Hypophysectomy-induced striatal hypersensitivity and mesolimbic hyposensitivity to apomorphine.
Seven days post-hypophysectomy female rats display a hyposensitivity to the locomotor effects of apomorphine and a hypersensitivity to the stereotypy effects of apomorphine, while at 28 days post-hypophysectomy they are hypersensitive to both the locomotor and stereotypy effects of apomorphine. The hyposensitivity to the locomotor effects, at 7 days post-hypophysectomy, was associated with a decrease in 3H-spiroperidol binding and an increase in tyrosine hydroxylase activity in the nucleus accumbens septi, whereas the hypersensitivity, at 28 days post-hypophysectomy, was associated with an increase in 3H-spiroperidol and a decrease in tyrosine hydroxylase activity in the n. accumbens septi. The increased apomorphine-induced stereotypy in both the 7 and 28 days post-hypophysectomized animals was related to an increased 3H-spiroperidol binding and a decreased tyrosine hydroxylase activity in the striatum. These behavioral and neurochemical data demonstrate that following hypophysectomy female rats will develop a transient decrease in dopamine receptor sensitivity in the n. accumbens septi, while the dopamine sensitivity in the striatum is increased. Thus the hypophysectomized female rat may prove to be a valuable model to study these two separate dopamine systems and their possible modulatory roles in the display of various behaviors.
D000818:Animals; D001058:Apomorphine / Q000494:pharmacology*; D003342:Corpus Striatum / Q000201:enzymology / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D005260:Female; D005968:Glutamate Decarboxylase / Q000378:metabolism; D006801:Humans; D007016:Hypophysectomy; D009043:Motor Activity / Q000187:drug effects / Q000502:physiology; D009714:Nucleus Accumbens / Q000201:enzymology / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D011954:Receptors, Dopamine / Q000378:metabolism; D012686:Septal Nuclei / Q000502:physiology*; D013239:Stereotyped Behavior / Q000187:drug effects* / Q000502:physiology; D013378:Substantia Nigra / Q000201:enzymology / Q000502:physiology*; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism
D011954:Receptors, Dopamine; C031611:spiroperidol receptor; D014446:Tyrosine 3-Monooxygenase; D005968:Glutamate Decarboxylase; D001058:Apomorphine