The influence of salsolinol on dopaminergic system activity within the mediobasal hypothalamus of anestrous sheep: A model for studies on the salsolinol–dopamine relationship

Salsolinol with its derivatives has been considered as a potential neurotoxin for the dopaminergic system in the human and rat brain. Investigating a sheep model for studies on the action of salsolinol within the central nervous system we examined whether this compound is able to affect the hypothalamic neuroendocrine dopaminergic (NEDA) system during its high seasonal activity, when sheep entered to anestrus under the long day conditions. Therefore, salsolinol was infused into the third ventricle of the brain in combination with the in vivo push-pull perfusion of the mediobasal hypothalamus/median eminence (MBH/ME). The effects of this drug on either perfusate noradrenaline (NA) or plasma prolactin concentration were also studied. The infusion of salsolinol resulted in rapid and permanent diminution in dopamine (DA) release into the extracellular spaces of the MBH/ME up to an undetectable level and in the 57% decrease in DA metabolite 3,4- dihydroxyphenylacetic acid concentration, compared to the control. This effect of salsolinol was accompanied by the significant enhancement of the pituitary prolactin release into circulation. The concentration of other DA metabolite, homovanillic acid, as well as NA in the MBH/ME was not affected. Thus, our results in the anestrous sheep underline the role played by salsolinol as a neuromodulator for the hypothalamic NEDA system and as a signal transmitter for the pituitary prolactin release. We suggest that the hypothalamic NEDA system of anestrous sheep during its high secretory activity may be set as a model for studies on the salsolinol-dopamine relationship.