Pregnancy-induced mechanisms regulating central and peripheral leptin sensitivity: lessons from sheep.

This review describes various aspects of the leptin resistance phenomenon and related physiological mechanisms that occur in pregnant sheep. Its main aim is to analyze the mechanisms that determine the occurrence of pregnancy-induced leptin resistance and to investigate the accompanying processes that affect the physiology of pregnancy and lactation in livestock. The main purpose of this analysis was to comprehensively understand the phenomenon of leptin resistance, including the causes of its emergence and its effects on nonrodent organisms.

Seasonal and nutritional changes in the short form of the leptin receptor expression and VEGF system in the choroid plexus, arcuate nucleus, and anterior pituitary in MTS-leptin and resistin-treated sheep.

The short form of the leptin receptor (LeptRa) plays a key role in the transport of leptin to the central nervous system (CNS). Here, MTS-leptin and recombinant ovine (ro) leptin-mediated expression of LeptRa and VEGFA and VEGFR2 concentration in selected hypothalamic nuclei, choroid plexus (ChP), and anterior pituitary (AP) were analyzed considering the photoperiod and acute-fasting (experiment 1), and nutritional status (experiment 2) of ewes. In experiment 1, 60 sheep were fed normally or fasted for 72 h and received one injection of saline, MTS-leptin, or roleptin 1 h prior to euthanasia.

Effects of Leptin, Growth Hormone and Photoperiod on Pituitary SOCS-3 Expression in Sheep.

This study examined how leptin affects growth hormone (GH) release and investigated the effects of leptin, GH, and day length on the suppressor of cytokine signaling-3 (SOCS-3) mRNA levels in the adenohypophyses of sheep. The study consisted of two experiments. The first experiment was conducted during long (LD) and short (SD) days.

Seasonal and Nutritional Fluctuations in the mRNA Levels of the Short Form of the Leptin Receptor () in the Hypothalamus and Anterior Pituitary in Resistin-Treated Sheep.

The short form of the leptin receptor () plays a key role in the transport of leptin to the central nervous system (CNS). Here, the resistin (RSTN)-mediated expression of in the preoptic area (POA), ventromedial and dorsomedial nuclei (VMH/DMH),arcuate nucleus (ARC) and the anterior pituitary gland (AP)was analyzed considering the photoperiodic (experiment 1) and nutritional status (experiment 2) of ewes. In experiment 1, 30 sheep were fed normally and received one injection of saline or two doses of RSTN one hour prior to euthanasia.