Effect of monoamine neurotransmitters in the hypothalamus in a cortisol-induced rat model of yang-deficiency

Eight monoamine neurotransmitters in hypothalamus of normal and cortisol-induced Yang-deficiency rats were measured with HPLC-ECD. These neurotransmitters included: (1) Noradrenaline (NA); (2) Adrenaline (A); (3) 3-methoxy-4-hydroxyphenyl glycol (MHPG); (4) 3,4-dihydroxyphenylacetic acid (DOPAC); (5) Dopamine (DA); (6) 5-hydroxyindole-3-acetic acid (5-HIAA); (7) Homovanillic acid (HVA); and (8) Serotonin (5-HT). With the mobile phase of 10% methanol-0.15 M chloroacetic acid-sodium hydroxide buffer, the neurotransmitters might be well separated, the sensitivity was similar to that of gas chromatography-mass spectrogram with the lower limit of 0.1 ng, this assay was simple and might be accomplished with half an hour. The Yang-strengthening Chinese herbs Radix Aconiti Praeparata, Cortex, Cinamomi, Epimedium brevicorum and Herba Cistanchis were used in the study and the following were founded: (1) In the hypothalamus of cortisol-induced Yang-deficiency rat NA decreased and a increased when compared with that of the normal controls (both P less than 0.05). (2) After 4 weeks of administration of Yang-strengthening herbs, the NA and A of the Yang-deficiency rats returned to nearly normal and it suggested these herbs have the effect of "supporting the right and recovering the source"; DA markedly increased both in control rats and Yang-deficiency rats (P less than 0.05, P less than 0.001 respectively); DOPAC obviously decreased both in control rats and Yang-deficiency rats (P less than 0.001); 5-HT and 5-HIAA increased in the control rats (both P less than 0.001) and HVA significantly decreased in Yang-deficiency rats. (3) The ratio of DA/DOPAC and 5-HT/5-HIAA markedly increased both in the control and Yang-deficiency rats after using Yang-strengthening herbs (P less than 0.01-0.001) and it suggested Yang-strengthening herbs could inhibit the activity of monoamine oxidase in hypothalamus.