Summary
The probable role of prolactin (PRL) on the behavioral responses evoked by chronic unpredictable stress (CUS) was studied in adult male rats. Three experiments were performed examining the effect of CUS on behavioral performance in: (i) intact rats with normal endogenous PRL levels, (ii) rats with high endogenous PRL levels, and (iii) rats with low endogenous PRL levels. Behavioral parameters studied were: locomotion, head-dipping, rearing and grooming. Endocrine parameters studied were: PRL and corticosterone (C) plasma concentrations. In Experiment (i) results showed that CUS inhibited significantly locomotion, head-dipping and rearing activity. No variations in PRL plasma levels were found but a significant increase in C was detected. In Experiment (ii) the hyperprolactinaemia induced by pituitary transplants in the kidney capsule blocked partially the inhibition of locomotion due to CUS. No modifications on head-dipping, rearing and grooming were observed. PRL levels in these rats were consistently high as expected and CUS regimen did not change the hormone concentrations in blood. The C response due to CUS, however was completely blocked in the pituitary-implanted group. In Experiment (iii), repeated treatment with bromocriptine (5 mg/kg i.p.) significantly increased the inhibitory effect of CUS on locomotion, head-dipping and rearing. Grooming was also decreased in CUS-treated rats. PRL levels in these animals was low as expected and the C response due to CUS was significantly increased. Results give support to the concept that PRL may have a regulatory role in CUS.
Similar content being viewed by others
References
Alvarez EO, Banzan AM (1985) Further evidence that histamine in hippocampus affects the exploratory behavior in the rat. Physiol Behav 34: 661–664
Alvarez EO, Banzan AM (1986) Histamine and dorsal and ventral hippocampus. II. Effects of H1 and H2 histamine antagonists on exploratory behavior in male rats. Physiol Behav 37: 39–45
Alvarez EO, Banzan AM (1990) Behavioral effects of GABA in the hippocampal formation: functional interaction with histamine. Behav Brain Res 37: 133–143
Bridges RS, Loundes DD, DiBiase R, Tate-Ostroff BA (1985) Prolactin and pituitary involvement in maternal behavior in the rat. In: McLeod RM, Thorner MO, Scapagnini U (eds) Prolactin. Basic and clinical correlates. Liviana Press, Padova, pp 591–599
Drago F, Canonico PL, Bitetti R, Scapagnini U (1980) Systemic and intraventricular prolactin induces excessive grooming. Eur J Pharmacol 65: 457–458
Drago F, Pellegrini-Quarantotti, Scapagnini U, Gessa GL (1981 a) Short-term endogenous hyperprolactinaemia and sexual behavior of male rats. Physiol Behav 26: 277–279
Drago F, Van Ree JM, Bohus B, deWied D (1981 b) Endogenous hyperprolactinaemia enhanced amphetamine- and apomorphine-induced stereotypy. Eur J Pharmacol 72: 249–253
Drago F, Bohus B, Mattheij AM (1982) Endogenous hyperprolactinaemia and avoidance behaviors of the rat. Physiol Behav 28 1–4
Drago F, Amir S, Continella G, Alloro MC, Scapagnini U (1985) Effects of endogenous hyperprolactinaemia on adaptive responses to stress. In: McLeod RM, Thorner MO, Scapagnini U (eds) Prolactin. Basic and clinical correlates. Liviana Press, Padova, pp 609–614
Garcia-Marquez C, Armario A (1987 a) Interaction between chronic stress and clorimipramine treatment in rats. Effects on exploratory activity, behavioral despair, and pituitary-adrenal function. Psychopharmacology 93: 77–81
Garcia-Marquez C, Armario A (1987 b) Chronic stress depresses exploratory activity and behavioral performance in the forced swimming test without altering ACTH response to a novel acute Stressor. Physiol Behav 40: 33–38
Gerendai I, Drago F, Continella G, Scapagnini U (1984) Effects of mastectomy and vagotomy and grooming behavior of the rat: possible involvement of prolactin. Physiol Behav 33: 1–4
Jackson DM, Jenkins OF, Ross SB (1988) The motor effects of bromocriptine — a review. Psychopharmacology 95: 433–446
Katz RJ, Roth KA, Carroll BJ (1981) Acute and chronic stress effects on open-field activity in the rat: implications for a model of depression. Neurosci Biobehav Rev 5: 247–251
Klemcke HG, Nienaber JA, Hahn GL (1987) Stressor-associated alterations in porcine plasma prolactin. Proc Soc Exp Biol Med 186: 333–343
Murphy BEP (1967) Some studies of the protein-binding of steroids and their application of the routine micro and ultramicro measurement of various steroids in body fluids by competitive protein-binding radioassay. Endocr Metab 27: 973–990
Natelson BH, Ottenweller JE, Pitman D, Tapp WN (1988) An assessment of prolactin's value as an index of stress. Life Sci 42: 1597–1602
Rodriguez-Echandia EL, Gonzalez AS, Cabrera R, Fracchia LN (1988) A further analysis of behavioral and endocrine effects of unpredictable chronic stress. Physiol Behav 43: 789–795
Scapagnini U, Drago F, Continella G, Spadaro F, Pennisi GD, Gerendai I (1985) Experimental and clinical effects of prolactin on behavior. In: Mcleod RM, Thorner MO, Scapagnini U (eds) Prolactin. Basic and clinical correlates. Liviana Press, Padova, pp 583–590
Vincent GP, Paré WP, Prenatt JED, Glavin GB (1984) Aggression, body temperature and stress ulcer. Physiol Behav 32: 265–268
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Fracchia, L.N., Jatuff, A.S.G. & Alvarez, E.O. The effect of chronic unpredictable stress on locomotor and exploratory activity in male rats with different endogenous prolactin levels. J. Neural Transmission 89, 179–192 (1992). https://doi.org/10.1007/BF01250670
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF01250670