Effect of noradrenergic denervation of medial prefrontal cortex and dentate gyrus on recovery after sleep deprivation in the rat.

The noradrenergic-locus coeruleus (LC) system has a regulatory influence on forebrain neuronal networks. We have previously shown that the amygdala is strongly implicated in the mechanism of rebound seen after a 10 h sleep deprivation (SD). In the present study, our objective was to determine whether the medial prefrontal cortex and dentate gyrus (DG) which receive an important innervation from the LC, play a role in the rebound mechanisms.

Effect of noradrenergic denervation of the amygdala upon recovery after sleep deprivation in the rat.

We previously showed that the noradrenergic locus coeruleus (NA-LC) was involved in the regulatory mechanisms of the paradoxical sleep rebound following a 10 h sleep deprivation by using a systemic injection of a specific neurotoxin, N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4). Given that rebound mechanisms are mainly located in the forebrain, we planned to study the role of the forebrain structures receiving LC afferences. In this study we evaluated the involvement of noradrenergic afferences to the central nucleus of the amygdala in the sleep rebound by DSP-4 microinjections into the central nucleus of the rat amygdala.

Hypoprolactinemic rats under conditions of constant darkness or constant light. Effects on the sleep-wake cycle, cerebral temperature and sulfatoxymelatonin levels.

In genetic hypoprolactinemic rats under light-dark (LD) conditions, the circadian rhythms of slow-wave (SWS) and paradoxical (PS) sleep display an alteration of their phase relationship. The aim of our study was to investigate the effects of constant darkness (DD) or constant light (LL) on the daily distribution and amounts of sleep-wake stages, cerebral temperature and concentrations of the urinary melatonin metabolite, 6-sulfatoxymelatonin, in prolactin-deficient rats. After 3 weeks of DD, the SWS period was 24 h 8+/-6 min and the acrophase occurred at 15:44+/-1:35, while for PS, the period was more stable than during LD (24 h 10+/-8 min vs.

Distribution of prolactin receptors in the rat forebrain. Immunohistochemical study.

The distribution of prolactin receptors (PRL-R) in the rat brain was investigated for the first time with the immunohistochemical technique using monoclonal antibodies raised against PRL-R purified from rat liver. Granular immunostaining was observed in neurons and along their dendritic processes and fibers. PRL-R like immunoreactive neurons were found in a number of brain areas.

Hypothalamic injection of prolactin or its antibody alters the rat sleep-wake cycle.

Several studies have suggested an interaction between prolactin and the sleep-wake cycle. In this study ovine prolactin (oPRL) and anti-prolactin antibody were microinjected into the rat dorsolateral hypothalamus, which contains prolactin-like immunoreactive neurons. Results indicate that during the light period, prolactin injection induced an increase in paradoxical sleep duration, whereas it caused a decrease when injected during the dark period.

Anatomical distribution of prolactin-like immunoreactivity in the rat brain.

The present study examines prolactin PRL-like immunoreactivity (PRL-LIR) in the rat central nervous system and describes the distribution of labeled perikarya and fibers using a specific antiserum to ovine PRL. This antiserum does not cross-react with molecules of the pro-opiomelanocortin (POMC) family and recognizes rat PRL. PRL-LIR cell bodies are found exclusively in the lateral hypothalamic area surrounding the fornix, especially dorsolateral to it.

[Demonstration of prolactin messenger RNA after amplification in the brain in rats].

By means of immunocytochemistry, a central neuronal network containing a prolactin-like substance has been described in the rat. In order to demonstrate the synthesis of this peptide in these cells, we examined the presence of prolactin messenger RNA (PRL mRNA) in several brain samples including the pituitary gland. Amplification of the PRL mRNA was performed by the polymerase chain reaction technique, followed by southern blotting and hybridization with a specific oligonucleotide.

[Prolactin-secreting neurons in the dorsolateral hypothalamus in Sprague-Dawley rats].

By means of immunocytochemical techniques ovine prolactin like immunoreactivity (oPRL-LIR) has been demonstrated in the perikarya located around fornix in the dorso-lateral part of the rat hypothalamus. No PRL-LIR was observed in the arcuate n. perikarya.