Systems neuroscienceHypothalamic and zona incerta neurons expressing hypocretin, but not melanin concentrating hormone, project to the hamster intergeniculate leaflet
Section snippets
Animals
Adult, outbred male golden hamsters (Charles River, Wilmington, MA, USA) were maintained with free access to food and water under a 14-h light/10-h dark photoperiod in individual, polypropylene cages. All experimental procedures were approved by the Institutional Animal Care and Use Committee of Stony Brook University. Care was taken to use the least number of animals possible and to minimize their discomfort. All experimental procedures were approved by the Institutional Animal Care and Use
Injection sites
Brains that received injections centered in the IGL (n=11) with minimal spread to adjacent structures were chosen for analysis (Fig. 1). Typical injection sites were centered in the medial aspect of the mid-caudal IGL with very little functional spread into the dorsal lateral geniculate nucleus and almost no spread into the ventral lateral geniculate. Successful CTB injections to the IGL were further verified by the presence of retrogradely labeled neurons in the pretectum and contralateral IGL
Discussion
An Hcrt-ir terminal plexus has been reported in the hamster IGL (Mintz et al., 2001). The present data confirm this projection and identify the cells of origin which are located in the ZIM and LH. The data also show the anatomical distribution of MCH-ir cells in the hamster hypothalamus and their relationship to Hcrt-ir and IGL projecting cells. The results demonstrate that, as in the rat (Broberger et al 1998, Elias et al 1998), Hcrt- and MCH-ir neurons have overlapping distributions in the
Acknowledgment
The authors wish to thank Dr. Seth Horowitz for his assistance with earlier versions of the manuscript. Grant Sponsor: National Institute of Mental Health; Grant Number MH6447101. Grant Sponsor: National Institute of Neurological Disease and Stroke; Grant Number NS22168.
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Drugs that prevent mouse sleep also block light-induced locomotor suppression, circadian rhythm phase shifts and the drop in core temperature
2013, NeuroscienceCitation Excerpt :Antle et al. (2001) suggest that sleep-modulatory adenosine R1 agonists could alter the circadian clock via serotonin release from the intergeniculate leaflet (IGL)-afferent dorsal raphe projection (Meyer-Bernstein and Morin, 1996). It is also possible that orexin/hypocretin neurons contributing to sleep/arousal regulation modify circadian rhythm function via input to the IGL (Vidal et al., 2005). A circuit by which nocturnal light might induce sleep consists of retinal projections to the SCN, rhythmic output from the SCN to the paraventricular thalamus, and passage of that output from there, rostrally to the nucleus accumbens (Krettek and Price, 1977; Moga et al., 1995; Yamazaki et al., 1998; Pinto et al., 2003; Sleipness et al., 2007; Qiu et al., 2010, 2012; Morin, 2013a).
Cellular location and major terminal networks of the orexinergic system in the brain of two megachiropterans
2013, Journal of Chemical NeuroanatomyCitation Excerpt :The orexinergic neurons of the mammalian hypothalamus generally form three distinct clusters, a main cluster located in the perifornical, dorsomedial and lateral hypothalamic regions, a zona incerta cluster located adjacent to and within the zona incerta, and an optic tract cluster located in the ventrolateral hypothalamus near the optic tract. While variations on this general nuclear parcellation of orexinergic neurons are apparent, such as the additional parvocellular cluster in the cetartiodactyls (Dell et al., 2012) and the absence of the optic tract cluster in the microchiropterans and hamsters (Mintz et al., 2001; McGranaghan and Piggins, 2001; Khorooshi and Klingenspor, 2005; Vidal et al., 2005; Kruger et al., 2010a), it would appear that the phylogenetic plasticity in terms of the parcellation of this system is less labile than many other neural systems. The terminal networks of the orexinergic systems are found throughout the brain, but in different densities in various locations (see references listed above), and these terminal networks show a similar consistency in location when comparing across mammalian species.
Neuroanatomy of the extended circadian rhythm system
2013, Experimental Neurology