[Functional role of hypothalamic D1 and D2 receptors in organization of some forms of behavior of the common frog].

Dopamine is one of the most ancient, widely spread neurotransmitters that performs a great number of neuromodulator effects in the vertebrate CNS. For the last few years there considerably increases an interest in study of functional role of this neurotransmitter in regulation of various forms of behavior of poikilothermal vertebrates. The present work deals with study of the role of the dopaminergic system, specifically of the hypothalamic dophaminergic system in providing some behavioral frog reactions. We studies behavior of the animals in the "open field" before and after administration to them of antagonists of D1 (SCH 23390) and D2 (haloperidol) receptors as well as of animals with destructed anterior and posterior parts of hypothalamis. Administration of SCH 23390 to intact frogs caused a statistically significant decrease of the number of exploratory reactions and goal-oriented jumps, whereas haloperidol only moderately increased the number of the above reactions. Destruction of the posterior part of hypothalamus inhibited essentially all kinds of activity, while destruction of the anterior part suppressed them completely. Antagonists of D1 and D2 receptors of dopamin little changed the initial motor and emotional activity of the operated animals. The obtained data are discussed in the light of evolutionary origin of D1 and D2 receptors in the vertebrate subphylum and allow concluding that D1 and D2 receptors of hypothalamic dophamin of the common frog are located predominantly in the anterior hypothalamic areas and that their effect on behavior can be mediated and is associated with other brain neurotransmitter systems in such brain structures as lateral hypothalamus, locus coereleus, and striatum that provide different aspects of wakefulness.