DISSOCIATION BETWEEN ADRENAL TYROSINEHYDROXYLASE AND PHENYLETHANOLAMINE N-METHYLTRANSFERASE ACTIVITIES FOLLOWING REPEATED EXPERIENCE OF DEFEATS IN INDIVIDUALLY HOUSED MALE DBA 2J MICE/
A. Haemisch et K. Gartner, DISSOCIATION BETWEEN ADRENAL TYROSINEHYDROXYLASE AND PHENYLETHANOLAMINE N-METHYLTRANSFERASE ACTIVITIES FOLLOWING REPEATED EXPERIENCE OF DEFEATS IN INDIVIDUALLY HOUSED MALE DBA 2J MICE/, Physiology & behavior, 59(6), 1996, pp. 1117-1122
Adrenal activities of tyrosnehydroxylase (TH) and phenylethanolamine N
-methyltransferase (PNMT) were compared between individually housed de
feated intruders and socially housed residents (SR) (Experiment 1), an
d between individually housed defeated intruders and individually hous
ed victor residents (Experiment 2). In addition, corticosterone titers
were determined and dominance status of SR (dominant, subdominant act
ive, and subdominant passive) considered. Defeats were induced twice a
week for 6 consecutive weeks in short resident-intruder encounters. T
he main findings were: 1) within the groups of SR, TH and PNMT activit
ies were high in dominant and low in subdominant-passive mice; 2) in E
xperiment 1, TH activities of individually housed defeated intruders w
ere low like those of subdominant-passive SR whereas their PNMT activi
ties were high like those of dominant SR; 3) in Experiment 2, TH activ
ities were low in both categories of individually kept mice whereas PN
MT activities were significantly elevated in the defeated intruders; 4
) in both experiments, PNMT activities of intruders correlated signfic
antly with the accumulated number of attacks they had received through
out all resident-intruder tests. Findings show separate effects of per
manent social stimulation and of episodic experience of defeats on adr
enal catecholamine synthesis. Lack of permanent social stimulation dec
reased adrenal TH and PNMT activities whereas repeated episodic experi
ence of defeats specifically increased PNMT but not TH activities in i
ndividually housed mice.