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Nutritional control of puberty in the bovine female: prenatal and early postnatal regulation of the neuroendocrine system
کنترل تغذیه ای بلوغ در گاو های ماده : تنظیم پیش از تولد و زودرس پس از زایمان سیستم عصبی و غدد درونریز-2020 Puberty is a complex biological event that requires maturation of the reproductive
neuroendocrine axis and subsequent initiation of high-frequency, episodic release of GnRH
and LH. Nutrition is a critical factor affecting the neuroendocrine control of puberty.
Although nutrient restriction during juvenile development delays puberty, elevated rates
of body weight gain during this period facilitate pubertal maturation by programming
hypothalamic centers that underlie the pubertal process. Recent findings suggest that
maternal nutrition during gestation can also modulate the development of the fetal
neuroendocrine axis, thus influencing puberty and subsequent reproductive function.
Among the several metabolic signals, leptin plays a critical role in conveying metabolic
information to the brain and, consequently, controlling puberty. The effects of leptin on
GnRH secretion are mediated via an upstream neuronal network because GnRH neurons
do not express the leptin receptor. Two neuronal populations located in the arcuate nucleus
that express the orexigenic peptide neuropeptide Y (NPY), and the anorexigenic
peptide alpha melanocyte-stimulating hormone (aMSH), are key components of the
neurocircuitry that conveys inhibitory (NPY) and excitatory (aMSH) inputs to GnRH neurons.
In addition, neurons in the arcuate nucleus that coexpress kisspeptin, neurokinin B,
and dynorphin (termed KNDy neurons) are also involved in the metabolic control of puberty.
Our studies in the bovine female demonstrate that increased planes of nutrition
during juvenile development lead to organizational and functional changes in hypothalamic
pathways comprising NPY, proopiomelanocortin (POMC, the precursor of aMSH),
and kisspeptin neurons. Changes include alterations in the abundance of NPY, POMC, and
Kiss1 mRNA and in plasticity of the neuronal projections to GnRH neurons. Our studies also
indicate that epigenetic mechanisms, such as modifications in the DNA methylation
pattern, are involved in this process. Finally, our most recent data demonstrate that
maternal nutrition during gestation can also induce morphological and functional changes
in the hypothalamic NPY system in the heifer offspring that are likely to persist long after
birth. These organizational changes occurring during fetal development have the potential
to not only impact puberty but also influence reproductive performance throughout
adulthood in the bovine female. Keywords: Heifers | Hypothalamus | Leptin | Nutrition | Puberty |
مقاله انگلیسی |
2 |
Hypothalamic Interactions with Large-Scale Neural Circuits Underlying Reinforcement Learning and Motivated Behavior
تعاملات هیپوتالاموس با مدارهای عصبی در مقیاس بزرگ زمینه یادگیری تقویتی و رفتار انگیزه ای-2020 Biological agents adapt behavior to support the survival needs of the individual
and the species. In this review we outline the anatomical, physiological, and
computational processes that support reinforcement learning (RL). We describe
two circuits in the primate brain that are linked to specific aspects of learning and
goal-directed behavior. The ventral circuit, that includes the amygdala, ventral
medial prefrontal cortex, and ventral striatum, has substantial connectivity with
the hypothalamus. The dorsal circuit, that includes inferior parietal cortex, dorsal
lateral prefrontal cortex, and the dorsal striatum, has minimal connectivity with
the hypothalamus. The hypothalamic connectivity suggests distinct roles for
these circuits. We propose that the ventral circuit defines behavioral goals, and
the dorsal circuit orchestrates behavior to achieve those goals. |
مقاله انگلیسی |