Anatomical relationship between enkephalin-containing neurones and caecum-projecting neurones in the chicken intestinal nerve

Perspectives on Endogenous Opioids in Birds

The present review summarizes the state of knowledge of endogenous opioids in birds. Endogenous opioid peptides acts in a neuromodulatory, hormonal and paracrine manner to mediate analgesic and other physiological functions. These peptides act through specific G-protein coupled receptors. Opioid receptors consist of a family of four closely-related proteins. The three types of opioid receptors are the mu (MOR or μ), delta (DOR or δ), and kappa (KOR or κ) opioid receptor proteins. The role of the fourth member of the opioid receptor family, the nociceptin or orphanin FQ receptor (ORL), is not clear. The ligands for opioid receptors are: β –endorphin (MOR), Met- enkephalin, Leu-enkephalin (DOR) and dynorphin (KOR), together with probably endomorphins 1 and 2. In spite of long history of research on endogenous opioid peptides, there are no studies of endogenous opioids per se in wild birds and few in poultry species. β-endorphin is present in all birds investigated and there is close agreement between the structures of β-endorphin in different birds. Plasma concentrations of β-endorphin are increased by ether stress in geese. There is evidence that β-endorphin plays a role in the control of luteinizing hormone release in chickens. Met-enkephalin is present in tissues such as the retina, hypothalamus, pituitary gland, and adrenals together with circulation of birds. Stresses such as crowding and withholding water increase circulating concentrations of Met-enkephalin in chickens. The structures of chicken dynorphin A and B have been deduced from cDNA. What is missing are comprehensive studies of plasma concentrations and expression of the full array of endogenous opioids in multiple avian species under different situations. Also, what is not known is the extent to which circulating or locally released or intra-cellular Met-enkephalin influence physiological process in birds. Thus, there is considerable scope for investigation of the physiology of endogenous opioids in birds.

Molecular analysis of microbial community structure in the chicken ileum following organic acid supplementation

To compensate for possible decreases in animal production due to restrictions on the use of antibiotics as growth promoters, several non-antibiotic alternatives have been investigated. Organic acid supplementation (OAS) of feed or water has shown some promising results for affecting intestinal microbiota and reducing pathogenic bacteria in the gastrointestinal (GI) tract. However, few studies have explored the effects of OAS on microbial communities using objective molecular-based techniques. The aim of the present study was to characterize via 16S rRNA gene-based approaches responses of the intestinal microbiota after OAS in chicks. Newborn chicks were randomly divided in four treatments: (a) control (no antibiotic, no OAS); (b) antibiotic administration (bacitracin MD); (c) organic acid blend dl-2-hydroxy-4(methylthio) butanoic acid [HMTBA]; lactic, and phosphoric acid (HLP); and (d) organic acid blend HMTBA, formic, and propionic acid (HFP). Ileal contents and mucosal scrapings from 7 chicks/treatment/day were taken at 15, 22, and 29 days of age, and genomic DNA was isolated for the molecular analysis of the intestinal microbiota. The data demonstrate that HFP blend treatment for 29 consecutive days affected ileal microbial populations as indicated by community fingerprinting analysis (16S rRNA PCR-DGGE). In parallel, total bacterial and lactobacilli populations were increased by the HFP blend treatment as demonstrated by targeted qPCR analysis of 16S rRNA. In summary, the present data demonstrate that OAS, HFP blend treatment in particular, shifts intestinal microbiota, generates more homogenous and distinct populations, and increases Lactobacillus spp. colonization of the chick ileum.

Endogenous opiates and behavior: 2003

This paper is the 26th consecutive installment of the annual review of research concerning the endogenous opioid system, now spanning over a quarter-century of research. It summarizes papers published during 2003 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurologic disorders (Section 11); electrical-related activity and neurophysiology (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration and thermoregulation (Section 16); and immunological responses (Section 17).