Journal of neuroendocrinology
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J. Neuroendocrinol. · May 2015
Masculinisation of the zebra finch song system: roles of oestradiol and the Z-chromosome gene tubulin-specific chaperone protein A.
Robust sex differences in brain and behaviour exist in zebra finches. Only males sing, and forebrain song control regions are more developed in males. The factors driving these differences are not clear, although numerous experiments have shown that oestradiol (E2 ) administered to female hatchlings partially masculinises brain and behaviour. ⋯ TBCA siRNA delivered to the LMAN also decreased the projection from this brain region to the RA, as indicated by anterograde tract tracing. The results suggest that TBCA is involved in masculinising the song system. However, because no interactions between the siRNA and hormone manipulations were detected, TBCA does not appear to modulate effects of E2 in the zebra finch song circuit.
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J. Neuroendocrinol. · Jan 2015
Role of AMP-activated protein kinase activators in antiproliferative multi-drug pituitary tumour therapies: effects of combined treatments with compounds affecting the mTOR-p70S6 kinase axis in cultured pituitary tumour cells.
AMP-activated protein kinase (AMPK) is activated under conditions that deplete cellular ATP levels and elevate AMP levels. We have recently shown that AMPK can represent a valid target for improving the medical treatment of growth hormone (GH)-secreting pituitary adenomas and the effects of its activation or inhibition in pituitary tumour cells are worthy of further characterisation. We aimed to determine whether AMPK may have a role in combined antiproliferative therapies based on multiple drugs targeting cell anabolic functions at different levels in pituitary tumour cells to overcome the risk of cell growth escape phenomena. ⋯ AICAR induced apoptosis of GH3 cells, whereas rapamycin caused preferentially a decrease of cell proliferation. Finally, AICAR and rapamycin differed in their actions on growth factor-induced extracellular signal regulated kinase 1/2 phosphorylation. In conclusion, the results of the present study suggest the increased efficacy of combined antiproliferative therapies, including rapamycin analogues and AMPK activators in GH-secreting pituitary tumours, as a result of complementary and only partially overlapping mechanisms of action.
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J. Neuroendocrinol. · Dec 2014
Modifications of glucocorticoid receptors mRNA expression in the hypothalamic-pituitary-adrenal axis in response to early-life stress in female Japanese quail.
Stress exposure during early-life development can programme individual brain and physiology. The hypothalamic-pituitary-adrenal (HPA) axis is one of the primary targets of this programming, which is generally associated with a hyperactive HPA axis, indicative of a reduced negative-feedback. This reduced feedback efficiency usually results from a reduced level of the glucocorticoid receptor (GR) and/or the mineralocorticoid receptor (MR) within the HPA axis. ⋯ Both early-life treatments permanently affected the expression of both receptor types in HPA axis regions. The effects of prenatal stress are in accordance with a more efficient negative-feedback within the HPA axis and thus can explain the attenuated stress response observed in these birds. Therefore, these changes in receptor density or number as a consequence of early-life stress exposure might be the mechanism that allows an adaptive response to later-life stressful conditions.
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J. Neuroendocrinol. · Aug 2014
Divergent neuronal circuitries underlying acute orexigenic effects of peripheral or central ghrelin: critical role of brain accessibility.
Ghrelin is an octanoylated peptide hormone that potently and rapidly increases food intake. The orexigenic action of ghrelin involves the hypothalamic arcuate nucleus (ARC), which is accessible to plasma ghrelin and expresses high levels of the ghrelin receptor. Local administration of ghrelin in a variety of other brain nuclei also increases food intake. ⋯ ARC-ablated mice showed patterns of ghrelin-induced c-Fos expression similar to those seen in control mice with the exception of the ARC, where no c-Fos was found. Thus, peripheral ghrelin mainly accesses the ARC, which is required for the orexigenic effects of the hormone. Central ghrelin accesses a variety of nuclei, which can mediate the orexigenic effects of the hormone, even in the absence of an intact ARC.
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J. Neuroendocrinol. · May 2014
Oestradiol modulation of cognition in adult female marmosets (Callithrix jacchus).
The common marmoset (Callithrix jacchus) provides many advantages over traditional rodent and macaque species as a model for human ageing and may be very useful for studying the effects of sex steroids on cognitive and brain ageing. We present the first study examining the effects of oestrogens on cognitive function in female marmosets. Adult monkeys (3-5 years of age) were trained to a specific learning criterion on a battery of cognitive tasks preoperatively (object discrimination, delayed response with increasing delays and detour reaching with opaque box) and were tested on different versions of these tasks (object reversals, delayed response with randomised delays and detour reaching with clear box) after ovariectomy and simultaneous implantation with 17β-oestradiol (E2 ) (n = 6) or blank (n = 6) Silastic capsules. ⋯ The suggestion that E2 may improve acquisition on tasks dependent on the hippocampus will require further validation. These results are discussed in the context of dopaminergic and serotonergic signalling. We conclude that the marmoset is a useful new primate model for examining the effects of oestrogens on cognitive function.