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Lateralization of opioid receptors in turtle visual cortex
Bakalkin GYa1, A S Pivovarov, A G Kobylyansky
1U.S.S.R. Cardiology Research Center, Academy of Medical Sciences, Moscow.
Brain Research
|February 20, 1989
Summary
Opioid receptors in turtle visual cortex show side-specific functions. Kappa- and mu-receptors modulate the left cortex, while delta-receptors primarily affect the right cortex, indicating selective neurochemical regulation.
Area of Science:
- Neuroscience
- Neuropharmacology
- Opioid Receptor Research
Background:
- Opioid receptors (mu, delta, kappa) are known to modulate neuronal activity.
- The specific roles and distribution of these receptors in different brain regions remain an area of active investigation.
- Understanding receptor function is crucial for developing targeted neuropharmacological treatments.
Purpose of the Study:
- To investigate the differential effects of opioid receptor agonists on evoked potentials in the turtle visual cortex.
- To determine the specific opioid receptor subtypes (mu, delta, kappa, sigma) involved in modulating visual cortex activity.
- To examine the in vivo binding of kappa and delta opioid agonists to the left and right visual cortex.
Main Methods:
- Local application of opioid agonists (morphine, DADL, bremazocine, SKF 10.047) to the surface of the turtle visual cortex.
- Measurement of orthodromic evoked potentials (EP) and their fast negative component (N1).
- In vivo binding studies using radiolabeled kappa ([3H]EKC) and delta ([3H]DADL) agonists on left and right visual cortex membranes.
Main Results:
- Mu-, delta-, and kappa-agonists inhibited the evoked potential (EP), while the sigma-agonist caused inhibition followed by facilitation.
- Morphine and bremazocine predominantly inhibited the left cortical EP, whereas DADL inhibited the right cortical EP.
- In vitro binding showed [3H]EKC and [3H]DADL had higher affinity for left and right visual cortex membranes, respectively.
Conclusions:
- Turtle visual cortex exhibits side-specific opioid receptor modulation of neuronal activity.
- Left visual cortex activity is modulated primarily by kappa- and mu-receptors, while the right is modulated by delta-receptors.
- These findings suggest a neurochemical mechanism for selective regulation of left and right visual cortex activity via distinct opioid receptor populations.