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At least 613 records · Page 34Linked to original sources
PubMed2005

Cholecystokinin1 receptors mediate the increase in Fos-like immunoreactivity in the rat myenteric plexus following intestinal oleate infusion.

Intestinal infusion of nutrients, such as glucose and oleic acid, increase Fos-like immunoreactivity (Fos-LI) in both the enteric nervous system and neurons of the dorsal vagal complex (DVC) of the hindbrain. To test the hypothesis that increased Fos-LI in enteric neurons and the DVC, following intestinal nutrient infusions is mediated by cholecystokinin(1) receptors (CCK(1)), we counted enteric and DVC neurons that expressed Fos-LI following intestinal infusion of oleate or glucose, with and without pretreatment with the CCK(1) receptor antagonist, lorglumide. Both oleate and glucose infusions increased Fos-LI in the DVC. Oleate also increased Fos-LI in the myenteric and submucosal plexuses of the duodenum and the jejunum, but not the ileum, while glucose only increased Fos-LI in the submucosal plexus of the ileum. The CCK(1) receptor antagonist, lorglumide, abolished Fos-LI in the DVC following infusions of either oleate or glucose. In addition, lorglumide attenuated oleate-induced Fos-LI in the myenteric and submucosal plexuses of the duodenum and jejunum. However, lorglumide failed to attenuate glucose-induced Fos-LI in the submucosal plexus of the ileum. These data confirm previous reports indicating that CCK(1) receptors mediate increased DVC Fos-LI following intestinal infusion of oleate or glucose. CCK(1) receptors also contribute to increased Fos-LI in enteric neurons following intestinal oleate infusion. However, failure of lorglumide to attenuate the increase of Fos-LI in the ileal submucosal plexus following intestinal glucose suggests that some intestinal nutrients trigger Fos-LI induction via CCK(1) receptor-independent pathways.

Animals↗
PubMed1999

Correlation of morphology, electrophysiology and chemistry of neurons in the myenteric plexus of the guinea-pig distal colon.

Intracellular recordings were made from myenteric neurons of the guinea-pig distal colon to determine their electrical behaviour in response to intracellular current injection and stimulation of synaptic inputs. The recording microelectrode contained the intracellular marker biocytin, which was injected into impaled neurons so that electrophysiology, shape and immunohistochemistry could be correlated. Myenteric neurons in the distal colon were divided into four morphological groups based on their shapes and projections. One group (29 of the 78 that were characterized electrophysiologically, morphologically and immunohistochemically) was the multiaxonal Dogiel type II neurons, the majority (25/29) of which were calbindin immunoreactive. Each of these neurons had an inflection on the falling phase of the action potential that, in 24/29 neurons, was followed by a late afterhyperpolarizing potential (AHP). Slow excitatory postsynaptic potentials were recorded in 20 of 29 Dogiel type II neurons in response to high frequency internodal strand stimulation and two neurons responded with slow inhibitory postsynaptic potentials. Low amplitude fast excitatory postsynaptic potentials occurred in 3 of 29 Dogiel type II neurons. Neurons of the other three groups were all uniaxonal: neurons with Dogiel type I morphology, filamentous ascending interneurons and small filamentous neurons with local projections to the longitudinal or circular muscle or to the tertiary plexus. Dogiel type I neurons were often immunoreactive for nitric oxide synthase or calretinin, as were some small filamentous neurons, while all filamentous ascending interneurons tested were calretinin immunoreactive. All uniaxonal neurons exhibited prominent fast excitatory postsynaptic potentials and did not have a late AHP following a single action potential, that is, all uniaxonal neurons displayed S type electrophysiological characteristics. However, in 6/19 Dogiel type I neurons and 2/8 filamentous ascending interneurons, a prolonged hyperpolarizing potential ensued when more than one action potential was evoked. Slow depolarizing postsynaptic potentials were observed in 20/29 Dogiel type I neurons, 6/8 filamentous ascending interneurons and 8/12 small filamentous neurons. Six of 29 Dogiel type I neurons displayed slow inhibitory postsynaptic potentials, as did 2/8 filamentous ascending interneurons and 4/12 small filamentous neurons. These results indicate that myenteric neurons in the distal colon of the guinea-pig are electrophysiologically similar to myenteric neurons in the ileum, duodenum and proximal colon. Also, the correlation of AH electrophysiological characteristics with Dogiel type II morphology and S electrophysiological characteristics with uniaxonal morphology is preserved in this region. However, filamentous ascending interneurons have not been encountered in other regions of the gastrointestinal tract and there are differences between the synaptic properties of neurons in this region compared to other regions studied, including the presence of slow depolarizing postsynaptic potentials that appear to involve conductance increases and frequent slow inhibitory postsynaptic potentials.

Afferent Pathways↗