Hypothalamus perifornical

Figure 2.4 Flip-flop switch model of wake and slow wave sleep active systems. Mutually inhibitory connections exist between GABAergic/Galaninergic slow wave sleep active neurons in the ventrolateral preoptic area (VLPO) of the anterior hypothalamus and aminergic neurons in the hypothalamus (histamine (HA) neurons in the tuberomammillary nucleus (TMN)) and brainstem (serotonin (5-HT) neurons in the dorsal raphe (DR) and noradrenaline (NA) neurons in the locus coeruleus (LC)). Orexinergic neurons in the perifornical hypothalamus (PFH) stabilize the waking state via excitation of the waking side of the flip-flop switch (aminergic neurons).

Lithium has numerous pharmacologic effects. It is able to cross through sodium channels, competing with monovalent and divalent cations in cell membranes (AHFS, 2000). Animal studies have shown that lithium at a serum level of 0.66 + — 0.08 mEq/L can increase the amphetamine-induced release of serotonin (5-hydroxytryptamine [5-HT]) and the concentrations of a serotonin metabolite (e.g., 5-hydroxyindoleacetic acid [5-HIAA]) in the perifornical hypothalamus (PFH) of rats before and after chronic lithium chloride administration (Baptista et ah, 1990), a mechanism possibly involved in lithium s antidepressant effect. The precise neurobiological mechanisms through which lithium reduces acute mania and protects against recurrence of illness remain uncertain (Lenox and Hahn,... 

Currie, PJ. Coscina, D.V (1995) Dissociated feeding and hypothermic effects of neuropeptide Y in the paraventricular and perifornical hypothalamus. Peptides 16, 599-604. 

Methippara, M., Alam, Md. N., Szymusiak, R McGinty, D. (2003). Preoptic area warming inhibits wake-active neurons in the perifornical lateral hypothalamus. 

Narcolepsy, a sleep disorder characterized by excessive daytime sleepiness and cataplexy, may be caused by the lack of hypocretin mRNA and peptides in humans (Peyron et al., 2000) or a disruption of the hypocretin receptor 2 or its ligand in dogs and mice (Lin et al., 1999 Chemelli et al., 1999). Hypocretin-containing neurons are located exclusively in the dorsomedial, lateral, and perifornical hypothalamic areas (Peyron et al., 1998). Two hypocretin sequences, Hcrt-1 (orexin-A) and Hcrt-2 (orexin-B), are generated from a single preprohypocretin (De Lecea et al., 1998 Peyron et al, 1998 Sakurai et al, 1998). Axons from these neurons are found in the hypothalamus, locus coeruleus (LC), raphe nuclei, tuberomamillary nucleus, midline thalamus, all levels of spinal cord, sympathetic and parasympathetic centers, and many other brain regions... 

---