Effects of maternal deprivation on the somatotrophic axis and neuropeptide Y in the hypothalamus and pituitary in female lambs. The histomorphometric study.

Abstract

Abstract:The effects of maternal deprivation on the somatotrophic axis and neuropeptide Y (NPY) neuronal system in the hypothalamus of female lambs were evaluated. Twelve-week-old lambs were divided into two groups: the control (lambs stayed with mothers) and maternally deprived (MD; lambs separated for 3 days from mothers). The expression of immunoreactive (ir) somatostatin in the neurons of the periventricular nucleus (PEV) and in nerve terminals of the median eminence (ME), growth hormone (GH) in the adenohypophyseal cells and NPY in the neurons of the PEV and arcuate (ARC) nuclei of the hypothalamus using immunohistochemistry followed by the image analysis were estimated. Concentrations of GH in the blood plasma were determined by radioimmunoassay. The expression of ir somatostatin in the PEV and ME, ir NPY in the ARC and PEV, ir GH in adenohypophyseal cells, and blood plasma GH concentrations were greater (p<0.05) in MD than in the control lambs. In conclusion, MD affects the somatotrophic axis by enhancement of GH secretion via restraining of somatostatin output. The simultaneous increase of expression of hypothalamic ir NPY suggests NPY involvement in the regulation of psychoemotional stress through the somatotrophic axis in the female lambs.

Activation of Brain Somatostatin Signaling Suppresses CRF Receptor-Mediated Stress Response

“…In particular, immobilization (Negro-Vilar and Saavedra, 1980; Arancibia et al, 2000), handling (Arancibia et al, 1984), maternal separation (Polkowska and Wankowska, 2010), hypoxia (Chen and Du, 2002), pain (Arancibia et al, 1984), and injection of endotoxin (Priego et al, 2005) increase hypothalamic somatostatin mRNA levels and peptide release. Somatostatin release also occurred in the dorsal dentate gyrus in rats subjected to immobilization (Arancibia et al, 2001).…”

The role of brain somatostatin receptor 2 in the regulation of feeding and drinking behavior

“…The enhanced somatostatin release under conditions of acute stress is further supported by the finding of reduced peptide content in the supraoptic nucleus and the PVN, the locus coeruleus and nucleus of the solitary tract in the rat brainstem (Arancibia et al, 2000; Negro-Vilar and Saavedra, 1980). Likewise, in lambs the stress of maternal separation enhanced somatostatin concentration in nerve terminals of the median eminence (Polkowska and Wankowska, 2010). Other studies also showed that rats exposed to an elevated plus maze displayed activation of somatostatin neurons in the basolateral amygdala (Butler et al, 2012).…”

Modulation of the adaptive response to stress by brain activation of selective somatostatin receptor subtypes

“…Several types of stressors namely handling, exposure to nociceptive stimuli, immobilization, or low doses of endotoxin increased hypothalamic somatostatin mRNA levels or peptide release from the median eminence in rats [2, 3, 73]. Likewise, in young lambs somatostatin is elevated in nerve terminals of the median eminence after three days of maternal separation [71]. A decrease in peptide content in the hypothalamus (supraoptic nucleus, PVN) and extrahypothalamic areas including the locus coeruleus and nucleus of the solitary tract after acute stress in rats is also indicative of a somatostatin release from those brain nuclei [3, 68].…”