The anterolateral projections of the medial basal hypothalamus affect sleep

Feb 6, 2009American journal of physiology. Regulatory, integrative and comparative physiology

Sleep is influenced by signals from the front-side area of the brain’s medial basal hypothalamus

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Abstract

Severing both lateral and anterior connections of the medial basal hypothalamus (MBH) led to a reduction in non-rapid eye movement sleep (NREMS) and rapid eye movement sleep (REMS) in rats.

Rats with severed lateral and anterior MBH connections spent less time in both NREMS and REMS.
Maintaining lateral connections resulted in normal durations of NREMS and REMS.
All groups except the sham control exhibited altered diurnal rhythms of NREMS and REMS.
No changes in NREMS or REMS duration were observed in rats with pituitary stalk lesions.
Enhanced water consumption was noted in three groups, potentially linked to the loss of vasopressin fibers.
EEG delta power and brain temperature were not affected by MBH connection severance.

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The role of the medial basal hypothalamus (MBH) and the anterior hypothalamus/preoptic area (AH/POA) in sleep regulation was investigated using the Halász knife technique to sever MBH anterior and lateral projections in rats. If both lateral and anterior connections of the MBH were cut, rats spent less time in non-rapid eye movement sleep (NREMS) and rapid eye movement sleep (REMS). In contrast, if the lateral connections remained intact, the duration of NREMS and REMS was normal. The diurnal rhythm of NREMS and REMS was altered in all groups except the sham control group. Changes in NREMS or REMS duration were not detected in a group with pituitary stalk lesions. Water consumption was enhanced in three groups of rats, possibly due to the lesion of vasopressin fibers entering the pituitary. EEG delta power during NREMS and brain temperatures (Tbr) were not affected by the cuts during baseline or after sleep deprivation. In response to 4 h of sleep deprivation, only one group, that with the most anterior-to-posterior cuts, failed to increase its NREMS or REMS time during the recovery sleep. After deprivation, Tbr returned to baseline in most of the treatment groups. Collectively, results indicate that the lateral projections of the MBH are important determinants of duration of NREMS and REMS, while more anterior projections are concerned with the diurnal distribution of sleep. Further, the MBH projections involved in sleep regulation are distinct from those involved in EEG delta activity, water intake, and brain temperature.

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The anterolateral projections of the medial basal hypothalamus affect sleep

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