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Spontaneous multiple unit activity from the preoptic nucleus and changes in blood pressure in the rainbow trout Salmo
Abstract:
Multiple unit activity (MUA) from the preoptic nucleus (NPO) blood pressure and heart rate were recorded in 41 anaesthetized and curarized rainbow trout. Mayer waves were frequently observed in blood pressure recordings (83%). Rhythmic MUA from the NPO, recorded in 46% of the experimented trout, occurred preferentially during Mayer waves. The initiation of the period of MUA occurred during low pressure vasomotor tone and large vasomotor pulse pressure inhibited MUA. Sustained decrease in blood pressure induced proportional rise in MUA. These results suggest that cardiovascular inputs influence the electrical activity of neurosecretory cells within the NPO and so may modulate the neurohypophysial hormones secretion.
Insights
Cardiovascular changes, like Mayer waves, influence neural activity in the preoptic nucleus (NPO) of trout. This suggests blood pressure regulation may affect neurosecretory cell function and hormone release.
Area of Science:
- Neuroscience
- Cardiovascular Physiology
- Fish Biology
Background:
- The preoptic nucleus (NPO) plays a role in regulating autonomic functions.
- Mayer waves, oscillations in blood pressure, are indicative of baroreceptor reflex activity.
- Understanding the interplay between cardiovascular signals and neural activity is crucial for comprehending homeostatic mechanisms.
Purpose of the Study:
- To investigate the relationship between cardiovascular activity and neural electrical activity in the trout preoptic nucleus (NPO).
- To determine if Mayer waves influence neuronal firing patterns within the NPO.
- To explore the potential impact of cardiovascular inputs on neurosecretory cell function in the NPO.
Main Methods:
- Recording of multiple unit activity (MUA) from the NPO in anesthetized and curarized rainbow trout.
- Simultaneous monitoring of blood pressure and heart rate.
- Analysis of MUA patterns in relation to observed Mayer waves and blood pressure fluctuations.
Main Results:
- Mayer waves were frequently observed in blood pressure recordings (83% of trout).
- Rhythmic MUA from the NPO was recorded in 46% of trout, preferentially occurring during Mayer waves.
- MUA initiation coincided with low blood pressure, while high pulse pressure inhibited MUA; decreased blood pressure led to increased MUA.
Conclusions:
- Cardiovascular inputs, specifically blood pressure variations and Mayer waves, significantly influence the electrical activity of neurosecretory cells in the trout NPO.
- These findings suggest a mechanism by which the cardiovascular system may modulate the secretion of neurohypophysial hormones.
- The study highlights the integration of cardiovascular and neuroendocrine functions in fish.