The influence of enteral obestatin administration to suckling rats on intestinal contractility.

This study investigated the effect of enteral administration of obestatin on the contractility of whole-thickness preparations of duodenum and middle jejunum, as well as on the morphology of the enteric nervous system (ENS). Suckling rats were assigned to 3 groups (n=12) treated with: C-saline solution; LO-obestatin (125nmol/kgb.wt); HO-obestatin (250nmol/kgb.wt). Saline solution or obestatin were administered twice daily, from the 14th to the 21st day of life. Sections were studied in an organ bath, for isometric recording in the presence of acetylocholine (ACh), atropine (ATR) and tetradotoxin (TTX). Thickness of intestinal muscularis layer, the number of interstitial cells of Cajal (ICC) were measured in the paraffin sections. The immunodetection of Muscarinic Acetylocholine Receptor 2 (M2 receptor) was performed in the intestinal segments. In both intestinal segments HO treatment decreased the amplitude of spontaneous contraction compared to that observed in the C group. In the middle jejunum, the LO treatment also decreased the amplitude. TTX and ATR had no effect on amplitude of spontaneous contraction in the jejunum of LO and HO-treated animals. Compared to the C group, duodenal sections from HO animals and middle jejunum sections from LO and HO groups displayed a lower amplitude in response to ACh and EFS evoked contraction. An increase in the thickness of the muscularis layer was observed in the duodenum of LO and HO groups whereas the number ICC did not change significantly after treatment with obestatin. Moreover, the enteral administration of obestatin did not effect significantly on the cytoplasmic expression of M2 receptor in the jejunum. Our study demonstrated that enteral administration of obestatin to suckling rats influences small intestine contractility in the segment specific manner.

Maternal high-fat diet during pregnancy and lactation had gender difference effect on adiponectin in rat offspring.

This study investigated the effect of a high-fat (HF) diet on plasma adiponectin and steroid hormones levels, and the protein expression of adiponectin and its receptors, in the gonads and gonadal (periovarian and epididymal) white adipose tissue (WAT) of dams and their offspring. Female Wistar rats were fed a HF diet (30% fat) or a standard breeding (BD) diet (5% fat) during pregnancy and lactation. At 21 days of lactation, mothers and both sexes of prepubertal offspring were killed by decapitation. Plasma adiponectin, testosterone (T) and oestradiol (E2) levels were analyzed by ELISA. The protein expression of adiponectin and its receptors 1 (AdipoR1) and 2 (AdipoR2) was assayed by Western blot and immunohistochemistry. Plasma adiponectin levels in HF dams were lower compared to BD dams, and correlated with protein expression of adiponectin and its receptors, but not with steroid hormone levels. Female HF offspring had lower plasma adiponectin levels, reduced intensity of adiponectin and AdipoR1 in the ovary, and decreased E2 in parallel with increased T. In contrast, male HF offspring had higher plasma adiponectin levels, increased intensity of adiponectin and AdipoR1 in the testis, and decreased T in parallel with increased E2. In conclusion, feeding a HF diet to dams during pregnancy and lactation disturbs plasma adiponectin levels and protein expression, both in female and male offspring; it lowers adiponectin secretion and protein expression in the female whereas in male it is increased. As a consequence, there is disruption of steroid secretion in offspring, towards T in females, and E2 in males.

Age-dependent effect of obestatin on intestinal contractility in Wistar rats.

Obestatin is a 23-amino acid peptide encoded by the ghrelin gene. We have investigated the effect of obestatin on intestinal contractility in rats ranging from the suckling period till adolescence. Duodenal and middle jejunum whole-thickness preparations from neonatal and adult rats were studied in an organ bath, for isometric recording under treatment with obestatin (1µmolL(-1)) in the presence of acetylocholine (ACh), atropine and tetradotoxin (TTX). Both the EFS and ACh-stimulated contractile response, as well as spontaneous contractile activity is age-dependent and specific for the segment of jejunum. Except for the middle jejunum of 7day old rats, treatment with obestatin caused a significant TTX-sensitive increase in the amplitude of EFS-stimulated off-contraction of both intestinal segments studied. Following injection of obestatin, the amplitude of spontaneous contraction in the duodenum increased in 7day old rats. In the middle jejunum, treatment with obestatin significantly increased both the amplitude and frequency of spontaneous contraction in rats till the 28th day of life, whereas in adult rats the observed effect of obestatin was the opposite (P<0.001 and P<0.0001, respectively). The effects of treatment with obestatin on stimulation with increasing doses of ACh were only observed in the preparations from suckling rats. ACh-stimulated contractility in the duodenum was decreased while in the middle jejunum the observed effect was opposite. These results indicate the importance of peripheral obestatin in the cholinergic control of intestinal contractility in both neonatal and adult rats.

Enteral leptin administration affects intestinal autophagy in suckling piglets.

Leptin has been shown to play an integral role in the endocrine regulation of metabolism. Moreover, a substantial amount of this peptide has been found in colostrum and milk. The aim of the study was to investigate the effects of exogenous leptin, administered intragastrically, on the process of autophagy and the changes in cell hyperplasia and hypertrophy in the small intestine mucosa. Three groups (n = 6) of neonatal piglets were used in the study. The pigs were fed either by their sows (sow-reared piglets) or with only milk formula, or with milk formula together with leptin administered via a stomach tube (10 µg/kg BW) every 8 h for 6 d. We have shown that pure milk formula feeding significantly elevates (P < 0.05) autophagy compared with that observed in sow-reared piglets. Compared with the control group, feeding milk formula supplemented with leptin resulted in a significant decrease (P < 0.05) in immunodetection of microtubule-associated protein 1 light chain 3, as well as significantly accelerated epithelial cell renewal (P < 0.05). We demonstrated that autophagy is involved in the remodeling of the small intestine mucosa and that leptin, when administered enterally, may be an important factor for its regulation.

Stimulating effect of pancreatic-like enzymes on the development of the gastrointestinal tract in piglets.

Use of nutritional components from the milk and eventually from the solid feed relates to the growth and development of gastrointestinal tract (GIT). We studied the effect of pancreatic-like enzymes [porcine pancreatic enzymes (Creon) or microbial-derived amylase, protease, and lipase] on GIT morphology and lipid absorption in suckling piglets. Both enzyme preparations, in low or high dose, were fed via a stomach tube twice a day for 7 d starting at 8 d of age and controls received vehicle, n = 6. The day after treatments ended, lipid absorption was tested after which pigs were euthanized and GIT was examined. Enzyme cocktails, irrespective of their origin, increased (P < 0.001) triglyceride level in blood. Enzyme preparation affected (P < 0.001) small intestinal mucosal thickness, villi length, and crypt depth and (P < 0.01) mitotic division of enterocytes. In addition, the external administration of pancreatic enzymes stimulated pancreatic growth as observed by increased (P < 0.05) mitotic division of pancreatic cells. The study revealed that pancreatic or pancreatic-like enzymes of microbial origin administrated in the early postperinatal period enhance GIT development and may be used to better prepare the GIT of piglets for milk use and weaning.

Effect of feeding colostrum versus exogenous immunoglobulin G on gastrointestinal structure and enteric nervous system in newborn pigs.

Colostrum is an indispensable source of antibodies (IgG) protecting the newborn pig against infection. We studied the effect of feeding colostrum and purified IgG on early structure and development of the gastrointestinal tract (GIT). Newborn littermate pigs were fed either colostrum, an elemental diet (ED), or an ED supplemented with purified serum IgG (ED + IgG) for 24 h or then only ED up to 72 h. Afterwards, pigs were slaughtered. Colostrum-fed pigs or ED supplemented with IgG (ED + IgG) increased thickness (P < 0.001) of stomach mucosa and muscularis (P < 0.05) compared to the ED group not receiving IgG. Feeding an ED supplemented with IgG improved morphology of the GIT towards that of colostrum-fed piglets and indicates a beneficial effect of IgG on GIT development in neonatal pigs. Immunohistochemical studies indicate that ED feeding may influence the expression of nitric oxide synthase in jejunal myenteric (but not submucous) neurons of newborn pigs.

Into the unknown--the death pathways in the neonatal gut epithelium.

Apoptosis is a fundamental process in the development of the fast growing intestinal mucosa. Apoptotic cells are present along the whole length of the villi and in the crypts. The mechanisms involved in the induction of apoptosis in the gut mucosa are still unknown. Cytokines are believed to play a role in auto- and paracrine models because the cells are dying in so-called "packets" containing neighboring cells. In the rapidly developing gut of neonates, the apoptosis rate is transiently reduced in the first days of life, enhancing the growth of mucosa. Afterwards, apoptosis plays a role in the exchange of the enterocyte population, facilitating maturation of the mucosa. The presence of autophagic cells has been confirmed for the first time in the developing gut. Deprivation of growth factors during feeding artificial milk formula led to an increased apoptosis rate. Supplementation with leptin reduced cell apoptosis and increased the mitosis-to-apoptosis ratio. Autophagy was also diminished. The key to healthy gut mucosa growth in early life, especially in fast-growing animals, is colostrum, which supplies nutritional and defensive components together with supplementary growth factors, cytokines and hormones essential for growth and maturation of gut mucosa.