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Perifornical fiber system mediates VMH electrically-induced suppression of feeding
Abstract:
Fiber pathways mediating the cessation of food ingestion during continuous low-level electrical stimulation of the ventromedial region of the hypothalamus (VMH) were appraised in food-deprived male rats using knife cuts. Parasagittal knife cuts in the medial perifornical area of the hypothalamus produced much larger increases in threshold current intensities for the inhibition of feeding than did cuts in the lateral perifornical hypothalamus. These findings indicate that fiber pathways critical to the inhibitory feeding effect of continuous VMH electrical stimulation traverse the perifornical hypothalamus but not the lateral hypothalamus. A comparison of these and other results demonstrates an anatomical similarity between the fiber pathways mediating VMH electrically-induced inhibition of feeding and hypothalamic hyperphagia following lesions or knife cuts. The nature of the inhibitory feeding effect of VMH electrical stimulation is also addressed and behavioral observations strongly supportive of a specific anorectic effect produced by the stimulation are reported.
Insights
Electrical stimulation of the ventromedial hypothalamus (VMH) inhibits feeding. Critical fiber pathways for this effect run through the perifornical hypothalamus, not the lateral hypothalamus, in male rats.
Area of Science:
- Neuroscience
- Behavioral Neuroscience
- Physiology
Background:
- The ventromedial hypothalamus (VMH) plays a crucial role in regulating food intake.
- Electrical stimulation of the VMH can inhibit feeding behavior.
- Understanding the neural pathways involved is key to comprehending appetite regulation.
Purpose of the Study:
- To identify the specific fiber pathways mediating the food intake inhibition caused by VMH electrical stimulation.
- To compare these pathways with those involved in other hypothalamic feeding-related processes.
Main Methods:
- Utilized knife cuts in specific hypothalamic regions (medial and lateral perifornical areas) of food-deprived male rats.
- Assessed changes in the threshold current intensity required to inhibit feeding during VMH stimulation.
Main Results:
- Parasagittal knife cuts in the medial perifornical hypothalamus significantly increased the current intensity needed to inhibit feeding.
- Cuts in the lateral perifornical hypothalamus had a lesser effect on the feeding inhibition threshold.
- Identified critical fiber pathways for VMH stimulation's inhibitory effect traversing the perifornical hypothalamus.
Conclusions:
- Fiber pathways essential for VMH electrical stimulation-induced feeding cessation are located within the perifornical hypothalamus.
- These pathways share anatomical similarities with those implicated in hypothalamic hyperphagia.
- VMH electrical stimulation appears to exert a specific anorectic effect.