Melanin-concentrating hormone is expressed in the laterodorsal tegmental nucleus only in female rats.
Melanin-concentrating hormone (MCH) is a neuropeptide originating from prepro-MCH. In male rats, neurons expressing MCH are found in the lateral hypothalamic area and medial zona incerta, as well as, sparsely, in the olfactory tubercle and pontine reticular formation. The wide distribution of MCH fibers suggests the involvement of this neuropeptide in a variety of functions, including arousal, neuroendocrine control and energy homeostasis. In lactating females, MCH is expressed in the preoptic area, indicating sexual dimorphism in MCH gene activation according to the female reproductive state. We hypothesized that MCH is also expressed differentially in the brainstem of female rats. Adult male rats and female rats (in the afternoon of diestrus and proestrus days; ovariectomized; or on lactation days 5, 12 and 19) were perfused between 2 and 4 p.m., and the brainstems were processed for in situ hybridization using a 35S-labeled prepro-MCH riboprobe. As described in males, prepro-MCH was expressed in the pontine reticular formation of females. We also observed consistent prepro-MCH expression in the caudal laterodorsal tegmental nucleus (LDT) of females but no differential expression comparing the various female reproductive states. Using dual-label immunohistochemistry or dual-label in situ hybridization, we found that brainstem MCH neurons coexpress glutamic acid decarboxylase mRNA, the gamma aminobutyric acid (GABA) processing enzyme, but do not colocalize choline acetyl transferase (acetylcholine processing enzyme). Since changes in LDT GABAergic cell activity are associated with rapid eye movement (REM) sleep, our findings suggest that MCH interacts with LDT GABAergic neurons and plays a role in REM sleep regulation.
Rondini
Tatiane Araujo
TA
Laboratory of Chemical Neuroanatomy, Department of Anatomy, Institute of Biomedical Sciences, University of São Paulo, 05508-900 São Paulo, SP, Brazil.
Rodrigues
Bruno de Crudis
Bde C
de Oliveira
Anne Pierre
AP
Bittencourt
Jackson Cioni
JC
Elias
Carol Fuzeti
CF
D000818:Animals; D004031:Diestrus / Q000378:metabolism; D005260:Female; D015870:Gene Expression / Q000502:physiology*; D005968:Glutamate Decarboxylase / Q000235:genetics / Q000378:metabolism; D007028:Hypothalamic Hormones / Q000235:genetics / Q000378:metabolism*; D017403:In Situ Hybridization / Q000379:methods; D007773:Lactates / Q000378:metabolism; D008297:Male; D008543:Melanins / Q000235:genetics / Q000378:metabolism*; D010052:Ovariectomy / Q000379:methods; D045042:Pedunculopontine Tegmental Nucleus / Q000378:metabolism*; D010907:Pituitary Hormones / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012727:Sex Characteristics; D013997:Time Factors
D007028:Hypothalamic Hormones; D007773:Lactates; D008543:Melanins; D010907:Pituitary Hormones; C019463:melanin-concentrating hormone; D005968:Glutamate Decarboxylase; C402565:glutamate decarboxylase 1