Reduced dopamine synthesis and protein levels in the median eminence of blinded anosmic female rats: relation to the pineal.

Twenty 25 day old female Sprague-Dawley rats were enucleated (BL) and olfactory bulbectomized (ANOS) and one half of these were also pinealectomized (PINX). Ten female rats received no surgical manipulation (CONTROL). Thirty days later each rat received NSD-1015 30 minutes before killing. The median eminence, telencephalon and hypothalamus were collected. Tyrosine hydroxylase activity, determined by the accumulation of DOPA after NSD-1015, was significantly reduced in the median eminence of BL+ANOS (p less than 0.05). Dopamine and noradrenaline levels in this tissue were not different among the experimental groups. Protein levels in the median eminence was also significantly reduced in BL+ANOS and PINX rats. None of the above parameters were different in the hypothalamus among the 3 experimental groups. These data suggest that the activity of the dopaminergic tuberoinfundibular neurons is reduced in both BL+ANOS and PINX rats. The reduced protein may reflect a reduction in protein synthesis, a decrease in numbers of nerve terminals or a reduction of pituitary regulatory hormones in BL+ANOS and PINX rats.