dc.description.abstract | Abstract Mechanisms underlying sex-related differ
ences in adaptation to high altitude were investigated by
assessing the turnover of dopamine and noradrenaline in
structures of the chemoafferent pathway, i.e. carotid
body and brainstem noradrenergic cell groups (A1, A5,
A
6, A2 to which chemosensory fibres project). The influ
ence of gender was assessed in male and female rats
reared at an altitude of 3600 m, whereas the influence of
endogenous sex hormones was evaluated by castration.
Haematocrit, red blood cell count and plasma erythropoi
etin levels were lower in females than in males (–5%,
–15%, –53%, respectively). Dopamine and noradrenaline
turnover were higher in female structures (carotid body:
+51%; A2: +140%; A1: +54%; A5: +27%). Dopamine
and noradrenaline turnover in carotid body and brain
stem cell groups were differently affected by castration,
i.e. enhanced by orchidectomy (carotid body: +134%;
A
2: +120%; A1: +69%; A5: +67%) but inhibited by ovar
iectomy (carotid body: –33%; A2: –92%). Orchidectomy
elicited a reduction in haematocrit (–10%), haemoglobin
concentration (–8%) and red blood cell count (–24%),
whereas haematological status remained unaltered after
ovariectomy. Therefore, both gender and endogenous sex
steroids may control catecholamine activity differently in
structures involved in the chemoafferent pathway, thus
providing a neurochemical basis for sex-related differ
ences in adaptation to hypoxia. | |