title: Locomotor response to novelty correlates with differences in number and morphology of hypothalamic tyrosine hydroxylase positive cells in rats.
abstract: Individual differences in the intensity of locomotor response to a new environment (exploratory reaction) are generally used as a model to study individual vulnerability to stress and drug addiction. In the present work we studied the number, distribution and morphology of the hypothalamic cells expressing tyrosine hydroxylase (TH+ cells) (immunohistochemical and immunofluorescent staining) in male Wistar rats divided based on high (HR), midline (MR) or low (LR) locomotor activity in response to novelty. Morphology and total number of TH+ cells were analyzed for A11-A15 dopaminergic groups. We found correlation between the total number of hypothalamic TH+ cells in the whole A11-A15 area and the locomotor activity. The differences were most pronounced in some of the hypothalamic nuclei, i.e. in the rostro-caudal extension of the A11, A12 and A14 structures, where the HR rats had a significantly higher number of TH+ cells in comparison to the MR and LR rats. Morphology analysis of TH+ cells showed HR/MR/LR differences in single cell area and perimeter and, to a lesser extent, in the other morphometric parameters such as length of the major and minor axes, or circularity factor. The results suggest that the behavioral traits which characterize the HR animals and are correlated with increased susceptibility to stress and propensity to develop drug addictions can be determined by the number, distribution, activity and perhaps the morphology of the cells in the dopaminergic systems.
authors.affiliation: Department of Animal and Human Physiology, University of Gdansk, 59 Wita Stwosza Street, 80-308 Gdansk, Poland. Electronic address: grajer@wp.pl.
authors.forename: Grażyna
authors.initials: G
authors.lastname: Jerzemowska
authors.affiliation: Department of Animal and Human Physiology, University of Gdansk, 59 Wita Stwosza Street, 80-308 Gdansk, Poland.
authors.forename: Karolina
authors.initials: K
authors.lastname: Plucińska
authors.affiliation: Department of Animal and Human Physiology, University of Gdansk, 59 Wita Stwosza Street, 80-308 Gdansk, Poland.
authors.forename: Magda
authors.initials: M
authors.lastname: Kuśmierczak
authors.affiliation: Department of Animal and Human Physiology, University of Gdansk, 59 Wita Stwosza Street, 80-308 Gdansk, Poland.
authors.forename: Dorota
authors.initials: D
authors.lastname: Myślińska
authors.affiliation: Department of Animal and Human Physiology, University of Gdansk, 59 Wita Stwosza Street, 80-308 Gdansk, Poland.
authors.forename: Jolanta
authors.initials: J
authors.lastname: Orzeł-Gryglewska
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D002452:Cell Count; D059290:Dopaminergic Neurons / Q000166:cytology / Q000378:metabolism; D005106:Exploratory Behavior; D007031:Hypothalamus / Q000166:cytology* / Q000201:enzymology / Q000378:metabolism*; D007150:Immunohistochemistry; D008124:Locomotion; D008297:Male; D009043:Motor Activity; D009483:Neuropsychological Tests; D011597:Psychomotor Performance; D051381:Rats; D017208:Rats, Wistar; D012044:Regression Analysis; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism*
chemical_list: D014446:Tyrosine 3-Monooxygenase
keywords: Dopaminergic neuron morphology; Hypothalamic dopaminergic system; Rats; Response to novelty; Tyrosine hydroxylase