Changes in dopamine activity in the zona incerta (ZI) over the rat oestrous cycle and the effect of lesions of the ZI on cyclicity: further evidence that the incerto-hypothalamic tract has a stimulatory role in the control of LH release.
Previous results indicate that the dopaminergic system in the anterior medial zona incerta (ZI) exerts a stimulatory effect on LH release. In this report changes in dopamine (DA) turnover in the ZI, preoptic area (POA) and arcuate/median eminence area (ARC/ME) (as assessed by the rate of decline in DA concentration after alpha-methyl-p-tyrosine) have been noted each afternoon (16.00-18.00 h) of the 4 days of the oestrous cycle and also on the morning (9.00-11.00 h) of proestrus (P) and second day of dioestrus (D2). Over the time of the preovulatory LH surge on P, a significant rise in DA turnover was observed in the ZI. As this area contains components of the dopaminergic incerto-hypothalamic (I-H) tract, this study provides evidence to implicate the I-H tract in the physiological stimulation of the preovulatory surge of LH on proestrus. Selective destruction of DA nerve terminals (with 6-hydroxydopamine plus desmethylimipramine) and the various cell bodies (with ibotenic acid) in the ZI both induced a period of dioestrus (9-11 days). The similarity of effect of these two types of lesion indicate that the DA nerve terminals in the ZI stimulate a stimulatory pathway ultimately to induce LH release.
D000818:Animals; D001111:Arcuate Nucleus of Hypothalamus / Q000502:physiology; D004298:Dopamine / Q000378:metabolism*; D004971:Estrus; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000502:physiology; D006892:Hydroxydopamines; D007031:Hypothalamus / Q000502:physiology*; D007986:Luteinizing Hormone / Q000378:metabolism*; D008473:Median Eminence / Q000502:physiology; D008959:Models, Neurological; D009474:Neurons / Q000502:physiology; D009928:Organ Specificity; D016627:Oxidopamine; D011301:Preoptic Area / Q000502:physiology; D051381:Rats; D011919:Rats, Inbred Strains; D013788:Thalamus / Q000502:physiology*
D006892:Hydroxydopamines; D007987:Gonadotropin-Releasing Hormone; D016627:Oxidopamine; D007986:Luteinizing Hormone; D004298:Dopamine