Nigrostriatal and mesolimbic dopaminergic activities were modified throughout the ovarian cycle of female rats

Abstract

In this work, we have studied the changes in the functional state of nigrostriatal (NSDA) and mesolimbic (MLDA) dopaminergic neurons during the estrous cycle of the female rat. The activity of tyrosine hydroxylase (TH), the turnover rate (Kt) after inhibition of dopamine (DA) synthesis and the ratio between the contents of this amine and its metabolite, L-3,4 dihydroxyphenylacetic acid (DOPAC), were used as indices of neuronal activity. The neuronal activity of NSDA neurons rose during estrous and declined during proestrous, as reflected by the values of Kt and DOPAC/DA ratio measured during both phases. Interestingly, the course of variations in striatal TH activity was similar, although retarded in relation to the changes in neuronal activity. Thus, TH activity was high during diestrous, whereas it was low during estrous. The activity of MLDA neurons was reduced during proestrous. This can be concluded from the decreased Kt and DOPAC/DA ratio measured in this phase and it was accompanied by a low TH activity. Thereupon, both Kt and TH activity increased during estrous. These results indicate the existence of physiological changes in the functional state of both dopaminergic systems during the ovarian cycle, which are partially different for each neuronal pathway. This supports the existence of a specific regulation, and not indiscriminate effects, by the hormones involved in this cycle, mainly estradiol and progesterone.

Parallel processing across neural systems: Implications for a multiple memory system hypothesis

“…Interestingly, estrogenÕs effects may be tied to the effects that estrogen has on the dopaminergic system, at least in striatum. It has been shown that tyrosine hydroxylase and dopamine turnover are higher during rising or high estrogen states compared to during low estrogen states in naturally cycling female rats (Fernandez-Ruiz, Hernandez, de Miguel, & Ramos, 1991). More recent work confirms that estrogen increases dopamine function, especially within the striatum.…”

In the Ventral Tegmental Area, Progestins’ Membrane-Mediated Actions for Lordosis of Hamsters and Rats Involve Protein Kinase A

“…Alternately, progestins may modulate D 1 via more indirect mechanisms; as there is evidence that P can modulate dopamine levels in the VTA. In support, midbrain tyrosine hydroxylase activity, dopamine concentrations, and dopamine turnover are greater in naturally receptive rats, which also have higher progestin levels, than non-receptive controls [5, 45, 46]. Further support that P enhances dopamine includes studies with ovariectomized rats.…”

Toward a rodent model of the Iowa gambling task

“…It has been shown, at least in humans, that the rewarding value of sweet items fluctuates across the menstrual cycle (Cabanac, 1979). Furthermore, it has been shown and argued that the dopaminergic and serotonergic systems are crucial for performing the test (Bechara, Damasio, & Damasio, 2001;van den Bos et al, 2006), both of which show strong fluctuations across the estrus cycle in humans and rodents (Becker, 1999;Dluzen & Ramirez, 1985;Fernández-Ruiz, Hernandez, Demiquel, & Ramos, 1991;Ho, Olsson, Westberg, Melke, & Eriksson, 2001;Justice & de Wit, 1999;Nördstrom, Olsson, & Halldin, 1998;Rubinow, Schmidt, & Roca, 1998;Shimizu & Bray, 1993;Thompson & Moss, 1997). It should be noted that in humans, it has been shown that males and females differ in their performance on the IGT: Males tend to choose on the basis of long-term outcome, whereas females tend to choose on the basis of both immediate wins and long-term outcomes (Overman et al, 2004;Reavis & Overman, 2001).…”