Se. Asmus et Sw. Newman, COLOCALIZATION OF TYROSINE-HYDROXYLASE AND FOS IN THE MALE SYRIAN-HAMSTER BRAIN FOLLOWING DIFFERENT STATES OF AROUSAL, Journal of neurobiology, 25(2), 1994, pp. 156-168
Tn an investigation of the role that central tyrosine hydroxylase- (TH
) containing neurons play in copulation in the male Syrian hamster, th
e induction of Fos protein was used as an index of neuronal activation
. With a double immunoperoxidase technique, the activation of TH neuro
ns was compared in hamsters from three experimental groups: (1) mated
in a new cage; (2) handled controls placed into a new cage, and (3) un
handled controls. Although mating selectively induces Fos production i
n the medial amygdaloid nucleus (Me), more than half of the TH neurons
in Me (a region outside of the classical catecholamine systems) expre
ssed Fos equally in all of the experimental groups. In the paraventric
ular hypothalamic nucleus (PVN), TH neurons were activated equivalentl
y in mated and handled control animals compared to unhandled controls.
TH neurons in the nucleus of the solitary tract (NST) were also activ
ated in handled control animals, and mating further enhanced the level
of Fos immunostaining in these neurons above both groups of nonmated
animals. Although not quantified, co-localization of Fos and TH was al
so observed in all experimental groups in the olfactory bulbs and the
interfascicular nucleus, and in the horizontal limb of the diagonal ba
nd of Broca and the cerebral cortex, regions which contain TH neurons
but are not part of the classically described TH cell groups. Few, if
any, TH neurons in other catecholaminergic brain regions, such as the
substantia nigra and locus coeruleus, produced Fos in any of the exper
imental groups. These results suggest that TH neurons in the PVN and N
ST may be activated during different states of arousal, and that noncl
assical TH neurons in the amygdala produce high levels of Fos even in
unstimulated animals. (C) 1994 John Wiley and Sons, Inc.