The effects of local microinjection of selective dopamine D1 and D2 receptor agonists and antagonists into the dorsal raphe nucleus on sleep and wakefulness in the rat.

The effects of the dopamine (DA) D1 and D2 receptor agonists SKF38393, bromocriptine and quinpirole, respectively, on spontaneous sleep were analyzed in adult rats prepared for chronic sleep recordings. Local administration of the DAergic agonists into the dorsal raphe nucleus (DRN) during the light phase of the light-dark cycle induced a significant reduction of rapid-eye movement sleep (REMS) and the number of REM periods. Additionally, bromocriptine and quinpirole significantly increased wakefulness (W).

Microinjection of the melanin-concentrating hormone into the sublaterodorsal tegmental nucleus inhibits REM sleep in the rat.

A study was performed on the effects of local microinjection of melanin-concentrating hormone (MCH) into the right sublaterodorsal tegmental nucleus (SLD) on sleep and wakefulness in rats prepared for chronic sleep recordings. MCH 200ng significantly decreased rapid-eye-movement sleep (REMS) time during the first and second 2-h of the recording period which was related to the reduction of the number of REMS periods and the increase of REMS latency. It is proposed that REMS inhibition was related to the direct deactivation of SLD glutamatergic neurons by the peptide.

The effects of systemic administration and local microinjection into the central nervous system of the selective serotonin 5-HT2C receptor agonist RO-600175 on sleep and wakefulness in the rat.

The effects of RO-600175, a selective 5-HT2C receptor agonist, were studied in adult rats implanted for chronic sleep recordings. Intraperitoneal administration of RO-600175 (4 mg/kg) during the light phase of the light-dark cycle significantly increased wakefulness and reduced slow wave sleep and rapid-eye-movement sleep during the first 2 h of the recording period. Direct infusion of RO-600175 into the dorsal raphe nucleus (4 mmol/l), laterodorsal tegmental nucleus (4 mmol/l), or horizontal limb of the diagonal band of Broca (4 mmol/l) also decreased rapid-eye-movement sleep.

Increased REM sleep after intra-locus coeruleus nucleus microinjection of melanin-concentrating hormone (MCH) in the rat.

A study was carried out on the effects of unilateral microinjection of melanin-concentrating hormone (MCH) into the right locus coeruleus (LC) on the sleep-wake cycle in rats prepared for chronic sleep recordings. MCH 200 ng significantly augmented rapid-eye-movement sleep (REMS) time during the first, second and third 2-h of recording. Furthermore, MCH 100 ng induced a significant increase of REMS during the first 2-h period after treatment.

The role of serotonin 5-HT7 receptor in regulating sleep and wakefulness.

Different approaches have been followed to characterize the role of 5-hydroxytryptamine (serotonin) receptor 7 (5-HT7) in the regulation of sleep-wake behavior: (1) 5-HT7 receptor knockout mice spend less time in rapid eye movement sleep than their wild-type counterparts, mainly during the light period. In contrast, there is no difference between the genotypes in time spent in wakefulness or slow-wave sleep. (2) Systemic administration of the selective 5-HT7 receptor agonist LP-211 significantly increased wakefulness (time spent awake) and reduced rapid eye movement sleep in the rat.