Prolactinomas are prolactin-secreting neoplasias accounting for 40% of the pituitary adenomas. Much is known about the effects of prolactinomas on the reproductive system, but few data are yet available regarding their induced changes on metabolism. This study was aimed at evaluating patients with prolactinomas for insulin resistance and adiponectinemia. Forty patients with prolactinoma were allocated to 2 different groups according to disease control: 20 with uncontrolled disease (UPRL) and 20 with controlled disease in the last 6 months (CPRL). Forty healthy individuals (CG) matched for age, sex, and body mass index were taken as controls. Patients with prolactinoma were compared both as a one group and according to disease control with CG. All subjects were evaluated for waist/hip ratio (WHR), blood pressure, lipid profile, fasting glucose, homeostasis assessment model of insulin resistance (HOMAIR), and adiponectin. Patients with prolactinomas (UPRL+CPRL) showed higher insulin (p<0.05) and HOMAIR (p<0.05), alongside with lower adiponectin levels (p<0.01) than matched controls. When UPRL was compared to CPRL and CG, UPRL was disclosed as a subgroup of significant altered metabolic profile as related to WHR (p<0.01 for comparisons), high-density lipoprotein cholesterol (p<0.05 for comparisons), triglycerides (p<0.05 for comparisons), HOMAIR (p<0.05 and p<0.01, respectively), and adiponectin (p<0.01 for comparisons). All these metabolic abnormalities, except hypoadiponectinemia (p<0.01), were not observed in CPRL. These data suggest that prolactinomas are associated with hypoadiponectinemia, which is further exacerbated in uncontrolled patients when insulin resistance is also prominent.

Pasireotide is a new-generation somatostatin analog that acts through binding to multiple somatostatin receptor subtypes. Studies have shown that pasireotide induces hyperglycemia, reduces glucocorticoid secretion, alters neurotransmission, and potentially affects stress responses typically manifested as hyperglycemia and increased corticosterone secretion. This study specifically aimed to evaluate whether pasireotide treatment modifies glucose and costicosterone secretion in response to acute restraint stress. Male Holtzman rats of 150-200 g were treated with pasireotide (10 µg/kg/day) twice-daily for two weeks or vehicle for the same period. Blood samples were collected at baseline and after 5, 10, 30, and 60 min of restraint stress. The three experimental groups comprised of vehicle + restraint (VEHR), pasireotide + restraint (PASR), and pasireotide + saline (PASNR). Following pasireotide treatment, no significant differences in baseline glucose and corticosterone levels were observed among the three groups. During restraint, hyperglycemia was observed at 10 min (p < .01 for both comparisons), peaked at 30 min (p < .01 for both comparisons) and showed higher 60 min areas under glucose curves in the VEHR and PASR stressed groups when compared to the non-stressed PASNR group (p < .05 for both comparisons). Restraint also increased corticosterone secretion in the VEHR and PASR stressed groups at 5 min (p < .01 for both comparisons), and peaked at 30 min (p < .01 for both comparisons) with corresponding higher 60 min areas under corticosterone curves when compared to the non-stressed PASNR group (p < .01 for both comparisons). In conclusion, pasireotide treatment does not modify hyperglycemic- and corticosterone-restraint stress responses, thus preserving acute stress regulation.