bergmann's rule, which predicts larger body size in colder climates. In observational data from wild zebra finches breeding across a range of temperatures in the spring and summer, we show that this relationship appears to be driven by the negative effect of high temperatures during development. This idea was then experimentally tested on zebra finches breeding in temperature-controlled climates in the laboratory. These experiments confirmed that those individualso produced in a hot environment (30 °C) were smaller than those produced in cool conditions (18 °C). Our results suggest a proximate causal link between temperature and body size and suggest that a hotter climate during breeding periods could drive significant changes in morphology within and between populations. This effect could account for much of the variation in body size that drives the well-observed patterns first described by Bergmann and that is still largely attributed to selection on adult body size during cold winters. The climate-dependent developmental plasticity that we have demonstrated is an important component in understanding how endotherms may be affected by climate change.

Curcumin is the principal active ingredient found in turmeric (Curcuma longa), a plant used in traditional Asian diets and herbal medicines. It is known to have a wide range of biological actions including antidepressant-like effects which have been observed in stress-induced depression models. This study was designed to investigate the antidepressant potential of curcumin in a non-induced model of depression. Moreover, since brain derived neurotrophic factor (BDNF) has been implicated in antidepressant effects of many drugs, we also evaluated the effects of curcumin on BDNF in the hippocampus. Adult male Wistar Kyoto (WKY) rats, a putative model of depression, were injected acutely or chronically (10 d) with 50, 100, and 200mg/kg curcumin. Open field locomotor activity (OFLA) and forced swim test (FST), a measure of helplessness, were measured 1 hour after acute and 18–20 hours after last chronic injection. Results showed a dose-dependent reduction of immobility in the FST by curcumin in both acute and chronic studies, without any significant effect on OFLA. The effect of higher chronic curcumin dose in FST was still evident a week later. Chronic curcumin also resulted in a dose-dependent increase in hippocampal BDNF. This data provides evidence for an antidepressant-like effect of curcumin, possibly through increased neurotrophic activity, in the WKY model of depression, and support the notion that curcumin may prove an effective and lasting natural antidepressant.

The acute stress response involves the secretion of catabolic glucocorticoids, such as corticosterone (CORT) in birds, that mobilize intrinsic energy stores primarily through a gluconeogenic pathway involving fat breakdown, thus linking body condition and stress. We measured changes in CORT and gluconeogenic metabolites (triglycerides, free glycerols, glucose) during handling stress in curve-billed thrashers Toxostoma curvirostre from two habitats (urban vs. desert) that may differ in food abundance in the wild, in captivity, and in response to both food restriction and subsequent recovery. Urban thrashers were heavier and secreted more CORT than desert birds in the field, but differences did not persist in captivity. Decreased access to food resulted in decreased body mass and a diminished ability to elevate plasma CORT in response to handling stress. However, the opposite effect was observed as these birds recovered from food restriction. Plasma levels of glucose and triglycerides did not change with stress. Food restriction also increased locomotor activity, which likely further exacerbated energy loss. These observations suggest that body condition and stress differences between urban and desert birds may be related to differences in their relative energetic states, possibly due to food availability. Body condition may affect the extent to which an individual can elevate CORT and use free glycerol as energy during acute stress.