2 research outputs found
Role for the M<sub>1</sub> Muscarinic Acetylcholine Receptor in Top-Down Cognitive Processing Using a Touchscreen Visual Discrimination Task in Mice
The M<sub>1</sub> muscarinic acetylcholine
receptor (mAChR) subtype
has been implicated in the underlying mechanisms of learning and memory
and represents an important potential pharmacotherapeutic target for
the cognitive impairments observed in neuropsychiatric disorders such
as schizophrenia. Patients with schizophrenia show impairments in
top-down processing involving conflict between sensory-driven and
goal-oriented processes that can be modeled in preclinical studies
using touchscreen-based cognition tasks. The present studies used
a touchscreen visual pairwise discrimination task in which mice discriminated
between a less salient and a more salient stimulus to assess the influence
of the M<sub>1</sub> mAChR on top-down processing. M<sub>1</sub> mAChR
knockout (M<sub>1</sub> KO) mice showed a slower rate of learning,
evidenced by slower increases in accuracy over 12 consecutive days,
and required more days to acquire (achieve 80% accuracy) this discrimination
task compared to wild-type mice. In addition, the M<sub>1</sub> positive
allosteric modulator BQCA enhanced the rate of learning this discrimination
in wild-type, but not in M<sub>1</sub> KO, mice when BQCA was administered
daily prior to testing over 12 consecutive days. Importantly, in discriminations
between stimuli of equal salience, M<sub>1</sub> KO mice did not show
impaired acquisition and BQCA did not affect the rate of learning
or acquisition in wild-type mice. These studies are the first to demonstrate
performance deficits in M<sub>1</sub> KO mice using touchscreen cognitive
assessments and enhanced rate of learning and acquisition in wild-type
mice through M<sub>1</sub> mAChR potentiation when the touchscreen
discrimination task involves top-down processing. Taken together,
these findings provide further support for M<sub>1</sub> potentiation
as a potential treatment for the cognitive symptoms associated with
schizophrenia
Rare and low-frequency coding variants alter human adult heigh
Height is a highly heritable, classic polygenic trait with approximately 700 common associated variants identified through genome-wide association studies so far. Here, we report 83 height-associated coding variants with lower minor-allele frequencies (in the range of 0.1-4.8%) and effects of up to 2 centimetres per allele (such as those in IHH, STC2, AR and CRISPLD2), greater than ten times the average effect of common variants. In functional follow-up studies, rare height-increasing alleles of STC2 (giving an increase of 1-2 centimetres per allele) compromised proteolytic inhibition of PAPP-A and increased cleavage of IGFBP-4 in vitro, resulting in higher bioavailability of insulin-like growth factors. These 83 height-associated variants overlap genes that are mutated in monogenic growth disorders and highlight new biological candidates (such as ADAMTS3, IL11RA and NOX4) and pathways (such as proteoglycan and glycosaminoglycan synthesis) involved in growth. Our results demonstrate that sufficiently large sample sizes can uncover rare and low-frequency variants of moderate-to-large effect associated with polygenic human phenotypes, and that these variants implicate relevant genes and pathways