Elevated Body Weight Gain During the Juvenile Period Alters Neuropeptide Y-Gonadotropin-Releasing Hormone Circuitry in Prepubertal Heifers
Elevated Body Weight Gain During the Juvenile Period Alters Neuropeptide Y-Gonadotropin-Releasing Hormone Circuitry in Prepubertal Heifers
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DOI：
10.1095/biolreprod.114.124636
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发表时间：
2015-02-01
影响因子：
3.6
通讯作者：
Amstalden, Marcel
中科院分区：
文献类型：
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作者：
Alves, Bruna R. C.;Cardoso, Rodolfo C.;Amstalden, Marcel
幼年期体重的增加会导致生殖神经内分泌系统的提前成熟。我们调查了提前青春期开始的营养方案是否会导致下丘脑神经肽Y(NPY)回路的变化，这是允许促性腺激素释放激素(GnRH)分泌增加的原因。据推测，在幼年期，与体重较低的小母牛相比，体重加速增长的小母牛NPY mRNA和NPY向GnRH和Kispeptin神经元的投射减少。小母牛在大约4个月龄断奶，饲喂日粮以促进相对低(0.5公斤/天；低增重[LG])或高(1.0公斤/天；高增重[HG])的体重增重率，直到8.5mo龄。体重增加速度较快的小母牛表现出更高的瘦素循环浓度，并减少了弓状核中总体NPY的表达。与NPY纤维紧密结合的GnRH神经元的比例和投射到下丘脑内侧基底区的GnRH神经元的数量减少。然而，在HG和LG小母牛之间，没有发现NPY投射到弓状核内的Kispeptin神经元的差异。结果表明，在幼年期，GnRH神经元的NPY神经支配减少，特别是在下丘脑内侧基底水平，对增加的体重作出反应。这种功能可塑性可能有助于小母牛提早进入青春期。
Increased body weight (BW) gain during the juvenile period leads to early maturation of the reproductive neuroendocrine system. We investigated whether a nutritional regimen that advances the onset of puberty leads to alterations in the hypothalamic neuropeptide Y (NPY) circuitry that are permissive for enhanced gonadotropin-releasing hormone (GnRH) secretion. It was hypothesized that NPY mRNA and NPY projections to GnRH and kisspeptin neurons are reduced in heifers that gain BW at an accelerated rate, compared with a lower one, during the juvenile period. Heifers were weaned at approximately 4 mo of age and fed diets to promote relatively low (0.5 kg/day; low gain [LG]) or high (1.0 kg/day; high gain [HG]) rates of BW gain until 8.5 mo of age. Heifers that gained BW at a higher rate exhibited greater circulating concentrations of leptin and reduced overall NPY expression in the arcuate nucleus. The proportion of GnRH neurons in close apposition to NPY fibers and the magnitude of NPY projections to GnRH neurons located in the mediobasal hypothalamus were reduced in HG heifers. However, no differences in NPY projections to kisspeptin neurons in the arcuate nucleus were detected between HG and LG heifers. Results indicate that a reduction in NPY innervation of GnRH neurons, particularly at the level of the mediobasal hypothalamus, occurs in response to elevated BW gain during the juvenile period. This functional plasticity may facilitate early onset of puberty in heifers.