C-PR neuron of Aplysia has differential effects on "Feeding" cerebral interneurons, including myomodulin-positive CBI-12

J Neurophysiol. 1999 Feb;81(2):521-34. doi: 10.1152/jn.1999.81.2.521.

Abstract

Head lifting and other aspects of the appetitive central motive state that precedes consummatory feeding movements in Aplysia is promoted by excitation of the C-PR neuron. Food stimuli activate C-PR as well as a small population of cerebral-buccal interneurons (CBIs). We wished to determine if firing of C-PR produced differential effects on the various CBIs or perhaps affected all the CBIs uniformly as might be expected for a neuron involved in producing a broad undifferentiated arousal state. We found that when C-PR was fired, it produced a wide variety of effects on various CBIs. Firing of C-PR evoked excitatory input to a newly identified CBI (CBI-12) the soma of which is located in the M cluster near the previously identified CBI-2. CBI-12 shares certain properties with CBI-2, including a similar morphology and a capacity to drive rhythmic activity of the buccal-ganglion. Unlike CBI-2, CBI-12 exhibits myomodulin immunoreactivity. Furthermore when C-PR is fired, CBI-12 receives a polysynaptic voltage-dependent slow excitation, whereas, CBI-2 receives relatively little input. C-PR also polysynaptically excites other CBIs including CBI-1 and CBI-8/9 but produces inhibition in CBI-3. In addition, firing of C-PR inhibits plateau potentials in CBI-5/6. The data suggest that activity of C-PR may promote the activity of one subset of cerebral-buccal interneurons, perhaps those involved in ingestive behaviors that occur during the head-up posture. C-PR also inhibits some cerebral-buccal interneurons that may be involved in behaviors in which C-PR activity is not required or may even interfere with other feeding behaviors such as rejection or grazing, that occur with the head down.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Aplysia
  • Cell Size / physiology
  • Central Nervous System / physiology*
  • Evoked Potentials / physiology
  • Feeding Behavior / physiology*
  • Ganglia, Invertebrate / physiology
  • In Vitro Techniques
  • Interneurons / cytology
  • Interneurons / metabolism
  • Interneurons / physiology*
  • Neural Inhibition / physiology
  • Neural Pathways / physiology
  • Neurons / cytology
  • Neurons / physiology*
  • Neuropeptides / metabolism*
  • Patch-Clamp Techniques

Substances

  • Neuropeptides
  • myomodulin