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CRF-like immunoreactivity selectively labels preganglionic sudomotor neurons in cat
A D Shafton1, B J Oldfield, R M McAllen
1Howard Florey Institute of Experimental Physiology and Medicine, University of Melbourne, Parkville, Vic., Australia.
Brain Research
|December 25, 1992
Summary
Preganglionic sympathetic neurons containing corticotrophin releasing factor-like immunoreactivity (CRF-LI) primarily innervate cholinergic neurons in cats. These CRF-LI neurons are predominantly sudomotor, controlling sweat gland function.
Area of Science:
- Neuroscience
- Autonomic Nervous System Research
- Mammalian Physiology
Background:
- Preganglionic sympathetic neurons utilize various neurotransmitters to regulate postganglionic neuron activity.
- Corticotropin-releasing factor-like immunoreactivity (CRF-LI) has been identified in specific preganglionic sympathetic neurons, but their targets remain incompletely understood.
- Understanding the precise innervation patterns is crucial for deciphering autonomic control mechanisms.
Purpose of the Study:
- To identify the specific type of postganglionic sympathetic neuron innervated by preganglionic neurons containing CRF-LI in cats.
- To determine the functional role of preganglionic sympathetic neurons expressing CRF-LI.
Main Methods:
- Immunohistochemistry was employed to detect CRF-LI and tyrosine hydroxylase-like immunoreactivity (TH-LI) in feline sympathetic ganglia.
- Neuronal tracing techniques, including the use of calcitonin gene-related peptide (CGRP)-LI and retrograde tracer fluorogold, were utilized.
- Quantitative analysis of CRF-LI terminal baskets and their association with specific neuronal populations was performed.
Main Results:
- Preganglionic neurons with CRF-LI terminate in the stellate and lumbar ganglia, surrounding primarily presumptive cholinergic neurons (lacking TH-LI).
- Cholinergic neurons innervating sweat glands (identified by CGRP-LI) were extensively surrounded by CRF-LI terminal baskets (81-86%).
- Retrograde tracing revealed that 26-38% of neurons projecting to paw pads were innervated by CRF-LI terminals, suggesting a mixed population.
Conclusions:
- In cats, preganglionic sympathetic neurons expressing CRF-LI predominantly target cholinergic neurons.
- The findings strongly indicate that CRF-LI preganglionic sympathetic neurons are primarily sudomotor in function, regulating sweat secretion.