Abstract

Anatomical organization of GAD67 and calcium-binding protein mRNA in the human hypothalamus.

D. M. KROLEWSKI; A. MEDINA; I. A. KERMAN; R. BERNARD; S. BURKE; E. G. JONES; W. E. BUNNEY; H. AKIL; S. J. WATSON
Society for Neuroscience. 2009.

Abstract

The hypothalamus utilizes a collection of neuroactive substances to regulate autonomic behaviors related to stress, sleep, and feeding. Though much is known regarding the local anatomical relationship between these molecules in rodent, less is known in humans. In an effort to overcome this problem, previous experiments in our lab were conducted to generate comprehensive neurochemical maps of the human hypothalamus which detail the specific localization of arginine-vasopressin (AVP), histamine decarboxylase (HDC), melanin-concentrating hormone (MCH), and orexin (ORX). In the current study, we used these nuclear defining maps as a template to investigate the local gene expression patterns for the gamma-aminobutryic acid (GABA) synthesizing enzyme GAD67 and calcium-binding proteins calretinin (CR), calbindin (CB), and parvalbumin (PV). Methods: In-situ hybridization (ISH) experiments with 35scRNA probes for AVP, HDC, MCH, ORX, GAD67, CR, and CR were performed on adjacent 10um thick hypothalamic sections obtained from freshly frozen human brain. Sections were developed on imaging film, scanned, and subsequently captured digitized images were overlaid in Adobe® Photoshop® CS8.0. Results: Amongst our findings, we show that there is little overlap of AVP with GAD67, CR, or CB in the paraventricular nucleus. GAD67 mRNA expression well defines the periventricular nucleus whereas CR and CB delineate the ventromedial nucleus. Throughout the tuberomamillary complex, HDC expression is closely paralleled by that of GAD67, but not CR and CB. Within the dorsomedial and perifonical area, ORX mRNA overlap with GAD67, CR, and CB was weak. In the more posterior hypothalamus, there was strong co-regional expression of MCH, GAD67, CR, and CB in the dorsal hypothalamic area whereas PV mRNA was isolated to the mammillary bodies. Conclusion: The present study advances the understanding of the biochemical heterogeneity in the human hypothalamus. These results will further be discussed in relation to major depressive disorders.