Acetylcholine (ACh) is an important neuromodulator in the nervous system implicated in many forms of cognitive and motor processing. Recent studies have used bacterial artificial chromosome (BAC) transgenic mice expressing channelrhodopsin-2 (ChR2) protein under the control of the choline acetyltransferase (ChAT) promoter (ChAT-ChR2-EYFP) to dissect cholinergic circuit connectivity and function using optogenetic approaches. We report that a mouse line used for this purpose also carries several copies of the vesicular acetylcholine transporter gene (VAChT), which leads to overexpression of functional VAChT and consequently increased cholinergic tone. We demonstrate that these mice have marked improvement in motor endurance. However, they also present severe cognitive deficits, including attention deficits and dysfunction in working memory and spatial memory. These results suggest that increased VAChT expression may disrupt critical steps in information processing. Our studies demonstrate that ChAT-ChR2-EYFP mice show altered cholinergic tone that fundamentally differentiates them from wild-type mice.

A novel mouse model that eliminates cholinergic neurotransmission in the striatum while leaving glutamate release intact reveals differential effects on cocaine-induced behavior and dopaminergic responses.

Stanniocalcin (STC)-2 was discovered by its primary amino acid sequence identity to the hormone STC-1. The function of STC-2 has not been examined; thus we generated two lines of transgenic mice overexpressing human (h)STC-2 to gain insight into its potential functions through identification of overt phenotypes. Analysis of mouse Stc2 gene expression indicates that, unlike Stc1, it is not highly expressed during development but exhibits overlapping expression with Stc1 in adult mice, with heart and skeletal muscle exhibiting highest steady-state levels of Stc2 mRNA. Constitutive overexpression of hSTC-2 resulted in pre-and postnatal growth restriction as early as embryonic day 12.5, progressing such that mature hSTC-2-transgenic mice are ϳ45% smaller than wild-type littermates. hSTC-2 overexpression is sometimes lethal; we observed 26 -34% neonatal morbidity without obvious dysmorphology. hSTC-2-induced growth retardation is associated with developmental delay, most notably cranial suture formation. Organ allometry studies show that hSTC-2-induced dwarfism is associated with testicular organomegaly and a significant reduction in skeletal muscle mass likely contributing to the dwarf phenotype. hSTC-2-transgenic mice are also hyperphagic, but this does not result in obesity. Serum Ca 2ϩ and PO4 were unchanged in hSTC-2-transgenic mice, although STC-1 can regulate intra-and extracellular Ca 2ϩ in mammals. Interestingly, severe growth retardation induced by hSTC-2 is not associated with a decrease in GH or IGF expression. Consequently, similar to STC-1, STC-2 can act as a potent growth inhibitor and reduce intramembranous and endochondral bone development and skeletal muscle growth, implying that these tissues are specific physiological targets of stanniocalcins.stanniocalcins; stanniocalcin-related protein; development STANNIOCALCINS REPRESENT a small family of secreted homodimeric glycoprotein hormones consisting of STC-1 and STC-2, also known as stanniocalcin-related protein (STCrP), that has been conserved from aquatic to terrestrial vertebrates. STC-1 and STC-2 do not show significant homology to any other known proteins, and this has hampered understanding of their function(s). Initially, it was assumed that mammalian STC-1 would mimic the function of fish STC-1 in mineral homeostasis, and there is evidence to support this (26, 37, 52). Recently, however, it has become clear that STC-1 has a significantly expanded role in mammals on the basis of its expression pattern (7), gain-of-function transgenic mouse studies (13, 49), and subcellular localization (29, 38).STC-2 was initially identified as a stanniocalcin by virtue of its 50% identity and 73% amino acid homology to a stretch of 76 amino acids located between positions 24 and 101 of human (h)STC-1 (8, 12, 18, 32). hSTC-2 amino acid sequence downstream of position 101 shows less identity (23%) to hSTC-1, and it is 45 amino acids larger even though the genes encoding these proteins have identical intron/exon junctions (18). Unlike with STC-1, studies examini...

Basal forebrain cholinergic neurons, which innervate the hippocampus and cortex, have been implicated in many forms of cognitive function. Immunolesion-based methods in animal models have been widely used to study the role of acetylcholine (ACh) neurotransmission in these processes, with variable results. Cholinergic neurons have been shown to release both glutamate and ACh, making it difficult to deduce the specific contribution of each neurotransmitter on cognition when neurons are eliminated. Understanding the precise roles of ACh in learning and memory is critical because drugs that preserve ACh are used as treatment for cognitive deficits. It is therefore important to define which cholinergic-dependent behaviors could be improved pharmacologically. Here we investigate the contributions of forebrain ACh on hippocampal synaptic plasticity and cognitive behavior by selective elimination of the vesicular ACh transporter, which interferes with synaptic storage and release of ACh. We show that elimination of vesicular ACh transporter in the hippocampus results in deficits in long-term potentiation and causes selective deficits in spatial memory. Moreover, decreased cholinergic tone in the forebrain is linked to hyperactivity, without changes in anxiety or depression-related behavior. These data uncover the specific contribution of forebrain cholinergic tone for synaptic plasticity and behavior. Moreover, these experiments define specific cognitive functions that could be targeted by cholinergic replacement therapy.Alzheimer's disease | Morris water maze | synaptic vesicle | Barnes maze T he mechanisms that underlie the formation of hippocampaldependent spatial memory have been broadly explored (1). However, the neurochemical basis underlying changes in the strength of synaptic connections necessary for memories to persist is still not precisely understood. In the case of the hippocampus, mechanisms for memory processing include mRNA-dependent (2) and mammalian target of rapamycin (mTOR)-mediated protein synthesis (3) as well as a sequence of biochemical events shared with or closely similar to that of long-term potentiation (LTP) (2). Indeed, the consolidation of two different aversive tasks (4) and of spatial recognition memory (5) is accompanied by LTP of the CA3-CA1 synapse and can be occluded by a preceding LTP.The basal forebrain cholinergic system, which innervates the hippocampus and cortex, has been suggested to modulate LTP in the hippocampus (6-9) and has been implicated in many forms of behavior (10). In addition, spatial memory has also been suggested to depend on cholinergic activity (10), although there are numerous controversies surrounding which behaviors acetylcholine (ACh) regulates (11, 12). Moreover, in few studies cholinergic denervation did not affect expression of LTP (13). Understanding the precise roles of ACh in learning and memory is of importance because in different types of dementia cholinergic function is decreased (14), and manipulations that boost ACh levels at synapses are used a...

Stanniocalcin 1 (STC1) and STC2 are secreted, homodimeric glycoproteins that share 30% amino acid sequence identity. Breast tumour gene profiling studies have demonstrated significantly upregulated STC2 expression in hormoneresponsive positive breast tumours; therefore, the purpose of this study was to investigate STC2 hormonal regulation and function in breast cancer cells. Here we report that STC2 is expressed in a number of human breast cancer cell lines, regardless of their oestrogen (E 2 ) and progesterone (P4) receptor status, and its expression is readily detectable in human and mouse mammary gland tumours. Besides E 2 , retinoic acid (RA) and P4 play an important role in the regulation of STC2 expression, not only in MCF-7 but also in other breast cancer and non-breast cell lines. The expression of the related hormone, STC1, is not affected by the above hormones in breast and endometrial cancer cell lines implying a fundamental difference in regulation in cancer cell lines. The induction of STC2 expression by E 2 and RA occurs at the transcriptional level but through intermediary transcription factors. The STC2 proximal promoter region is not responsible for hormonal induction, but exhibits a high basal transcriptional activity. Constitutive STC2 expression in human breast cancer cell lines resulted in significant impairment of cell growth, migration and cell viability after serum withdrawal. In conclusion, STC2 is a downstream target of E 2 , P4 and RA signalling pathways. In hormone receptor negative cell lines it can function in a paracrine/autocrine fashion to reduce cell proliferation.