Biocompatible polymeric microparticles serve as novel and reliable vehicles for exogenous hormone manipulations in passerines

Katharina Mahr, Maria Anzengruber, Anna Hellerschmid, Julia Slezacek, Herbert Hoi, Guruprakash Subbiahdoss, Franz Gabor, Ádám Z Lendvai

Publications: Contribution to journalArticlePeer Reviewed

Abstract

The administration of exogenous hormones emerged as an essential tool for field studies in endocrinology. However, working with wild animals remains challenging, because under field conditions not every available method meets the necessary requirements. Achieving a sustained elevation in hormone levels, while simultaneously minimising handling time and invasiveness of the procedure is a difficult task in field endocrinology. Facing this challenge, we have investigated the suitability of biocompatible polymeric microparticles, a novel method for drug-administration, as a tool to manipulate hormones in small songbirds. We chose the insulin-like growth factor-1 (IGF-1) as target hormone, because it receives great interest from the research community due to its important role in shaping life-history traits. Moreover, its short half-life and hydrophilic properties imply a major challenge in finding a suitable method to achieve a sustained, systemic long-term release. To study the release kinetics, we injected either IGF-1 loaded polylactic-co-glycolic acid (PLGA) microparticles or dispersion medium (control group) in the skin pocket of the interscapular region of captive bearded reedlings (Panurus biarmicus). We collected blood samples for 7 consecutive days plus an additional sampling period after two weeks and complemented these with an in vitro experiment. Our results show that in vitro, PLGA microparticles allowed a stable IGF-1 release for more than 15 days, following a burst release at the beginning of the measurement. In vivo, the initial burst was followed by a drop to still elevated levels in circulating IGF-1 until the effect vanished by 16 days post-treatment. This study is the first to describe the use of PLGA-microparticles as a novel tool for exogenous hormone administration in a small passerine. We suggest that this method is highly suitable to achieve the systemic long-term release of hydrophilic hormones with short half-life and reduces overall handling time, as it requires only one subcutaneous injection.

Original languageEnglish
Article number114234
Pages (from-to)114234
JournalGeneral and Comparative Endocrinology
Volume336
DOIs
Publication statusPublished - 15 May 2023

Austrian Fields of Science 2012

  • 301208 Pharmaceutical technology
  • 106010 Developmental biology

Keywords

  • Animals
  • Polylactic Acid-Polyglycolic Acid Copolymer
  • Polyglycolic Acid
  • Lactic Acid
  • Insulin-Like Growth Factor I
  • Hormones
  • Polylactic-co-glycolic acid (PLGA)
  • Passerines
  • IGF-1
  • Field endocrinology
  • Exogenous hormones
  • Microparticles

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