Peptidergic hormones and neuropeptides, and aminergic neurotransmitters of the pancreatic islets of the Houbara bustard (Chlamydotis undulata)

Abstract

Immunoreactivity to insulin (Ins), somatostatin (Som), glucagon (Glu) and pancreatic polypeptide (PP) was found in 70 %, 22 %, 15 % and 11 % respectively of Houbara pancreatic endocrine islet cells. Whilst Ins occurred centrally and SOM was observed both in peripherally and centrally located islets, the other hormones were localised in peripheral islet cells ; Som was also observed in neuronal cell bodies and nerve fibres. In addition, the islet cells contained substance P (SP) (65 %) in the centre and vasoactive intestinal polypeptide (VIP) (2 %) at the periphery. Immunoreactivity to choline acetyltransferase (ChAT), VIP and galanin (Gal) occurred in the walls of blood vessels located mainly at the periphery of islets. Occasionally, VIP and Gal immunoreactive varicose nerve terminals and ChAT immunoreactive cell bodies were also observed in the centre of islets. SP neuronal cell bodies were not observed but prominent SP immunoreactive varicose terminals were discernible in capillary walls within the islets. Neuropeptide Y (NPY) immunoreactive neurons were detected in neuronal cell bodies located mainly peripherally. Neuronal nitric oxide synthase (nNOS) immunoreactivity occurred in neuronal cell bodies and nerve fibres mainly at the periphery and also in centrally located islet endocrine cells. Immunoreactivity to tyrosine hydroxylase (TH) was similar in distribution to that of ChAT. In comparison with other avian species, the islets of the dorsal pancreatic lobe of the bustard contain all the peptidergic hormones normally present in the islets of other avian species, but are not segregated into dark A and light B cells. Many of the insulin containing cells also contained SP. The islets also contained several neuropeptides which are probably involved in their regulation.

The Comparative Anatomy of Islets

“…Similar data were observed in the domestic duck, where A and mixed islets were more concentrated in the splenic lobe and decreased in number in the other lobes (Lucini et al 1996). Two exceptions to these species appear to be the Australian eagle and the Houbara bustard, which were reported not to have A and B islets but only islets of the mixed type, and no reciprocal relationship between PP and glucagon was observed (Edwin and Leigh 1993;Mensah-Brown et al 2000). More exceptions may well be observed as more species are studied, but one consistent finding is that birds tend to have large numbers of α-cells.…”

Pancreatic islet plasticity: Interspecies comparison of islet architecture and composition

“…β-cells are present in all four pancreatic lobes (i.e., dorsal, ventral, third and splenic) of the rose-ringed parakeet ( Psittacula krameri ) and α-cells only in the splenic and third lobes 87. In pancreatic islets of the Houbara bustard ( Chlamydotis undulata ), β-cells are located centrally and represent 70% of the endocrine cells, α-cells are found in the periphery at 15%, δ-cells are found in both central and peripheral regions at 22%, PP-cells are also in the periphery at 11%, and there is 20% overlap between α- and PP-cells 88. In some birds, such as the zebra finch ( Taeniopygia guttata ), β-cells are rare and δ-cells are more common 16…”

Differential distribution of calbindin D28k and parvalbumin among functionally distinctive sets of structures in the macaque brainstem

“…We previously conducted a detailed analysis (24) of a fragment spanning −3350 to +447 of the rPPT promoter, in order to delineate mechanisms that might regulate PPT‐A gene expression. This rPPT promoter and fragments derived from it are able to direct reporter gene expression in adult dorsal root ganglion (DRG) neurons grown in culture but have no detectable activity in nonneuronal cells in the same primary culture or in HeLa and PC12 cells (24–27). When this fragment, or a shorter fragment spanning −865 to +92, was used to drive expression of the β‐gal marker gene in a transgenic experiment, no direct reporter gene expression was observed (ref.…”

“…26, and Quinn JP: unpublished observations). The repression of promoter activity observed in the cells in vitro has been determined to be due to the presence of a repressor protein complex binding domain adjacent to the major transcriptional start site (25). The role of this repressor domain in the transgenic model was examined by replacing the PPT‐A minimal proximal promoter with that derived from the β‐globin promoter (23).…”

“…Recombinant AAV was prepared as previously described (25). Briefly, 1 × 10 7 293 cells were electroporated with 5 μg of pAAV/Ad and 5 μg of rAAV clone.…”