Neuropeptide Y receptor Y8b(npy8br)regulates feeding and digestion in Japanese medaka(Oryzias latipes)larvae:evidence from gene knockout

Neuropeptide Y receptor Y8(NPY8R)is a fish-specific receptor with two subtypes,NPY8AR and NPY8BR.Changes in expression levels during physiological processes or in vivo regulation after ventricular injection suggest that NPY8BR plays an important role in feeding regulation;this has been found in only a few fish,at present.In order to better understand the physiological function of npy8br,especially in digestion,we used clustered regularly interspaced short palindromic repeats(CRISPR)/CRISPR-associated protein 9(Cas9)technology to generate npy8br-/-japanese medaka(Oryzias latipes).We found that the deletion of npy8br in medaka larvae affected their feeding and digestion ability,ultimately affecting their growth.Specifically,npy8br deficiency in medaka larvae resulted in decreased feed intake and decreased expression levels of orexigenic genes(npy and agrp).npy8br-/-medaka larvae fed for 10 d(10th day of feeding)still had incompletely digested brine shrimp(Artemia nauplii)in the digestive tract 8 h after feeding,the messenger RNA(mRNA)expression levels of digestion-related genes(amy,lpl,ctra,and ctrb)were significantly decreased,and the activity of amylase,trypsin,and lipase also significantly decreased.The deletion of npy8br in medaka larvae inhibited the growth and significantly decreased the expression of growth-related genes(gh and igf1).Hematoxylin and eosin(H&E)sections of intestinal tissue showed that npy8br-/-medaka larvae had damaged intestine,thinned intestinal wall,and shortened intestinal villi.So far,this is the first npy8br gene knockout model established in fish and the first demonstration that npy8br plays an important role in digestion.

Npy deletion in an alcohol non-preferring rat model elicits differential effects on alcohol consumption and body weight

Neuropeptide Y（NPY） is widely expressed in the central nervous system and influences many physiological processes.It is located within the rat quantitative trait locus（QTL） for alcohol preference on chromosome 4.Alcohol-nonpreferring（NP） rats consume very little alcohol,but have significantly higher NPY expression in the brain than alcohol-preferring（P） rats.We capitalized on this phenotypic difference by creating an Npy knockout（KO） rat using the inbred NP background to evaluate NPY effects on alcohol consumption.Zinc finger nuclease（ZNF） technology was applied,resulting in a 26-bp deletion in the Npy gene.RT-PCR,Western blotting and immunohistochemistry confirmed the absence of Npy mRNA and protein in KO rats.Alcohol consumption was increased in Npy＋/- but not Npy-/- rats,while Npy-/- rats displayed significantly lower body weight when compared to Npy^（＋/＋） rats.In whole brain tissue,expression levels of Npy-related and other alcohol-associated genes,Npy1 r,Npy2r,Npy5 r,Agrp,Mc3 r,Mc4r,Crh and CrMr,were significantly greater in Npy-/- rats,whereas Pome and Crhr2 expressions were highest in Npy＋/- rats.These findings suggest that the NPY-system works in close coordination with the melanocortin（MC） and corticotropin-releasing hormone（CRH） systems to modulate alcohol intake and body weight.