Effect of cysteamine on gastric nerve fibers containing gastrin-releasing peptide in the rat

The innervation of the human antro-pyloric region: Organization and composition

Although the composition of the gastric innervation has been determined in animal models, relatively little known about the innervation of the human antro-pyloric region. We used immunocytochemical techniques to establish the localization and co-expression of neuropeptides and nitric oxide in the human antrum and upper duodenum. Our results demonstrate the existence of a clearly defined submucosal plexus in the antral region that is absent in rats and guinea pigs. The abundant innervation of the lamina propria contains 3 major nerve populations: VIP- and NOS-, SP- and CGRP-, and GRP-immunoreactive. For the first time, NOS-containing nerve fibers were observed throughout the length of the antral glands. Within the antrum somatostatin was confined to endocrine cells, however, at the pyloric sphincter both enteric plexi contained immunoreactive neurons and nerve fibres. Within the pyloric sphincter CGRP- and SP-immunoreactive fibres were significantly increased, correlating with the presence of large ganglia in the submucosal plexus. In conclusion, the organization and composition of the innervation of human antro-pylorus differed substantially from that reported in other mammals. The presence of an abundant mucosal innervation paralled by a well-defined submucosal plexus indicates that the functional regulation of the gastric–pyloric region will be distinct from that of smaller animal models.Key words: gastric innervation, pyloric sphincter, neuropeptides, nitric oxide, somatostatin.

Ultrastructural and histochemical characterization of special muscle cells in the monkey small intestine

The ultrastructure, three-dimensional arrangement, and histochemical features of special muscle cells in the monkey small intestine were investigated. The cells formed a special layer separated from the main part by a connective tissue space along the submucosal surface of the circular muscle coat. Scanning electron microscopy using alkali maceration demonstrated this inner sublayer to be a continuous thin sheet consisting of irregularly-shaped muscle cells equipped with many cytoplasmic projections and caveolae. Other ultrastructural features included direct contact with interstitial cells, due to their close association with nerve fibers of the deep muscular plexus. Histochemical examination revealed significant alkaline phosphatase activity and immunoreactivity for vascular smooth muscle alpha actin in these muscle cells, whereas the ordinary circular muscle cells were immunopositive for enteric smooth muscle gamma actin. These findings suggest that the special muscle cells play an important role in regulating the radial stretch of the monkey small intestinal wall.

Characteristics of monocarboxylates as energy substrates other than glucose in rat brain slices and the effect of selective glial poisoning - a 31P NMR study

In rat brain slices we examined the differences in the levels of high-energy phosphates in the presence of various energy substrates by using 31P NMR with a time resolution of 4 min at 25 degrees C. In parallel experiments we recorded population excitatory postsynaptic potentials (EPSPs) from granule cells in rat hippocampal slices. During high K(+) stimulation (8 min) phosphocreatine (PCr) decreased to a low level and recovered to the control level in standard artificial cerebrospinal fluid (ACSF) in about 10 min. Population EPSPs disappeared following high-K(+) stimulation and recovered in standard ACSF. In iodoacetic acid (IAA)-pretreated slices, whereas glucose was unable to support energy metabolism, the PCr level, which decreased following high-K(+) stimulation, recovered in ACSF containing lactate or pyruvate. The half-time of recovery of PCr levels in ACSF containing lactate was longer than that containing glucose. Population EPSPs in standard ACSF were maintained for more than 1 h, but those in ACSF containing lactate decreased gradually by about half in 40 min. In IAA-pretreated slices, when further treated with fluorocitrate (100 microM) for 2 h, the recovery of the PCr level in ACSF containing lactate after high-K(+) stimulation was completely abolished, whereas the recovery of the PCr level in ACSF containing pyruvate was unaffected. These results indicate that neurons can utilize pyruvate as well as glucose, but not lactate, as exogenous energy substrates, and that lactate may be metabolized to pyruvate in glial cells and transported to neurons to be utilized as an energy substrate.