Hypothalamic arcuate neuropeptide Y-neurons decrease periventricular somatostatin-neuronal activity before puberty in the female lamb: Morphological arguments

The effect of intracerebroventricular infusions of ghrelin or short fasting on the gene expression and immunoreactivity of neuropeptide Y in the hypothalamic neurons in prepubertal female lambs: A morphofunctional study

“…Immunohistochemical studies have demonstrated synaptic connections between NPY containing axons and somatostatin perikarya in the PEV nucleus of rats (Hisano et al, 1990) and sheep (Iqbal et al, 2005). The direct morphological connections between NPY fibres and somatostatin perikarya are increased, during the period of the enhanced GH release due to decrease of the somatostatin output (Tillet et al, 2010). It was concluded that PEV nucleus is the site of interactions between the two neuropeptides in the regulation of GH secretion.…”

“…The hypothesis that in sheep NPY would suppress somatostatin activity is supported by some evidences (Iqbal et al, 2005;Tillet et al, 2010). However the role of ghrelin in the central regulation of endocrine functions in sheep and especially the functional linkage between the mechanism of ghrelin action on GH secretion is still being investigated.…”

Localization of kisspeptin neurons in the hypothalamus of peripubertal female lambs; possible connection with gonadotrophin releasing hormone and neuropeptide Y neurons

“…In 32-week-old female lambs, we demonstrated that the activity of NPY neurons of the ARC nucleus decreased simultaneously with the number of NPY afferent on PEV somatostatin neurons (Tillet et al, 2010). These results indicate that NPY neurons of the ARC nucleus are able to inhibit growth by suppressing the negative feedback on the somatostatin neurons in the PEV nucleus.…”

“…Sections from the caudal aspect of the arcuate nucleus (ARC) were simultaneously incubated with a mixture of anti-kp raised in rabbit and diluted 1: 2,000 and with anti-NPY raised in guinea pig and diluted 1: 5,000 according to a previously described procedure (Chaillou et al, 1998;Tillet et al, 2010). After three washes, the primary antibodies were detected using immunofluorescence by incubating the sections simultaneously in a mixture of fluorescent donkey immunoglobulin antiguinea pig IgG (CyTM)I diluted 1:1,000 and antirabbit IgG (fluoroprobe 488) diluted 1:500 (Jackson Immunoresearch Laboratories Inc.).…”

Does obestatin modulate the hypothalamic appetite‐regulating network in peripubertal sheep?

“…Neuropeptide Y is largely distributed in the central nervous system (CNS) but its role in appetite regulation is attributed to the subpopulation of neurons located in the ARC nucleus (Lopaschuk et al., ) and this hormone has been recognized as a powerful hormone with orexigenic properties (stimulation of appetite and food intake). Moreover, NPY neurons in the ARC nucleus are primary targets for many orexigenic and anorexigenic peripheral hormones (Gładysz, Krejci, Simůnek, & Polkowska, ; Tillet et al., ). Our previous studies confirmed that peripheral peptides, such as leptin and ghrelin, are involved in the modulation of hypothalamic appetite‐regulating network activity in sheep, and this modulation occurs via NPY neurons in the ARC nucleus (Polkowska, Gajewska, Wańkowska, Misztal, & Wójcik‐Gładysz, ; Tillet et al., ; Wójcik‐Gładysz, Wańkowska, Misztal, Romanowicz, & Polkowska, ; Wójcik‐Gładysz et al., ).…”