Anatomical interactions of proopiomelanocortin (POMC)-related peptides, neuropeptide Y (NPY) and dopamine beta-hydroxylase (D beta H) fibers and thyrotropin-releasing hormone (TRH) neurons in the paraventricular nucleus of rat hypothalamus.
In order to determine the nature of afferent fibres contacting thyrotropin-releasing hormone (TRH)-synthesizing neuronal cell bodies in the rat hypothalamic paraventricular nucleus, we used dual immunostaining procedures which employed antibodies to ACTH (to label proopiomelanocortin (POMC) neurons), neuropeptide Y (NPY) and dopamine-beta-hydroxylase (D beta H) and peroxidase-labeled goat anti-rabbit IgG as a first sequence and antibodies to a cryptic fragment (Phe178-Glu199) of pro-TRH (to label TRH neurons) and alkaline phosphatase-labeled goat anti-rabbit IgG as the second sequence. A rich innervation of the paraventricular nucleus by immunoreactive POMC, NPY and D beta H fibres was observed. Numerous NPY and POMC fibres were in intimate anatomic proximity and often appeared to surround in remarkable density TRH-containing cell bodies. Less frequent appositions between D beta H fibres and TRH cell bodies were detected. These results strongly suggest that TRH neurons might be regulated by POMC, NPY as well as adrenergic and/or noradrenergic systems. These interactions might be the neuroanatomical basis for the already observed effects of opiate peptides, NPY and catecholamines on TSH secretion.
Liao
N
N
MRC Group in Molecular Endocrinology, Laval University Medical Center, Quebec, Canada.
Bulant
M
M
Nicolas
P
P
Vaudry
H
H
Pelletier
G
G
D000344:Afferent Pathways / Q000033:anatomy & histology / Q000166:cytology; D000818:Animals; D004299:Dopamine beta-Hydroxylase / Q000032:analysis*; D005260:Female; D007124:Immunoenzyme Techniques; D007150:Immunohistochemistry; D009412:Nerve Fibers / Q000201:enzymology / Q000648:ultrastructure; D009474:Neurons / Q000166:cytology* / Q000201:enzymology; D009478:Neuropeptide Y / Q000032:analysis*; D010286:Paraventricular Hypothalamic Nucleus / Q000033:anatomy & histology* / Q000166:cytology / Q000201:enzymology; D011333:Pro-Opiomelanocortin / Q000032:analysis*; D051381:Rats; D011919:Rats, Inbred Strains; D013973:Thyrotropin-Releasing Hormone / Q000032:analysis*
D009478:Neuropeptide Y; D013973:Thyrotropin-Releasing Hormone; D011333:Pro-Opiomelanocortin; D004299:Dopamine beta-Hydroxylase