Electrophysiology and enkephalin immunoreactivity of identified myenteric plexus neurones of guinea‐pig small intestine.

Abstract

SUMMARY1. Intracellular injection of the fluorescent dye, Lucifer Yellow CH, revealed the shapes of neurones in the myenteric plexus of the guinea-pig ileum, and these shapes were correlated with the electrophysiological properties and enkephalin immunoreactivity of the neurones.2. A total of eighty-three neurones were filled using electrodes containing a 5 % solution of the dye. Forty-six cells had many short processes and a single long process (Dogiel type 1) and twenty-four cells had essentially smooth somas and one to eight long processes (Dogiel type II). Thirteen cells could not be put into either group. Enkephalin-like immunoreactivity was detected in twenty-two of the forty-six Dogiel type I cells. Eighteen of these had club-like short processes. No other cells of the eighty-three showed enkephalin-like immunoreactivity.3. Electrodes filled with a 0 5 % solution of Lucifer Yellow in 0 5 M-KCl were used to record from and simultaneously to inject dye into 240 neurones. Eighty-six nerve cells had a slow after-hyperpolarization following the action potential (AH cells) and forty-six nerve cells had no after-hyperpolarization but exhibited a fast excitatory synaptic potential (S cells). The other cells could not be unequivocally identified by their observed electrophysiological characteristics. Almost all S cells (forty-two of forty-six) were Dogiel type I, while eighty-two of the eighty-six AH cells were Dogiel type II.4. Fifty S cells (eight located geometrically, forty-two by dye injection) and ninety-one AH cells (twenty-six located geometrically, sixty-five by dye i.,, action)were examined for enkephalin immunoreactivity. Fifteen of the S cells were reactive, whereas all of the AH cells were unreactive. It appears that prolonged impalements reduce immunoreactivity so that the proportion of reactive neurones in this series is an underestimate of the true proportion of S cells with enkephalin-like immunoreactivity.5. The results suggest that a substantial proportion of the S cells in myenteric

Ultrastructural analysis of substance P-immunoreactive nerve fibers in myenteric ganglia of guinea pig small intestine

“…Between 10 and 35% of myenteric neurons belong to this group (Furness and Costa, 1987). These neurons have large, smooth cell bodies (Dogiel Type II morphology), are usually located centrally within the ganglia, and often give rise to several long processes (Bomstein et al, 1984a;Erde et al, 1985;Iyer et al, 1988). About 85% of AH neurons are immunoreactive for calcium binding protein (calbindin D 28K) and do not provide terminals to the muscle (Furness et al, 1988a;Iyer et al, 1988).…”

Long aboral projections of Dogiel type II, AH neurons within the myenteric plexus of the guinea pig small intestine

“…A variety of characteristics can be used to identify AH cells; chief among them is the long afterhyperpolarization that follows their action potentials (see Wood, 1994, for reviews). Many AH cells have been demonstrated to have Dogiel type II morphological features (Bornstein et al, 1984;Erde et al, 1985;Katayama et al, 1986;Iyer et al, 1988;Hendriks et al, 1990;Bornstein et al, 1991) with large round or oval cell bodies and several long, tapering processes that run circumferentially out of the ganglion of origin and which give rise to varicose endings in surrounding myenteric ganglia (Bornstein et al,199 I ). A subtype of Dogiel type II neuron, with multiple, short dendritic processes, has also been described (Stach, 1989) and shown to have a different pattern of local projections to other Dogiel type II neurons .…”

Myenteric enkephalin neurons around the laser-photocoagulation necrosis: An immunocytochemical investigation in the guinea pig jejunum and proximal colon.

“…FURNESS et al (1983 b) demonstrated that a majority of enkephalin neurons in the guinea pig small intestine possessed many short processes and a single long process. BORNSTEIN et al (1984) proposed that enkephalin neurons in the guinea pig ileum were all Dogiel's type 1 cells. On the other hand, we were able to show that there were many unclassifiable enkephalin neurons in the guinea pig duodenum and proximal colon (KoBAYASHI et al, 1984(KoBAYASHI et al, , 1985.…”