Intestinal epithelial cells express leptin receptors that modulate the oligopeptide transporter Pept-1

Mammary leptin synthesis, milk leptin and their putative physiological roles

“…This hypothesis is supported by observations made in adult humans and rodents, where leptin, via the leptin receptor localized in gastric [12] or intestinal [15,58,64] mucosa, could be involved in the control of meal size in co-operation with cholecystokinine, in the cytoprotection of gastric mucosa, in gut inflammatory processes and in the secretion of gastric hormones such as gastrin and somatostatin [54], in the proliferation of intestinal cells [3,34] and in the transport of nutrients [15,64,70].…”

“…Besides synthesizing leptin, secretory epithelial cells may transfer leptin from the blood, and these two mechanisms may account for the enterocytes which are permeable to macromolecules, as reported for other colostral proteins [6] and/or the transport by short leptin receptor isoforms, whose expression has been shown in human and rodent small intestines [15,58,64]. Once absorbed, a role for leptin in neonate immunity could be hypothesized in view of the results obtained in transgenic mice models such as ob/ob and db/db treated or not by leptin as well as in normal rodents and humans, that showed that leptin modulates cytokine production and the thymus size, the activation of monocytes/macrophages, the proliferation/apoptosis of T lymphocytes and the T helper (Th)1/(Th)2 balance [28,57,62].…”

Apolipoprotein A-IV: a protein intimately involved in metabolism

“…Gastric leptin can be secreted into the blood stream as well as into the gastric lumen, where it is resistant to the proteolysis in the stomach ( 115 ). The secretion of gastric leptin is stimulated by nutrients, vagal stimulation, and several hormones, including cholecystokinin (CCK) and insulin ( 111,116,117 ).…”

Gastric leptin

“…The functional long isoform of leptin receptor (ob-RL) (Tartaglia et al, 1995) has been identified in the duodenum and the jejunum (Buyse et al, 2000) Furthermore, evidence has been provided that leptin can regulate intestinal triglycerides transport by inhibiting apolipoprotein AIV transcription via activation of a jejunal leptin receptor (Morton et al, 1998). In addition, we have recently reported that jejunal perfusion of leptin in the anesthetized rat increased oligopeptide transport by the apical transporter Pept-1 (Buyse et al, 2000).…”

“…Rather, they could reflect local endocrine or paracrine effects such as modulation of hepatic glucose metabolism or activation of nerves endings in the gastric and intestinal mucosae. On the other hand, leptin secreted in the gastric juice shows a remarkable resistance to proteolytic degradation and, thus, has the potential to act on luminal targets (Buyse et al, 2000).…”