Ontogenetic development of the diencephalic MCH neurons: a hypothalamic ‘MCH area’ hypothesis

Abstract

The ontogeny of rat diencephalic melanin-concentrating hormone (MCH) neurons has been analysed, using the bromodeoxyuridine method to determine the period of birth of these neurons, and using in situ hybridization and immunohistochemistry to study their chemical differentiation. The spatiotemporal pattern of MCH neuron generation is complex, although it is broadly lateromedial with a peak between embryonic days (E) 12 and E13. The first expression of the MCH gene has been detected on E13 in neurons in the presumptive lateral hypothalamic area. But the adult-like pattern was observed from E18. Medial-most MCH neurons express the peptide CART (cocaine-amphetamine-regulated transcript) from E18, and the receptor neurokinin 3 (NK3) from between postnatal day (P) 0 and P5. These results are discussed and compared with data from the literature to better understand the organization of the 'MCH-containing area'.

Birthdate of parvalbumin-neurons in the Parvafox-nucleus of the lateral hypothalamus

“…Indeed, the melanin-concentrating hormone (MCH) producing neurons, which form an abundant cell population widespread in the diencephalon and also present in the lateral hypothalamus show a similar spatio-temporal ontogeny also peaking between E12 and E13 (although the MCH-expressing neurons are generated throughout the entire time-period of genesis of the whole hypothalamus, i.e. E10-E17) (Altman and Bayer, 1978;Altman and Bayer, 1986;Amiot et al, 2005;Brischoux et al, 2001;Khachaturian et al, 1985). The hypocretin/orexin positive neurons in the lateral hypothalamus, which are involved in the regulation of sleep/waking states (Chemelli et al, 1999;Nishino et al, 2000;Peyron et al, 2000;Thannickal et al, 2000) and feeding behavior (Qu et al, 1996;Rossi et al, 1997), display also a similar ontogenic pattern.…”

“…The BrdU method used in this study was similar to that already described for the MCH neurons in the hypothalamus (Brischoux et al, 2001).…”

“…The time of conception was documented by spermpositive vaginal smear examined on the morning following the mating night (Embryonic day 0, E0) (Brischoux et al, 2001). …”

“…gestational day (E) 6, 7, 8, 9, 10, 11, 12, 13 and 14 (E6-E14) were given an i.p. injection of 5-bromo-2'-deoxyuridine (BrdU; Roche, Germany) 160 mg/Kg body weight dissolved in 0.9% sterile NaCl, warmed to 60 1C for complete solubilization and filtered before injection (Brischoux et al, 2001;Markakis and Swanson, 1997).…”

Identification of HSP90 as a new GABARAPL1 (GEC1)-interacting protein

“…Rats were anesthetized with an intraperitoneal injection of chloral hydrate 7% (1 ml/200 g), and then perfused as previously described [23] with 0.9% (w/v) NaCl followed by ice-cold 1% (w/v) paraformaldehyde fixative in 0.1 M phosphate buffer. The brains were removed, post-fixed in the same fixative overnight at 4 C, immersed overnight in a 15% (w/v) sucrose solution at 4 C, and then frozen over liquid nitrogen.…”